tracking down an oil leak

grumpyvette

Administrator
Staff member
step one is to clean the old oil and dirt off the engine with a good degreasing solvent and/or use of a pressure washer so you can positively locate the source of the oil leak,
READ THROUGH THE WHOLE THREAD AND ALL THE SUB LINKED INFO
yes wash the engine, with a good grease solvent spray,
any auto parts store or home depot or grocery store will have a couple gallons of grease solvent and a spray bottle, and Id suggest you buy two gallons of two different grease solvents and soak the engine down carefully before you use the local power car wash if you don,t own a pressure washer.
without the ability to start and run the engine there's no oil flow to track or leak
heads get bathed in oil flung from the pushrods and rockers, there's no oil passages directly feeding oil through chevy heads other than the push rod oil flow to the rockers, and oil drains back through the lifter galleys.
heres an old trick, spray the suspect area with hot soapy water and grease solvent, several times then use a heat gun to dry or just let it sit in the hot sun with the hood open for an hour,you do this to remove all previous oil and grease, then once its totally dry liberally dust the area with TALCUM BABY POWDER ( DO THIS OUTSIDE NOT IN YOUR SHOP) and once done, you start the engine , get a good strong flash light and have a buddy blip the throttle a few times, any oil leak will be very obvious over the fresh talcum baby powder dust on the engine, once you found the leak,obviously repair its source then repeat the soap/solvent wash to remove the talcum powder
most common oil leak sources are valve cover gaskets,bent valve covers,intake gaskets (especially the front and rear china wall seals)
the distributor hold down gasket,leaky oil pan drain bolt gasket, leaking oil filter gaskets, the oil pressure and temp sensors,
if the threads were not coated with sealant, and oil pan gaskets and and valve cover breathers , and rear main seals, timing covers and their gasket and fuel pump mount areas or cover plates, the rear cam tunnel plug is unusual but a possibility


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READ SIMILAR RELATED THREAD'S
http://garage.grumpysperformance.com/index.php?threads/block-prep.125/page-2

http://garage.grumpysperformance.com/index.php?threads/blow-bye-and-breathers.10646/#post-48863

http://garage.grumpysperformance.co...reather-hole-in-valve-covers.2005/#post-35478

http://garage.grumpysperformance.co...vacuum-pumps-do-you-need-one.2207/#post-12639

then you might want to spray suspect areas with a good grease dissolving spray several times in succession, solvents like brake cleaner also work in some areas, remember that, you can,t correct an oil leak with out locating the source,,and a pressure washer, and solvent bath then drying with high pressure air jet nozzle, tends to make finding the source easier sure helps in many applications, but obviously you don,t want to spray ignition or electronics, so be careful....once youve located the oil, or coolant leak, youll need to replace the gasket, freeze plug or leaking hose or broken or worn component thats causing or allowing the coolant or lubricant to leak
a good inspection scope may prove helpful as it allows you to see areas that are very hard to access otherwise
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GOOGLE PV-618 and PV-636

there are bore scopes available that allow a laptop or cell phone to do this cheaply
Just put "cellphone Borescope" into the search function on Amazon. There are a ton of them to chose from. I'm not saying the one I picked was the best. I just read a few and decided on this one. It is from EHome and was 13.99.

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=cellphone Borescope&tag=vs-auto-convert-amazon-20



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IT ALWAYS HELPS TO HAVE GOOD UNDER THE CAR LIGHTING
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http://www.amazon.com/Designers-Edg...306&sr=8-13&keywords=portable+led+work+lights

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http://www.harborfreight.com/portable-halogen-shop-light-66433.html
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watch the video
http://redlinedetection.com/pages/video/

http://garage.grumpysperformance.com/index.php?threads/oil-pan-gaskets.206/#post-1154

theres several potential sources for a leak and several different oil pan gaskets, theres a thick front seal version of the one piece oil pan gasket and a thin front seal, version, mixing the wrong gasket OR mis-matching the oil pan with the BLOCK used ,will generally result in leaks, READ THE LINKS CAREFULLY and take the effort to measure your oil pan, if you select and install the wrong gasket (too thin or too thick for the application IT WILL EVENTUALLY LEAK)

mor-38350_w.jpg

On oil pans I prefer studs, and an oil pan back plate
panback1.jpg
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you might want to Use with P/N 12553058 RH and P/N 12553059 LH oil pan reinforcement plates to distribute the bolt stress on the oil pan rail for 1985 and earlier oil pans P/N 14088501 (LH) and P/N 14088502 (RH).1986 and newer
http://garage.grumpysperformance.co...oving-gaskets-the-wrong-way.10464/#post-43934

http://garage.grumpysperformance.co...l-pan-gasket-still-small-leak.3084/#post-8194
I I like spray brake or carburetor cleaner that removes every trace of old oil, or like several engine wash products,like GUNK ,then follow up with a spray degreaser or most auto supply stores, and large groceries, that sell good DE-greasing solvents in gallon containers , common detergent solvents like 409, Windex or FANTASTIC cleaners help,after the majority of the backed on cruds removed or even hot soapy water with something like dawn dish washing detergent, followed with a pressurized hose several times,
Ive used a light dusting of talcum powder on the suspect areas, on many engines, to make any new oil leaks far easier to locate as the oil flow over the lightly powdered surface is much more easily seen.
especially if the blocks been very recently carefully, cleaned, DE-greased, with solvent spray like brake cleaner that rapidly evaporates, then dried and dusted with TALC, and you have a bright light and a LIFT or the car up on jack stands

I then put the car up on a lift and inspect it with a strong light from both over and under and have a small mechanics mirror available. if you locate the leak you can usually find a way to fix it, but without knowing the source your at a huge disadvantage....
Now naturally the area of the engine will tend to limit the probable suspected sources, but most oil leaks occur around oil pans, timing covers or valve covers
the first step in fixing any oil leak is finding the source, of that leak, theres several suspects on the rear of the block. you'll want to verify whats leaking, potential sources, the rear intake gasket, the oil pressure sensor and the rear main seal are fairly common.
a rear main seal installed facing the wrong direction , the wrong oil pan,gasket, being installed incorrectly, the wrong oil pan, gasket ,the wrong oil filter, the wrong oil filter adapter, or improper installation, or forgetting to connect or loose plug in an oil passage jumps to mind
theres lots of guys that spend days trying to stop leaks the the threads or connection plumbing on those sensors all to no gain, simply because its RARELY the threads that leak, its commonly the sending unit itself that defective and leaking internally,or externally, swap it out and when you install the new version coat the threads lightly with high temp silicone
one old trick is to clean the area with carb cleaner , that tends to leave a dry surface and then dust it with talcum powder , use a strong light and have a buddy spin the oil pump, or run the engine while the cars up on a lift or jack stands , helps, tracks in the talc dust , you applied make it easier to find the source
look at
front/rear intake manifold seal
rear cam freeze plug
oil passage plugs
oil temp sensor
oil pressure sensor
pressure sensor threads
oil pan gasket
rear main seal
oil filter adapter
oil filter
valve covers
timing cover
fuel pump area
distributor base
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this INFO IN RELATED THREADS MAY HELP locate the source[/color]

Be sure the lip seal is positioned leaning inward towards the front of the engine, and the rear seals off-set from the main cap parting line by about 1/4" to reduce the tendency to leak oil

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rear seals come in, rubber, silicon rubber,.Fluoroelastomer, and Viton they all work if properly installed but VITOR usually lasts the longest


http://www.summitracing.com/parts/FEL-BS118291/.. rubber

http://www.summitracing.com/parts/FEL-2909/... Fluoroelastomer,

http://www.summitracing.com/parts/FEL-2900/... Silicone

http://www.summitracing.com/parts/FEL-2918/..viton


viewtopic.php?f=51&t=134

viewtopic.php?f=54&t=3084&p=8194&hilit=rear+seal#p8194

viewtopic.php?f=51&t=2111

http://www.superstreetonline.com/techar ... index.html

viewtopic.php?f=54&t=1396&p=3221&hilit=+switch#p3221

http://forums.hybridz.org/showthread.php?t=126081

I will mention a possibility I have seen several times after an oil changes, sometimes the old oil filter seal will stick to the base of the adapter, on the block, instead of coming off with the old filter. If that happens the new filter can be screwed into place on top of the old, remaining second duplicate seal ring but it will not seal correctly. Usually it will leak as soon as oil pressure is applied to the dual seals, when started, but it is possible it will remain sealed well enough to go a several miles before it fails in rare cases. The filter would be the first thing you check, if you see two seals when you will need to remove the filter and reinstall it or get a new filter depending on the seal condition, ,if your getting oil coming from the distributor area it could be a leaking rear intake manifold seal OR a defective oil pressure sending unit, as these frequently leak oil when they fail, and I'm not referring to a few drips, a constant spray or stream of oil that will allow the pan to go dry in under 15-20 minutes is common when these fail.

Im always surprised at the number of newer guys that don,t realize that one of the forward facing bolt holes intersects the fuel pump push rod guide hole in the chevy block, IF your not using that hole for the old style front motor mount you need to get a 3/4" 3/8NC bolt with THREAD SEALER on the threads installed in that hole or that hole will puke oil constantly at any rpms over idle speeds,but don,t place one in that threaded hole over 3/4" long or it might bind up the fuel pump push rod

viewtopic.php?f=62&t=1430&p=3168#p3168

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the threaded hole might have been plugged with paint, a bolt or sealant that just is no longer there, I have seen several blocks with that hole plugged with a thumb full of silicone thats been painted over, and theres was rather obviously no bolt sealing it, but a 3/4" 3/8"NC bolt with sealant on the threads and a star lock washer is really required if your doing it correctly,on most but NOT ALL BLOCKS that one below the one indicated by the arrow doesn,t go all the way thru but IVE always inserted a bolt with some thread sealant in all the non-used holes just to be a bit more secure
You first have to clean, and degrease the block with a good engine cleaner, spray gunk, and a local car wash with a wand you can use in the engine compartment is a good place to start, when cleaning off and engine to locate the source of oil leaks,youll want to get it completely clean and get it dry. Chalk dust ,or body talc powder or even baking flour in a squeeze plastic bottle like ketchup is occasionally found in restaurants in ,can catch the beginnings of a leak and really help you spot where it is coming from.

IF ALL ELSE FAILS,
theres kits that use UV dye and special light to locate leaks

http://www.amazon.com/Tracerline-TP8621 ... 487&sr=1-2
Typical leak spots are:


Oil pressure sender
rear main seal
front & rear intake rail seal
oil filter seal
rear cam freeze plug
valve cover breather grommet
bent pan or oil pan gasket
front cover seal
valve cover seal
front crank seal
oil filter adapters
oil filter seals
oil coolers and lines
upper pass engine mount bolt hole (shown above)
fuel pump hole.
A fairly complete list but there are other less common ones .

keep in mind theres two distinct sbc gasket thicknesses,
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btw be sure its oil your seeing leak, before blaming the engine and not transmission fluid,or brake fluid, because thats obviously going too be a different source


these sensors are all potential sources for oil leaks but the two blade sensor on the rear of the block, near the distrib base on the early c4 is a known defective part

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http://www.ecklers.com/corvette-oil-pressure-sender-1985-1987.html

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http://www.ecklers.com/corvette-fuel-pump-switch-oil-pressure-sender-1989-1996.html


http://garage.grumpysperformance.co...hetic-oil-cause-leaky-gaskets.2725/#post-7076

Corvette Fuel Pump Switch/Oil Pressure Sender, 1989-1996



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Corvette Oil Pressure Sender, 1985-1987
http://www.ecklers.com/corvette-oil-pressure-sender-1985-1987.html?crosssell=Product_Viewed

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if you find what, you see, or think your sure is, a rear main seal leaking oil and you've replaced it , and it still seems to leak, be aware that the rear oil gallery passage plugs , and rear cam passage plug can also leak, and its entirely possible to confuse the source of a slow oil leak under some conditions, but I'd also point out that high crank case pressure is a big contributor here to oil leaks, so youll want to have adequate venting on the valve covers and ideally a vacuum line too the injection or carburetors plenum, and a crank case vacuum pump certainly will reduce an engines tendency too weep oil. reducing the internal crank case pressure or ideally providing a slightly negative pressure tends to greatly reduce any engines tendency to leak oil past gaskets


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Corvette Oil Temperature Sensor, 1990-1996
http://www.ecklers.com/corvette-oil-temperature-sensor-1990-1996.html
 
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ok next step in locating a leak is to change your oil filter, and verify the oil levels correct,, most Chevy v8 engines will leak, or smoke or run badly if grossly over filled with oil, or run low oil pressure if running significantly lower oil levels than 4 quarts, and make sure you use a quality oil in the 10W30 range as a start point, and use a separate oil pressure test gauge to verify what your true oil pressure is really .
next you'll want to locate the leak, that's usually best done after a trip to a local , drive in u-wash wand ,car wash if its a available, then putting the car on a lift or at least up on sturdy jack stands
oil leaks are much more likely if your engine has a bit of positive crank-case pressure so having an effective PVC and breathers that significantly reduce crank case pressure is a good way to reduce the oil leak potential.
obviously once the leaks located the cause needs to be repaired, if you have low oil pressure indicated once the engine heated up but good oil pressure when cold theres a good chance, some factor in the gauges changes due to heat, and sensors or gauges are suspect, until you prove its not sensors or gauges, a change that radical in oil pressure is rarely a mechanical issue, example if your engine reads 45psi cold but drops to 5 psi once hot but theres no knocking or clicking sounds from the valve train and if your reading 5 psi once the engines hot try dropping in a quart of oil and restarting the hot engine to see if theres a marked change in your indicated oil pressure reading.
viewtopic.php?f=54&t=2725&p=7076#p7076
In my experience, the black rtv works ok,
but the high heat gray or copper gasket sealant has always worked a bit better
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I prefer this for most of the jobs where silicone type gasket sealants get used like intake gaskets and valve cover gaskets

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http://garage.grumpysperformance.com/index.php?threads/sealants-and-threads.805/#post-71928

IVE GENERALLY HAD THE BEST RESULTS WITH ONE PIECE OILPAN GASKETS AND USING STUDS

http://www.summitracing.com/parts/mor-38360
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http://www.summitracing.com/parts/mor-38350
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If you have oil mist or drips of oil exiting the breathers theres potentially several reasons the cause is likely to be a badly designed non baffled breather or a defective PVC valve that's not allowing air flow to be sucked IN thru the breather, , rather than crank case pressure allowing oil mist to exit the breather
(1) the engines rings are not sealing correctly resulting in higher than ideal crank case pressures.

http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/
http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/
http://garage.grumpysperformance.com/index.php?threads/piston-to-bore-clearance.4630/
http://garage.grumpysperformance.com/index.php?threads/installing-rings-in-piston-grooves.9490/


(2) defective PVC valve

http://garage.grumpysperformance.co...lve-cover-breather-hole-in-valve-covers.2005/
http://forum.grumpysperformance.com/viewtopic.php?f=87&t=4636&p=12451#p12451

without proper venting an engines internal pressure builds , due to cylinder pressure leaking past the rings,and eventually will cause oil seals or gaskets to leak oil.
READ THE LINK
http://garage.grumpysperformance.co...stalling-the-intake-manifold-distributor.464/

(3) improper breather design or improper location on the valve cover
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http://www.jegs.com/i/JEGS-Performance-Products/555/52205/10002/-1?parentProductId=763433
mor-38350_w.jpg

On oil pans I prefer studs, and an oil pan back plate
panback1.jpg

fel-0534510t.jpg

you might want to Use with P/N 12553058 RH and P/N 12553059 LH oil pan reinforcement plates to distribute the bolt stress on the oil pan rail for 1985 and earlier oil pans P/N 14088501 (LH) and P/N 14088502 (RH).1986 and newer
always use the manufacturers suggested installation instructions, as some applications or gasket types REQUIRE different lubes or sealants but heres a rough guide, you need to carefully clean and degrease any contact areas where sealants are to be used.
heres a rough guide to help select the correct sealants

yes any component needs to be properly installed, I've seen something similar happen a few times in the past, (persistent slow oil leaks) when guys were using a crank scraper sandwiched between the oil pan gasket and the block,
when guys simply forgot to spray both of the crank scraper surfaces and the block and gasket surface with some sealant like copper coat. hot oil is DESIGNED and formulated to seep into and through small cracks , and if there's no sealant blocking that hot liquid penetrating oil, it will eventually find its way through micro cracks in the area between two metal surfaces, so you,ll want to coat both sides of the gasket and crank scraper with a thin coat of spray sealant just prior to oil pan assembly
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In a properly functioning engine the PVC valve allows engine vacuum to draw fresh outside air into the engine as it operates through the breather,
pressure in the crank case, you see as blow-bye out the breathers on valve covers is the result of cylinder combustion pressure, or to a far lower degree compression, getting past the ring to bore wall seal,the obvious best answer to reducing it is better ring seal.
now doing a ring and bearing refresh/and rebuild is just a weekend deal if your set up with the tools and have a place to work, but of course you may need a re-bore and new pistons, if the bores worn. and if thats true it will take longer and get more expensive due to the labor and machine shop costs and parts required, intermittent blow by is frequently the result of minimal ring damage due to detonation

most installed engines are slightly tilted towards the rear to help oil flow return, to the sump, in the crank case thus the forward 1/3rd of the upper inside roof of the valve covers tends to be a better place to locate breathers and PVC valves to limit oil loss, on most V 8 engines.
 
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" grumpy? I've been chasing oil leaks all over this new engine since it was built. It's a sbc 350, with 10:1 compression and a new set of rings and bearings and a new 7 quart oil pan,and it seems to leak oil from every possible gasket, and its smokes a bit out of the valve covers and the tail pipes?"


Ive seen this frequently on first engine builds and in many cases it boils down to either incorrectly installed gaskets or use of the wrong sealants in each application, or rings that don,t seal well so theres a good deal of crankcase pressure forcing oil past the gaskets, especially if theres no breather and PVC connected which I see occasionally. obviously theres always going to be some pressure getting past the rings so you must have a way to vent the potential pressure build up. doing a leak down test may help


 
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Hey Grump, what about that bottom hole on the block picture there? The one right below the arrowed one. Should that have a bolt in it too?
 
on most but NOT ALL BLOCKS that one doesn,t go all the way thru but IVE always inserted a bolt with sone thread sealant in all the non-used holes just to be a bit more secure
 
XQIZT said:
After any driving, the 77 vette, it gets a small puddle of oil under the dust cover to the flexplatel. The cover doesn't fit juuuussttt right so it appears to me that oil is also flung out of the small gap and onto the exhaust, floor pan, etc on the passenger side. Then it travels backward. So there are small drips coming from all over the passenger side onto the garage floor.

I removed the dust cover to see if I could tell where it was leaking from. I was expecting to see the flywheel covered in oil, but it wasn't. Not even residue. The backside of the crank is also dry. Wouldn't a real main seal leak get the backside of the crank wet, where it bolts to the flexplate? I can tell that the backside of the oil pan is wet, clearly starting at the pan seal.



it sounds like the rear oil pan gasket , that is leaking to me.Id suggest spraying the whole area down with a good spray carburetor, brake or throttle body cleaner to totally degrease the area, put the car on a lift and let it idle while you watch from under the car with a couple strong bright lights for the leaks source.
be aware that the rear of the intake manifold gasket, or a valve cover on the pass side, an oil dip stick or some other source may be your issue so, don,t assume a darn thing, before you actually verify the source of the oil leak,before diving into the project, clean it , degrease it, and locate the source.

but, once you have the oil pan off you may as well also replace the rear main seal.,, IF YOU CARE TO TAKE A TRIP DOWN HERE ILL BE WILLING TO HELP , YOU DO THE GASKET REPLACEMENT AND I HAVE A LIFT, EXPERIENCE AND TOOLS ETC.

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USEFUL RELATED INFO AND YES READING THE LINKS HELPS AS THE PART NUMBERS AND TIPS ARE INCLUEDED
http://forum.grumpysperformance.com/viewtopic.php?f=54&t=206&p=390#p390

http://forum.grumpysperformance.com/viewtopic.php?f=51&t=1718&p=38740&hilit=rear+seal#p38740

http://forum.grumpysperformance.com/viewtopic.php?f=27&t=26
 
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A Rear Camshaft Plug may be leaking oil past.
Or one or both rear Lifter bank oil gallery plugs.
Spraying Baby powder-Talc Powder will help locate the Oil Leak Exact XQ.
Aim & Squeeze the Talc powder full force.
Oil leak will show up definate positive.
Like a stream or river.
Talc baby powder washes off with water easily.
 
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