Removing Valve Seals


Staff member
Assuming new Brodix IK 200 heads. If I remove the valves to work on the head, will I have to replace the seals??? I can't seem to find out what type of seal they use, other than in their info it says "VS529V"

Then assuming I have to replace them, will it be advised or mandatory that I purchase a tool to install them???
many performance valve seals look like these.

If the valve springs are to be removed with the heads still on the car,

the last thing you want is too remove a valve spring and have the valve to drop into the cylinder,
if you use air the crank tends to want to spin the crank to BDC, youll want to verify TDC ,
and make sure the flywheels temporarily prevented from turning from that the TDC position,
Ive used both methods both work,you can put 6 ft of rope in the cylinder while its in BDC then turn it to TDC, Ive used both with zero issues,
If you use the compressor youll want to keep it at 120 psi and constantly feeding pressurized air to keep the valves held in place,
and theres a small chance the compressor pushes enough moisture to allow water to accumulate in the cylinders,
so be sure you spin the engine with the starter with the spark plugs removed several times before you re-install plugs.
if you use the rope, theres a very low chance that the rope will tangle and form a knot that makes removal difficult,
in either case be sure the pistons locked at tdc,
before removing the valve springs, on each cylinder.
theres a good deal of useful info in this article ... index.html

if you need to remove new valve seals its best to replace them as theres some chance they will get damaged in the process, but it is frequently possible to slide a well lubed plastic soda straw over the valve so the keeper notches on the valve stem with there sharp edges are protected from valve seal lips, provided you can find one close to the correct size or you can use heat shrink tubing and lots of assembly lube on the valve stem to protect the valve seal lips, as Ive seen done dozens of times when buying new seals is a PAIN IN THE ASS, due to time or availability or you just want to almost new,re-use little used seals, but with the price of most valve seals its cheaper to just buy new ones.
Ive also seen several guys cut 1' sections of heat shrink tubing to shrink in place over the valve stem notches , oil the tubing after its shrunk, install the valve seals then just pull and discard the tubing, Ive tried that and it works great
Id also point out that youll want to lubricate any valve you install in a valve guide and verify the valve train clearances very carefully, and use the correct valve springs and add the correct valve seals installed ... 19528.html

watch video


The valve-guides for the Vortec heads are the same as all other small-block cylinder heads, but the Vortec heads come equipped with large valve-guide seals.

The valve-guide seals keep oil from running down both the valve stem and valve-guide, and entering the combustion chamber through the intake port at high-engine vacuum and the exhaust port when the engine is not running. This cuts down on engine smoke and exhaust emissions.

This is the valve-spring retainer installed without the valve-spring. The maximum amount of valve lift that the Vortec head will tolerate is the distance between the bottom of the retainer and the top of the valve-guide seal.

you'll want to verify the retainer to valve seal clearance, IS A MINIMUM OF .090 AT FULL LIFT WITH THE CAM YOU'VE INSTALLED, DON,T ASSUME ITS OK, VERIFY IT to prevent valve seal damage,
theres several ways but the easy route is placing a bit of modeling clay shaped like a washer or ring on top of the valve seal,rotating the engine 4 full rotations and then use your calipers to measure the clay thickness after it was compressed by the valve spring retainer.





a second route is to use the correct spring micrometer to measure the valve spring installed height, then measure the clearance with the valve at full lift without the valve springs in place, or with a light checking spring holding the retainer at the two known heights (fully closed and fully open on the valve) as the functional valve springs need not be used if you know the correct measurements, a check spring , and dial indicator on a rigid mount will make that clearance check much easier





The maximum amount of valve lift before the spring retainer hits the valve--guide seal is 0.530 inches. It is generally accepted that 0.060 inches clearance needs to be maintained between the retainer and seal (0.530 - 0.060 = 0.470 maximum valve lift). The Vortec heads, as they come with the large valve-guide seals, are only capable of accepting a camshaft with a maximum valve lift of 0.470 inches.

All small-block cylinder heads built before the '96 Vortec heads had two grooves on the valve stems.

The second groove accepts a quad ring. It sits just below the split lock retainers. The O-ring keeps the oil, which lubricates the rocker arm/valve stem tip, from running down the valve stem and into the valve-guide.

Small Block Vortec Cylinder Heads Specifications - Heads Up!
The O-ring must be accompanied by a tin shield over the outside of the valve-spring (left). The tin shield keeps excess oil from splashing on the valve stem and valve-guide. The tin shield and O-ring must be used together to be effective. Installing the earlier double-groove valves, an O-ring, and a tin shield will allow the Vortec heads to use camshafts with 0.500 inches of valve lift, without machining the valve-guides lower for clearance. View Related Article

iton seals provide better sealing to keep oil out of combustion chambers for improved engine efficiency and performance



Proper lubrication of moving components is vital to engine life, especially in high performance engines. Viton valve stem oil seals have gained quite a reputation for keeping oil in the proper places and out of your engine's combustion chambers. COMP Cams now announces a major expansion of its Viton Metal Body Valve Stem Oil Seal line, providing more versatility and sealing efficiency for engine builders looking for just the right seal, especially where inner valve spring clearance is an issue.

COMP Cams Viton Metal Body Valve Stem Oil Seals are available for 5/16, 11/32 and 3/8-inch diameter valves in a wide range of outside diameters from 0.677-inch through 0.547-inch. This allows the usage of small inside diameter valve springs. They are also available for either 0.500-inch or 0.530-inch OD valve guides. Viton seals, which use a proprietary fluoroelastomer material, are extremely resistant to heat, oil additives and abrasion. These seals are available in kits and include the Mylar installation sleeve. The metal body ensures the seals remain in place and deliver excellent long-term durability. A precision seal installation tool can be purchased from either COMP Cams or Powerhouse.


the upper end of the valve guide needs to be machined to fit the correctly matched valve seal , that sits inside the valve spring, but it helps to have the correct tool for installing them also
555-80596_1.jpg ... tId=962845

things that can cause the guides to go bad are

1) Improper valve train component geometry in the rocker arm sweep on the tip of the valve stem. or improper valve to guide clearances

2) Lack of oil flow to the valve stems and lack of assembly lube on the valve stem before firing the engine.

3) cheap parts that are not clearanced correctly

4) improperly installed valve seals or the wrong valve seals

related threads & links




viewtopic.php?f=52&t=1053&p=1989&hilit=+valve+seals#p1989 ... signs.aspx ... 516501.pdf
Last edited by a moderator:
Valve Stem Seals Materials/Designs

By Larry Carley

Larry Carley

Valve stem seals are something that are always replaced when rebuilding an engine, but do they receive the attention they deserve? Valve stem seals play a critical role in controlling valve lubrication as well as oil consumption. If the seals do not fit properly or are not installed correctly, the guides may be either starved for lubrication or flooded with oil. Either way, the engine is going to have problems - and you're going to have an unhappy customer and perhaps a warranty claim.

Seal longevity is another issue that should be considered when choosing replacement valve stem seals. The material from which the seals are made must be capable of withstanding the harsh operating environment inside the engine for an extended period of time (not just the warranty period). Some materials are longer lived than others, which is usually reflected in the material's price.

High operating temperatures cause lower grade materials such as nitrile to harden and become brittle over time. Eventually, this can lead to cracking, loss of oil control and seal failure. When a valve stem seal loses its ability to control the amount of oil that enters the guide, it can cause a variety of problems.

Spark plug fouling may occur as oil ash builds up on the plug's electrodes. The accumulation of heavy, oily carbon deposits on the backs of the intake valves may cause hesitation and performance problems in some fuel injected engines. As carbon deposits build up in the combustion chamber, compression may increase to the point where it causes engine-damaging detonation and/or preignition problems.

Increased oil consumption due to worn or leaky valve stem seals will also increase hydrocarbon (HC) emissions in the exhaust - which may cause a vehicle to fail an emissions test. Oil burning can also damage the catalytic converter because phosphorus in motor oil contaminates the catalyst. If oil is fouling the spark plugs, misfiring can cause HC emissions to soar as unburned fuel passes into the exhaust. This may damage the converter because unburned fuel in the exhaust makes the converter's operating temperature soar.

The converter may overheat to the point where the substrate breaks down or melts creating a restriction or blockage in the exhaust.

Debris from deteriorating seals is another concern that can cause additional problems inside an engine. Pieces of the seal may clog oil passages starving lifters or rockers for lubrication. Debris may also end up in the crankcase where it may be sucked into the oil pickup screen creating an obstruction that causes a loss of oil pressure - and you know what that means!

A material difference
Depending on the application and the design of the seal, the material used may be nitrile, polyacrylate, fluoroelastomer (Viton), silicone, nylon or Teflon¨. Nitrile is one of the least expensive materials, and has been used for many years in umbrella or deflector type seals for older pushrod engines. Nitrile's temperature range is -40º to 250º F. It can withstand intermittent operating temperatures of up to 300º F, which is usually good enough for intake valve seals but not exhaust valve seals.

A step up from nitrile is polyacrylate. Polyacrylate is about twice the cost of nitrile and has a temperature range of -30º to 350º F; it is a good step up from nitrile for umbrella seals.

It is also used for some positive seals as well.Some engines such as older big block Chevy V8s have positive seals made of nylon. Nylon is a hard material with a temperature rating of -40º to 300º F. Nylon is impervious to oil, but it can melt if the engine overheats.

A higher grade seal material is silicone, which is rated from -60º to over 400º F, depending on the grade of the material. Some silicone seals can operate at 330º F continuously and handle up to 400º F intermittently, while others can take 375º and go as high as 450º to 500º F intermittently without damage. Silicone is a good high-temperature material, but costs four to five times as much as nitrile.

In the mid-1980s, positive valve stem seals made of fluoroelastomer materials (FKM and Viton) began to appear in import and domestic overhead cam engines. Fluoroelastomer seals cost roughly 12 times as much as nitrile, but have a temperature range of -5º to 450º F, making them one of the best high-temperature seals available.

Viton has good flexibility like nitrile, which means it can handle some runout between the valve stem and guide. It is also considered to be a more durable material than silicone. Viton also has better wear resistance than most other seal materials, making it a good choice for applications where long term durability is a must.

The highest rated positive seal material is Teflon, with a range of -5º to 600º F. Like nylon, Teflon is a hard material so it cannot handle as much runout between the stem and guide as more flexible seal materials can. What's more, Teflon is expensive - costing 20 to 25 times as much as nitrile.

Material identification
It's important to know what type of material the valve stem seals are made of when rebuilding an engine so you can replace same with same, or better. Upgrading to a better grade of material should certainly be considered if the original seals are badly deteriorated and you have a choice as to the type of seal material that's available for the engine. Upgrading from nitrile to polyacrylate, silicone or Viton, for example, would provide better durability and longevity if the original nitrile seals were found to be hardened or falling apart.

Identifying seal material
How can you tell one type of seal material from another? Color is not necessarily an accurate guide because the same material may come in several different colors. Nitrile seals may be black, green or blue. Polyacrylate is usually black, while Viton may be brown, orange or black. Nylon has a translucent appearance while Teflon is white. Silicone is usually black.

Replacement seals may not be the same color as the OEM seals even if the materials are identical, while others may be the same color but made of a different material. The color identification information contained in some OEM service manuals is also inaccurate. So going by color alone is not a very good way to tell what type of material is in a valve stem seal.

Some engines may also have two different types of seal materials which may be color coded to distinguish the intake and exhaust valve guide seals (a higher temperature material being used for the exhaust valves). AERA has published a technical bulletin (September 1997, TB 1488) identifying the seals used in 1984 to '96 Chrysler/Jeep 2.5L and 4.0L engines. On this application, black seals (polyacrylate) are used on the intake valves and brown seals (Viton) are used on the exhaust valves.One way to identify an unknown seal material is with a burn test:

Nitrile will burn easily and produce thick black smoke that smells like burning rubber.
Polyacrylate will also burn easily producing a less dense black smoke that smells like burning plastic.
Silicone will turn white when burned, regardless of the original color of the seal, producing smoke that has little color and no odor.
Viton/fluoroelastomer seals will be difficult to burn and produce white smoke with no odor. The seal color will either remain the same or turn black.

Choosing the "right" seal
Most aftermarket suppliers of valve stem seals use the same type of seal material as that used by the original equipment engine manufacturer. That's because many aftermarket suppliers source their seals directly from the OEM supplier rather than make the seals themselves. Others who do manufacture some of their own seals may use the same or a higher grade of material in their seals.

Some suppliers substitute silicone or Viton for nitrile to provide better, higher temperature performance for extended durability. But there are also aftermarket suppliers who cater to those who are looking for the least expensive seals they can buy. Such suppliers typically use the least expensive grade of seal material (nitrile) to reduce cost.

The "right" seal material for any given engine application will depend on the design of the engine and OEM seal, the "normal" engine operating temperature, how the engine will be used (normal service or heavy-duty use), whether or not the OEM seals performed adequately in the new engine application, and how important seal longevity is to you and your customer.

A lower grade seal material such as nitrile may be okay in a low-priced rebuilt engine for normal everyday driving, but may not be adequate in a more demanding application. Chuck Wible of Anderson Automotive, Louisville, TX, is an example of a rebuilder who says he usually likes to go up a step when replacing seals in his rebuilt engines. "If the original seals are nitrile, I usually replace them with polyacrylate or silicone. I prefer silicone for umbrella seals and Viton for positive seals," he said.

Seal design
Valve stem oil seals come in two basic types - umbrella seals and positive seals. Used mostly on older pushrod engines, umbrella or deflector style seals (which also include O-rings) are installed on the valve stem and ride the stem up and down as the valve opens and closes.

An umbrella seal controls the amount of lubrication the valve guide receives by deflecting oil splash away from the guide. An O-ring does the same thing by preventing oil from flowing down the valve stem into the guide. Umbrella seals are a simple and effective design, and are easy to install. But they do not provide the same degree of oil control as positive seals.

Positive seals are used on most late model engines for two reasons: emissions control and oil control. A positive valve stem seal provides a tighter seal which reduces the amount of oil that enters the guides. This minimizes oil consumption and hydrocarbon emissions, and also helps to keep intake vacuum high for better idle quality (air being sucked past worn valve guides and seals can cause lean misfire and a rough idle).

A positive seal is also needed in most overhead cam engines to prevent oil from flooding the guides. An umbrella seal cannot handle the amount of oil that's found in most OHC heads.

Unlike an umbrella seal, a positive seal does not move. It is pressed in place on the end of the valve guide and wipes the oil off the valve stem as the stem moves up and down. The seal does not actually make direct contact with the stem but rides on a thin film of oil creating a hydrodynamic seal. This allows a small amount of oil to slip past the seal to lubricate the guide. For this reason, a precise fit is extremely important with a positive seal to get accurate oil metering.

If a positive seal fits too loose around the valve stem, too much oil will get past the seal and flood the guide. Oil consumption will go up along with all the problems that go with too much oil in the combustion chamber. If a positive seal fits the stem too tight, the hydrodynamic seal may be lost as the oil film is scraped off the stem. This will starve the guide for lubrication causing increased valve stem and guide wear (seal wear, too), and may even cause the valve stem to overheat, gall and stick.

Subtle differences in the design of the sealing lip and the wire or spring around the neck area of the seal play a big role in the seal's ability to do its job. The wire or spring in the neck area helps support the seal so it can conform to the valve stem. Design differences here and in the design of the lip determine how much deviation in valve stem diameter the seal can handle.

Most positive seals can't tolerate more than .005ý difference in the valve stem diameter from the stock size. If you're installing new valves with oversized stems, therefore, replacement seals with a larger inside diameter (I.D.) would be required. Likewise, if you're reusing valves and grinding the stems, replacement seals with a smaller I.D. would be needed.

Even so, some aftermarket positive seals are designed to handle valve stems from .005ý undersize to .015ý oversize. So before choosing a seal, check with the seal supplier to find out the range in valve stem sizes it can accommodate.

Lip abrasion of a positive seal can occur if oversized valves are used with standard sized seals. Lip damage can also occur if the valve stems have been reground and the finish of the stems is too rough. But one of the most common causes of lip damage is not lubricating the seals and stems when the engine is assembled.

Some type of lubrication must always be used with positive seals (motor oil or assembly lube). The seal I.D. must also be protected during installation by using a sleeve over the end of the valve. The sharp edges around the keeper grooves may cut or tear a positive seal, so that's why some type of protection is required during assembly.

Another thing that needs to be considered with positive seals is concentricity. The metal jacketed-type of positive valve stem seals found on many Japanese engines and late model domestic OHC engines provide good support and help hold the seal perpendicular to the valve stem. However, they are more rigid than the nonjacketed-type of positive seals (the same is true for Teflon positive seals).

Consequently, the outside diameter (O.D.) of the guide chimney needs to be concentric with the inside diameter of the guide for a good seal. On most applications, there should be no more than about .010ý of runout. Too much runout can deform the seal lip preventing it from sealing properly resulting in increased oil consumption and uneven seal wear.

On small block Chevy and Ford V8 engines where positive seals are used on cast iron guides, lack of concentricity is often a cause of oil consumption and premature seal failure. Some engines may be off as much as .030ý from the factory! The same kind of problems have been seen in Ford 6.9L and 7.3L engines. Concentricity problems can usually be avoided by centering off the valve guide I.D. when machining the guide chimney O.D.

Some newer engines such as GM's 3.1L and 4.3L V6 and Ford's 4.6L V8 use a positive seal design that has an integral spring seat. This keeps the valve spring from galling the aluminum head and also helps center the seal on the valve stem. On heavy-duty diesels this design is often used to keep the seals from blowing off the guides when the engine is under boost pressure.

Replace same with same?
Most seal suppliers say rebuilders should stick with the same design of seal that was originally used in an engine. In other words, replace umbrella style seals with umbrella seals, and replace positive seals with positive seals.

Older pushrod engines usually have O-rings or umbrella style valve stem seals because that was the type of seal design that was in general use at the time the engine was originally designed and built. So, in most instances, replacing same with same should provide the same degree of oil control and lubrication.

Positive seals, on the other hand, are used on most late model engines and OHC engines to minimize oil consumption and emissions. Positive seals are also required on most OHC engines because umbrella seals can't handle the volume of oil found in most OHC heads.

Some rebuilders, though, don't always replace same with same. The reasons vary depending on the application. On some engines, a rebuilder may replace the original umbrella style seals with positive seals to get better oil control. Some rebuilders are also replacing positive seals in certain pushrod engines with umbrella style seals to save money and make installation easier.

Chuck Wible of Anderson Automotive says he's had great success converting newer small block Chevy and Fords as well as 173 Chevys from positive seals to umbrella seals. "It saves half the cost, and makes it easier and quicker to install the seals," said Wible. "But it only works on some engines. You have to look at the angle of the head. If there's no risk of flooding the guide area with oil, you can probably change to an umbrella style seal. Otherwise, you should stick with a positive type of seal. The Chevy 151, for example, has a flat head that puddles oil so it would not be a good choice for an umbrella seal."

Heat is an engine's worst enemy. Heat can damage valve seals as well as many other engine parts, so it's not surprising that overheating is a common cause of engine failures and warranty claims.

The most common cause of overheating is loss of coolant, often due to a failed radiator or heater hose and/or a leaky radiator. An engine can also overheat if the thermostat sticks shut (a good reason for using a "fail-safe" type of thermostat). But overheating can also occur if the cooling system is not filled properly after installing a rebuilt engine or when changing the coolant (air pockets in the block).

An engine can also run hot if there's a blockage in the radiator, the cooling fan or fan clutch fails, there's a blockage in the exhaust system, ignition timing is incorrect or the fuel mixture is off. Regardless of what caused the engine to overheat, it's often hard to prove that overheating resulted in engine damage.

The telltale symptoms of severe overheating may include piston seizure and scuffing, galled valve stems, damaged valve guides, and/or a warped or cracked cylinder head. But these conditions may also be blamed on other factors such as incorrect assembly tolerances or a lack of lubrication.

Your first line of defense in such instances is proof that the engine did indeed overheat (regardless of the cause). A heat tab can provide such proof by indicating a certain temperature was exceeded in operation.

A typical heat tab for a gasoline engine has a center plug that melts out at 250º to 255º F. If the engine has gotten hot enough to melt the heat tab, any damage it suffered is likely not the rebuilder's fault. Lower temperature heat tabs are also available for other applications such as marine (187º to 192º F) and diesel (225º to 230º F).

Heat tabs, when used properly, provide an acceptable defense against unjust warranty claims. The validity of heat tabs as a reliable and proven means for monitoring engine temperature has also held up successfully in court cases involving engine warranty claims.

Heat tabs can be mounted almost anywhere on the engine block or cylinder head. Many rebuilders will install one heat tab on the block and one on each cylinder head in a V6 or V8 engine.

The heat tab should be positioned where it will give a good indication of average head temperature, but away from exhaust ports, manifolds or pipes. The heat tab should also be located in a protected position so it isn't accidentally damaged or knocked off during engine installation or normal use. For engine blocks, a good location is in the recess of a freeze plug. For heads, almost any exterior surface not adjacent to the exhaust ports will work.

Traditional heat tabs are small round metal buttons that are attached to the engine with high-temperature, high-strength adhesive. For a secure attachment, the mounting surface on the engine must be clean (no oil, dirt or grease).

Heat indicating labels available through Engine Rebuilders Association (AERA) can also be used to monitor temperature readings. The self-adhesive labels have a series of windows from 180º to 280º F that turn black when the indicated temperature is reached.

One very important point to keep in mind when using heat tabs or labels for warranty protection is to make sure your customer understands why the tab or label is on the engine. They should know that the engine warranty is void if the tab indicates overheating has occurred or if the tab is removed.

For added protection, some rebuilders have been known to hide an additional heat tab in a less obvious location just in case the most visible heat tab has been removed or tampered with.

Using a "personalized" heat tab with your company's name or logo on it is also a good way to identify parts you've rebuilt, and to assure the heat tab on the engine is the same one you installed.

Heat tabs are relatively inexpensive. Metallic heat tabs generally cost less than about 35 cents each, and heat-sensitive labels can be bought for less than 95 cents each. Considering the potential expense of a warranty claim, heat tabs are very cheap insurance.
Valve Guide Reconditioning ... oning.aspx

By Larry Carley

Larry Carley

The condition of the valve guides in an engine is extremely important because they support the valve stems and cool the valves. But worn guides increase oil consumption, and too much clearance between the guides and stems can make the valves run hot, increasing the risk of burning an exhaust valve. A valve loses about 15 to 30 percent of its heat through the stem. On the exhaust side where there is no cooling effect from the incoming air/fuel mixture, the guides are critical, because cooling through the stem is especially important for valve longevity.

Worn intake guides or ones with too much clearance can also allow "unmetered" air to be drawn into the intake ports. The effect is similar to that of worn throttle shafts or a vacuum leak in the intake manifold: the extra air reduces intake vacuum and upsets the air/fuel calibration of the engine at idle, which may contribute to a lean misfire condition or a rough idle.

There’s also the problem of loose guides. Some cylinder heads such as those on Chrysler/Mitsubishi 3.0L V6 engines are notorious for loose guides. In such cases, it may be necessary to install oversized replacement guides to fix the head.

Simply put, valve guides can have a big impact upon an engine’s performance.

How you choose to recondition the guides will vary depending on what kind of engine rebuilding operation you have. Large production engine rebuilders typically have a set procedure for reconditioning all the guides based on which method costs the least and yields the best results for them. They may ream out the old guides and install new valves with oversized stems or rechromed stems, or they may ream out the old guides and install bronze guide liners to restore the original clearances. Performance engine builders often prefer bronze guide liners to improve lubricity and resistance to seizure. Custom engine builders may use either method depending on customer preferences and how much a customer wants to spend.

On aluminum heads with replaceable guides as well as cast iron heads with non-integral guides, worn guides can be reconditioned by driving out the old guides and replacing them with new ones, reaming the original guides to oversize to accept valves with oversized or rechromed stems, or reaming out the worn guides and installing guide liners. Most shops that work on aluminum heads usually replace the guides if they are worn. Hard powder metal guides can be difficult to ream so that’s why they often replace rather than recondition the guides. But new solid carbide reamers are available that have a six-flute design and can cut powder metal guides as easily as cast iron guides.

On cast iron heads with integral guides, the most popular methods of reconditioning guides is to ream out the guides to accept valves with oversized or rechromed stems, or to ream out the guides and install guide liners. In cases where the original integral guide is too badly worn or damaged to accept an oversize valve or a guide liner, some heads may be salvaged by installing a whole new guide.

When used valves are salvaged and the stems are reground, grinding removes the chrome flashing. Chrome prevents the stem from galling when cast iron guides are used, and it helps prevent positive valve seal wear on intake valves. If the chrome is ground off and the valve stem is not replated, it must be used with either a bronze liner or guide.

Knurling is another technique that can be used to restore guide clearances, but only if guide wear is limited (.006˝ or less). Most engine builders today see knurling as a “temporary” fix that only provides limited benefits and won’t last over time. When the knurling tool is run through a guide, it leaves behind a spiral groove that acts like a furrow to raise the metal on either side. This reduces the inside diameter of the guide so a reamer can then be used to resize the guide back to (or close to) its original dimensions. The grooves also help retain oil for improved lubricity, which means you can tighten up clearances a bit compared to stock. But the bearing surface area created by knurling is not as great as a smooth surface, so over time it will wear more quickly.

So how do you decide which method is the best one for you? There’s no easy answer to that question because the answer depends on the type of head that’s being reconditioned, your labor costs, how competitive you have to be with your pricing, how much your parts cost, what percentage of valves you can salvage, whether you buy rechromed valves or rechrome used valves yourself, and most importantly what your customers want.

The bottom line is that you want to use a guide reconditioning method that is reliable, affordable, profitable and doesn’t cause problems down the road.

New Valve Guides
If you opt to replace the original guides, the old guides are easiest to remove when the head is warm. This can be done just after the heads have come out of a cleaning oven or spray washer. The removal procedure will vary depending on the head, but most can be driven out pneumatically.

Chilling the replacement guides can reduce the amount of interference during installation. Using a lubricant can also reduce the risk of galling. With tapered guides, care must be taken to install them from the right side. Most wet guides are tapered, and also require sealer to prevent leaks.

If the old guides are loose, the holes will have to be machined to oversize to accept new guides with oversized outside diameters. The amount of interference fit should be the same as before, or slightly higher if the head has a reputation for loose guides.

Replacing the guides may change the concentricity of the valve slightly with respect to the seat, but this should be restored when the seats are recut using a centering pilot in the guide.

As for the type of guide to install, many shops use the same type as the original and replace same with same (bronze with bronze, cast iron with cast iron, or powder metal with powder metal). Powder metal guides may be more expensive, so for some applications it may be more economical to substitute cast iron or bronze guides for the OEM powder metal guides. But these other materials may not provide the same longevity as powder metal.

Guide Liners
Liners have long been used to repair worn integral guides in cast iron heads, but can also be used to restore worn cast iron guides in aluminum heads. The main advantage with this approach is that valves and guides don’t have to be replaced. This assumes the original guides in an aluminum or cast iron head with non-integral guides are still tight and that the original valve stems are not worn excessively (worn valves can be reground to fit liners with undersize IDs). The cost savings can be significant depending on the application, and it eliminates the labor and risks of driving out the old guides and installing new ones. Powder metal guides tend to be brittle and can be difficult to replace.

Bronze liners provide good lubricity and reduce the risk of galling and seizure. On the other hand, installing liners requires a couple of extra steps, which must be done properly to assure proper clearances and fit.

If you opt for liners, there are several from which to choose: thin wall phosphor bronze in various configurations (split and solid designs), and cast iron.

The key to using a split type of bronze liner is proper installation. The original guides should not be worn more than .030˝ or cracked, otherwise replacement is recommended. The first step is to bore out the guides to accept the liners. Use a carbide reamer in an air drill with a no load speed of 2,100 to 3,000 rpm. Special fixtures are available with centering pilots that center the reamer off the valve seat rather than the guide hole to maintain seat concentricity. Guides should be bored dry with no lubricant, using steady consistent pressure.

Once the guides have been bored out, they should be blown out and checked with a go-no go gauge to make sure they’re the proper size. Next, the liners are pressed in – usually from the top of the head using an air hammer and installation tool. But on some aluminum heads with powder metal guides, better results can be achieved by installing the liners from the combustion chamber side. Liners go in with the tapered side facing the guide hole. The liners are then driven in flush with the top of the guide.

Sizing the inside diameter of the liner is the next step. Any of three different techniques may be used: roller burnishing (use with lubrication), broaching (driving a calibrated ball through the liner with an air hammer), or using a ball broach tool in an air hammer. This is the most important step because it provides the proper clearances between valve stem and liner for good lubrication and oil control, and it locks the liner in place so it will transfer heat efficiently to the head.

Once the liners have been sized, the head can be turned over so the liners can be trimmed to the proper length unless precut liners are used. Liners are usually cut flush with the guide boss in the port.

The final step is to flex hone the liner. Honing removes any burrs left from trimming the liner to length, and leaves a nice crosshatch finish that improves oil retention. One pass in and out is all that’s recommended to hone the liner. A flexible nylon brush should then be passed through the liner to clean the hole.

With some one-piece bronze liners, broaching after installation is not necessary. The liners have an interference press fit of about .001˝ to .0015˝, which requires boring the guide to exact dimensions. Broaching is required for cast iron liners, though, to seat the liner in the guide.

Oversize Valve Stems
Valves with oversized stems are typically available in a range of sizes including .003˝, .005˝, .008˝ and .015˝, with the .015˝ being the most popular because it can accommodate greater wear in the guides.

Installing new or rechromed valves with oversized stems is essentially a two step operation as far as guide reconditioning is concerned. Step one is to ream the guides to oversize. Step two is to finish the holes with some type of honing tool. A reamer fractures metal and leaves microscopic pullouts, tears and a relatively rough guide surface. Even new guides can be rough inside. Honing removes this debris from the surface, improves oil retention and allows somewhat closer stem to guide clearances for better oil control and heat transfer.

One supplier of rechromed valves said, "One of the biggest changes in this industry today is that rebuilders are realizing their niche isn’t salvaging small parts like valves, it’s building engines and salvaging the large high dollar parts. Rechromed valves can be very price competitive with new valves, and save rebuilders the cost and hassle of reconditioning their own valves."

Fred Calouette of Cal Valves, Escanaba, MI says his oversized valves not only eliminate the need for guide liners or replacement guides, but they also solve a lot of problems for rebuilders who use salvaged valves.

"In addition to cleaning, inspecting, hard chroming and precision grinding valves to standard or oversize dimensions, we can also test valves for cracks and hardness. We can do custom valves on a limited or production basis, and can shorten valves if a rebuilder needs a shorter valve to compensate for valve seat refinishing or push rod adjustment."

"If a rebuilder is involved with an OEM engine program and has to use OEM valves, we can give him back reconditioned OEM valves so he doesn’t have to buy new valves. We have over 300 part numbers for both heavy-duty diesel trucks and passenger cars."

Calouette said that in spite of a lackluster year for aftermarket engine builders, his business is up 10 percent this year and will probably finish 12 to 15 percent higher by year’s end.

Guide clearance can be checked after cleaning the valve stem and guide with solvent and a brush to remove all gum and varnish. Insert the valve into its guide, then hold it at its normal opening height while checking side play with a dial indicator. If play exceeds the specified limits, measure the valve stem with a micrometer to see if it is worn excessively (more than .001˝ of wear calls for replacement).

A fast way to check guide wear is with a gauge set designed for this purpose. A gauge set will give you precise measurements and can be used to measure any portion of the guide.

To measure guide wear (as well as taper) using a telescoping or split ball gauge, measure the guide ID at both ends and in the middle. Subtract the middle reading from the ends to determine taper wear. Compare the smallest ID measurement (usually in the middle of the guide) to the factory specs to determine total wear.

Do not use a valve seat grinding pilot to check guides. A valve guide pilot will fit snugly in the unworn center section of the guide but not give a true indication of the amount of bellmouth wear at the ends of the guide.

Valve stems should also be measured to check for sizing as well as wear. Nominal sizes vary quite a bit depending on the application, and there’s no way of knowing if a valve has been replaced previously with one of a different size unless the stem is measured. Many late model engines have tapered valve stems. Taper stem valves are ground with the stem diameter smaller at the head end of the valve. This is done to create a larger clearance at the head where the temperatures are highest. This reduces the change of galling with unleaded fuel and narrow three-angle valve seats. When measuring a tapered stem, check the outside diameter about an inch in for each end.

Different engines have different clearance requirements, so always refer to the factory specifications. Stem-to-guide clearances normally range from .001˝ to .003˝, and .002˝ to .004˝ for exhaust guides. The exhaust guides usually require .0005˝ to .001˝ more clearance than the intakes for thermal expansion.

Diesel engines as a rule have looser specs on both intake and exhaust guides than gasoline engines, and heads with sodium-filled exhaust valves usually require an extra .001˝ of clearance to handle the additional heat conducted up through the valve stems.

The type of guide also influences the amount of clearance needed. Bronze guides, as a rule, can handle about half the normal minimum factory clearance specified for cast iron guides or integral guides because of the anti-seize characteristics of the material and its superior oil retention qualities. A knurled guide, one with oil retention grooves or a bronze threaded liner all provide better lubrication than a smooth guide. Consequently, clearances for these types of guides can also be tighter. Half the factory minimum specified clearance is sometimes acceptable.

The type of valve seal used also has a bearing on clearances. Positive valve seals, which are used on most engines today, reduce the amount of oil that reaches the valve stem compared to deflector or umbrella type valve seals. A guide with a deflector valve seal in an older engine application may need somewhat tighter clearances than one with a positive valve seal to control oil consumption.

Unusual Guide Wear
All guides will show some wear at high mileage, but excessive wear or unusual wear may indicate other problems that need to be addressed. Severe guide wear may be due to inadequate lubrication, improper valve geometry or wrong valve stem-to guide clearance (too much or too little).

Inadequate lubrication may be caused by oil starvation in the upper valve train due to low oil pressure, obstructed oil passages, push rods, etc. Lack of oil can cause stem scuffing, rapid stem and guide wear, possible valve sticking and ultimately valve failure due to poor seating and overheating.

Geometry problems include the wrong installed valve height, and off-square springs, rocker arm tappet screws or rocker arms that push the valve sideways every time it opens. This causes uneven guide wear, leaving an egg-shaped hole. The wear leads to increased stem-to-guide clearance, poor valve seating and premature valve failure.

Installing new guide liners is a five-step process.

Bore: Using a carbide boring tool with a high RPM air drill, bore out the original guide.

Install: Blow away chips and lube the guide hole with appropriate lubricant. Install valve guide liner into holder assembly of installation tool. Drive guide liner into place using short-stroke heavy-duty air hammer.

Size: Finish the procedure using one of the following methods:

Ball Broach: Insert the ball broach into guide and drive by air with a broach holder and air hammer.

Roller Burnish: Use with a heavy-duty air drill. Insert burnisher into guide and allow self-feeding action to finish the process.

Carbide Ball: Rest ball on top of guide liner and drive using a pneumatic ball driver and air hammer.

Trim: Insert appropriate size pilot into carbide guide cutter. Use a 950 rpm air drill to remove any excess liner material from each side of the valve guide.

Flex Hone: Run the appropriate sized Flex-Hone through the new guide liner using a 2,100 rpm drill. One pass up and one pass down will provide the desired finish.

The valve spring compressor should be available for free (deposit required) at your favorite auto parts store. The air pressure trick isn't the only alternative, and sounds a bit awkward, especially at cyl #8. I'd like to hear from someone who's actually done it, rather than theory.

Another way that sounds reliable (but I haven't tried it myself . . . see para. 1!) is to remove all spark plugs and rocker arms, then rotate the engine so the piston of the cyl. being worked on is down. Push about a foot of soft rope, about 3/16 dia., into the cylinder, then rotate the engine until the rope is pushing against the valves. After the seals and valve springs are replaced, back the engine off the rope and pull it out.

The spring compressor I borrowed worked better with a hose clamp around it to keep the spring from popping out.

The intake and exhaust seals are different, because the intake can see a high vacuum, but the exhaust doesn't, but oil can seep into the exhaust. You can see why the exhaust seals are called "umbrella" seals.

There are also seals inside the valve spring retainers, that fit into the bottom groove of the valve keeper area.

Use a magnetic tool to hang onto the little keepers, since you'll have the spring compressor in the picture, unlike the above photo! Keep track of which spring goes where. The exhaust springs have "valve rotators" in our engines.
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Grumpy, Do You have a Sealed Power Valve Guide parts & dimension spec listing ?
I lost the one I had.

Cast Iron guides smooth.
Steel Guides smooth.
Bronze Smooth.
Bronze Stepped O.D. Pre machined for P.C. style positive valvesten seals.
.500" & .530".

I have done valve guide replacement prior. ... lve-Guides ... ditioning/

its generally a very good idea to keep all the cam, lifter,valve train and cylinder head components in matched sets, keep components in labeled matched sets, if you intend to reuse used parts in a rebuild. as each wears in, or laps in to its matched components a bit differently thus random assembly increases the chances of future parts

btw, if the parts will be sitting on a shelf in the work shop while you wait, a good soak with wd 40, and wrapping a few criss crossed layers of saran wrap plastic over the loose parts is a good idea as it prevents moisture damage and tends to keep the parts in the correct location slots, and if your working on more than one engine type out some detailed info as to the build ID and place it under the saran wrap.





to reading links!
but for those guys who care to learn more these links might be useful
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exhaust valves operate at considerably higher heat levels,
they are frequently made of different materials and color coded,
so you won,t mix up the location installed,
obviously that requires you to know the difference and ask questions

Intake valves operate under a vacuum so the guides can pull oil down the stem,
exhaust valves are not exposed to this, and operate at higher heat
,so sealing oil flow from valve guides is less critical or beneficial

related info

so you'll potentially cause damage if you use the more restrictive intake valve seals on the exhaust valves
There are two basic valve stem seal designs: but dozens of manufacturers
Deflector seals – also called umbrella seals, deflect oil away from the valve stem.
They are secured to the valve stem and move with the valve to shield the valve guide from excess oil.
Umbrella type seals were commonly used prior to the development of positive type seals.
Positive seals – attach to the valve guide boss and function as squeegees, wiping and metering oil on the stem as they pass through the seals.



valve seals frequently differ in design , diameter, height, inside and outside diam, and color
so be sure whatever seal you select is designed to match the intended location and application, when installing,
know what you bought,and where it goes
be sure it matches your intended application,
and be sure to ask, lots of questions and measure accurately
and yes that means both the heads and valve seals..

measure clearances on the valve guides and inside the valve springs ,
and under the valve spring retainer to valve guide accurately:rolleyes:

related links

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from what I heard,
the valve spring sleeves on the springs you occasionally see,
are designed to help reduce or meter oil entering the valve guides and seals,
so installed as a team/set the seals last longer


valve spring sleeves are much more commonly used on overhead valve engine combos

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the valve spring sleeves on the springs you occasionally see,
are designed to help reduce or meter oil entering the valve guides and seals,
so installed as a team/set the seals last longer

Valve seals today are designed to meter the oil flow into the guide.

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