Hi pressure in cooling system

Discussion in 'Tools, Procedures, and Testing trouble shooting' started by Tom, Mar 26, 2016.

  1. Tom

    Tom 69 vette big block

    I built a 496 BBC blower motor, gen iv merlin block and edelbrock rpm 60559 heads and at first start up, only ran 5 minutes and I blew out the heater core.
    I cant find the problem, I took off the intake and gaskets look real good. compression test was all good at 150psi. oil looks milky grey white.
    my bore is 4.310 and I used a felpro 1027 headgasket, I was told I should have used a 10171 and my problem would not have happened.
  2. 87vette81big

    87vette81big Guest

    Oh man...
    Headgasket sealing issues.
    Dump the Engine crankcase oil as soon as possible .
    Antifreeze and engine oil mix is Very bad on engine bearings.
    Don't start and run the engine no more till you solve the issue.
    Grumpy does all the Big Block Chevy Tech here although I have worked on BBC Engines stock to Full Drag Race.
    And I have worked on BBC Full Race Marine Engines in Fountain Cigarette Boats.

    We used a special Fel Pro MARINE BBC Headgaskets in the past for Severe Drag Race use in Franks old 1969 SS/RS Camaro. 500-800 HP Nitrous shots on top of 800-850 HP Normal aspirated RACE BIG BLOCK CHEVY.
    Never lost a Headgasket again using MARINE BBC Fel Pro Headgaskets.

    Grumpy likes Copper Headgaskets.
    He will be around soon.
  3. Tom

    Tom 69 vette big block

    untitled1.png untitled2.png untitled.png drivers side, I don't see any leaks.
  4. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    let me make this problem/question and thread a bit clearer,
    by asking a few questions, lets clear this up a bit
    "oil looks milky grey white"
    (obviously coolant mixed with oil so your engine coolant is getting into the engine oil)
    "I blew out the heater core."
    (heater core blowing out is very likely due to excessive heat and pressure, but not necessarily due to the wrong head gasket)
    looking at the pictures of the heads its obvious that the cylinder (4) has what APPEARS TO BE, a steam cleaned valve that looks significantly different than the other 3-of the -4 cylinders on that head, the head gasket looks ok, so ID inspect that port and cylinder closely for micro cracks
    (especially in the valve seat on both valves are or where any porting or valve spring or seat machining was done)
    from what I see I don,t think this was the head gasket fault


    Last edited: Mar 27, 2016
  5. Tom

    Tom 69 vette big block

    pass2.png driver retake.png I think that's my flash, Another pic different lighting .
    first pic is the passenger side looks like 6 and 8 where not running or are washed but again the gasket looks ok to me.
    2nd pic is a retake of the drivers side head.
  6. Tom

    Tom 69 vette big block

    another pic of the passenger side # 6 and 8 looks to clean and also header pipes on those cylinders are clean. not running or washed? pass resized.png
    I did towel #4 a little
  7. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    I don,t see any indication the head gasket failed in those pictures,
    your engine may have over heated,
    but I doubt it was due to a head gasket failing from the visual evidence.
    I think your head gasket felpro 1027 headgasket was fine!
    and its bore size more closely matched the intended 496 BBC application

    Manufacturer's Part Number:1027

    Part Type:Head Gaskets

    Product Line:Fel-Pro Performance Head Gaskets

    Summit Racing Part Number:FEL-1027


    Bore (in):4.370 in.

    Bore (mm):110.998mm

    Gasket Material:Steel core laminate

    Compressed Thickness (in):0.039 in.

    Compressed Volume (cc):9.700cc

    Lock Wire:No

    Quantity:Sold individually.

    Notes:pre-flattened copper wire.
    For Aluminum heads only.
    Will not fit Gen V or GEN VI blocks.


    Manufacturer's Part Number:10171

    Part Type:Head Gaskets

    Product Line:Fel-Pro Performance Head Gaskets

    Summit Racing Part Number:FEL-10171


    Bore (in):4.540 in.

    Bore (mm):115.316mm

    Gasket Material:Steel core laminate

    Compressed Thickness (in):0.039 in.

    Compressed Volume (cc):10.346cc

    Lock Wire:No

    Quantity:Sold individually.

    Notes:pre-flattened steel wire. Will not fit Gen V or GEN VI blocks.

    IF I was looking to solve that Id have a trusted machine shop crack/flaw test both heads before reassembly and I would not use the larger bore opening head gaskets, but I would re-assemble the engine with head gaskets sprayed damp on both surfaces with copper coat spray, Id start and run the car for the first 30 minutes with a running garden hose running water over the closed and properly filled radiator and have a large fan providing additional air flow to enhance cooling and Id watch the gauges constantly, and I,d shut it off and check for water in the oil every 3-4 minutes.
    the water or coolant in the oil came from some where the most likely source I see, in most cases is a coolant to oil cooler leak ,
    or a crack in the block or heads

    Id also suggest drilling the T-stat after replacing it with a new one, on the slim chance it was defective, and verifying the water pump that your using is designed to spin in the proper direction, (remember they make both designs (Count clock- wise and clock-wise)and verify the radiator coolant tubes are clear, inside
    remember the head bolt or stud threads need sealant!

    keep in mind the head gasket bore must be larger than the block bore diameter and in spite of printed directions suggestion installing the gaskets dry in most cases , I install all had gaskets sprayed with a good damp coat of copper coat on both surfaces and torqued in place while damp/tacky, after first carefully cleaning with acetone and drying surfaces on heads and block.

    the heads and block surfaces must be very carefully examined for damage or warping issues and if found those issues must be corrected, before any new head gaskets installed, over time steam can and will cut grooves in even cast iron blocks and rather easily in softer aluminum. no head gasket will seal a badly machined or warped head or block

    btw if youve managed to blow a head gasket on a 1986-91 TPI corvette with aluminum heads
    the heads and block surfaces must be very carefully examined for damage or warping issues and if found those issues must be corrected, before any new head gaskets installed, over time steam can and will cut grooves in even cast iron blocks and rather easily in softer aluminum.

    keep in mind coolant must have the anti-freeze ratio set at 50%water 50% antifreeze and be replaced at least every 4 years MAX to retain its anti corrosive additives
    the stock 1986-91 tpi head gasket FELPRO HS7733pt9


    Last edited: Mar 27, 2017
  8. 87vette81big

    87vette81big Guest

    I always Wondered if You could spray Permatex Ultra Copper Spray on Fel -Pro Printo Seal Street series Headgaskets & Fel Pro RACING Headgaskets Grumpy.
    I have always installed the Fel Pro Head gaskets Dry.
    No Coolant leaks.
    But under high Boost pressures or Big Nitrous shots you need extra insurance always .
    I will remember you can apply Ultra Copper Spray.
    Its Good Stuff & I like it.
  9. Tom

    Tom 69 vette big block

    Took the heads to my machine shop to have checked, He also loaned me his torque plate to bolt
    onto the block to pressure test each side, no leaks found, no bubbles at 35 psi and no water running out of oil pan.
    All the head bolts in this Merlin III block are blind .
    I have a bore of 4.310. The 2 fel-pro gaskets that Edelbrock recommends for my heads are 4.370 bore and 4.540 bore.
    Calling edelbrock the teck asked his engine builder about my leak and he said to install the 4.540 gasket and my coolant leak will go away.
    I don't understand why as the gaskets are the same except for the bore.
  10. 87vette81big

    87vette81big Guest

    I am suspecting un even Clamp load is present.
    Troubleshoot required yet.

    Micrometer check the Crushed thickness of your old used Fel Pro headgaskets.
    As many places as possible .
    Around each fire ring.
    Around the water ports.
    Make a Hand written schematic on a sheet of paper.
    All measurements should be within .002" -.003 " or Less.
  11. 87vette81big

    87vette81big Guest

    An mis calibrated torque wrench will do it.
    I don't trust modern electronic torque wrenches....
    I was told recent they are Superior....
    SNAP ON Click Style what I have & Use.
  12. Tom

    Tom 69 vette big block

    Looking at my BBC Merlin III iron engine block there are NO water ports in the right rear of the block and the left front of the block.
    My Blower manifold has NO rear coolant ports at all, it just has a threaded hole on each side maybe for a temp sensor, so if I am correct my coolant is NOT flowing? see pics please

    Attached Files:

  13. 87vette81big

    87vette81big Guest

    Wait for Grumpy.
    I see what your seeing Yes.
  14. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    IN both the big block and small block engine in most configurations ,(the LT1-LT4 uses reverse flow where the heads get coolant first)
    IN MOST CHEVY V8s COOLANT FLOWS in to the front of the lower block,from the two exit ports in the water pump,
    where it separated into the two cylinder banks,where it travels along the cylinder walls,
    once the lower blocks full, then coolant travels upward through the holes in the block deck into the heads where it travels ,
    around the combustion chambers and under the valve train,where the majority of engine heat is produced, then the coolant is constantly being replaced from the cooler coolant flowing upward, so the hotter coolant is forced forward in the head casting,where it flows back forward ,
    where the flow of coolant enters a forward intake manifold passage to reach the t-stat , there it recombines from from each bank, flows up through the t-stat and back into the upper radiator
    thus nothing in the port locations depicted, in those, posted pictures has any effect or restriction to engine cooling, look at the diagram, or presents a problem
    Last edited: Apr 2, 2016
  15. Tom

    Tom 69 vette big block

    Thanks for the diagram, so all is ok with my water ports.
  16. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    yes, your engine cooling issue is located elseware
  17. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    the reason the input and exit ports on most radiators are on opposite sides is so the coolant or anti-freeze, fluid is forced to o cross through the cooling flow tubes, with the heat dissipating fins , but this can also be accomplished with internal baffles in the radiator.
    but your "over heating" issue
    sounds like a blown head gasket or crack in the head or block,

    Last edited: Jul 8, 2017
  18. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    it may be the result of a crack in the head or block or just an intake or head gasket leaking, issue, as stated change oil and filter ,
    and if the problem returns you darn sure better track down the source before repairs get exponentially more expensive
    some cracks won,t leak until the engine heat of the engine thats been running for awhile expands the metal.
    if its not up too operating temp, theres no leak.
    its not un-common for intake gaskets to leak coolant,
    into the lifter gallery if they were not correctly installed or damaged, or intake manifolds to leak coolant,
    be aware that head bolts enter the block coolant passages,
    so if you failed to dip the bolt threads in sealant when they were assembled,
    through the heads coolant can seep up along the head bolts,
    into the area under the valve cover

    btw read this


    both of these work great at sealing head bolt threads, IF you forgot to use thread sealant on the head bolt threads, why, not try to eliminate one potential area of concern,why not pull each head bolt one at a time and clean its threads dip the clean bolt in the can of sealant and re-install and re-tighten the individual bolt to the required torque, before removing the next bolt, I've done this in the past when guys failed too seal the bolt threads and its worked and there was no head gasket issues later, the only thing you have to loose by trying this is the cost of a can of thread sealant and an hour or two of your time, and of course you'll more than likely need to re-adjust valves as the rockers will need to be removed at some point in the process..
    if the coolant passages are corroded or improperly machined,thats an additional potential issue

    found this gasket over at summit..
    using the correct head gasket too match the heads and cylinder heads your using on any big block chevy engine, is critical to prevent coolant loss, and maintain proper cooling


    Brand Fel-Pro
    Manufacturer's Part Number Q8180PT2
    Part Type Head Gaskets
    Product Line Fel-Pro Head Gaskets
    Summit Racing Part Number FEL-8180PT-2

    Bore (in) 4.370 in.
    Bore (mm) 110.998mm
    Gasket Material PermaTorqueMLS
    Compressed Thickness (in) 0.039 in.
    Compressed Volume (cc) 9.700cc
    Lock Wire No
    Quantity Sold individually.

    According to summits apps page

    The gasket your have fits


    Engine Type V8
    Liter 6.5
    CID 396
    Engine Size 6.5L/396
    Beginning Year 1966
    Ending Year 1970
    Engine Family Chevy big block Mark IV

    Engine Type V8
    Liter 6.6
    CID 402
    Engine Size 6.6L/402
    Beginning Year 1970
    Ending Year 1972
    Engine Family Chevy big block Mark IV

    Engine Type V8
    Liter 7.4
    CID 454
    Engine Size 7.4L/454
    Beginning Year 1970
    Ending Year 1990
    Engine Family Chevy big block Mark IV


    or too find coolant leaks if the wrong head gaskets were used.


    Coolant Routing Mk IV/Gen 5/Gen 6
    There are two different ways that coolant can be routed through the engine: series flow and parallel flow. Both ways work just fine. There may be a slight preference for parallel flow, but it is not a big deal. Series flow has the water exiting the water pump, flowing through the block to the rear, it then transfers through the head gasket and into the cylinder head through two large passages on each cylinder bank at the rear of the block. The coolant then travels from the rear of the head, forward to the front of the head, into the intake manifold water passage and out past the thermostat and thermostat housing. The water cools the block first, then it cools the head. The coldest water (coming out of the water pump) is directly below the hottest water (having already picked up the heat of the block and the head) as the hot water transfers into the intake manifold. By contrast, parallel flow has the water exiting from the water pump into the block, where a portion "geysers" up into the head between the first and second cylinder, another portion "geysers" up to the head between the second and third cylinders, another portion geysers up to the head between the third and fourth cylinder, and the remainder transfers to the head at the rear of the block. The coolant temperature inside the engine is more even that way. The differences in coolant routing is having (or not having) the three additional coolant transfer holes in each block deck, and three matching holes in the head gasket. The heads have passages for either system, and are not different based on coolant flow.

    Be aware that gaskets that DO have the three extra holes between the cylinders often have restricted coolant flow at the rear--instead of having two large coolant transfer holes at the rear, there is only one, and it's the smaller of the two holes that remains. This is important because if you use a parallel flow head gasket on a series flow block, you can have massive overheating and there's NOTHING that will cure the problem except to replace the head gaskets with ones that don't restrict flow at the rear of the block, or to drill the block decks to allow the coolant to flow into the head between the cylinders. Here's why they can overheat: A series-flow block doesn't have the openings between the cylinders, no coolant can flow up to the head there. The gasket may only have the single, smaller opening at the rear, so the amount of water that gets through that opening is greatly reduced from what the block designers intended. The result is that the coolant flow through the engine is only a fraction of what is needed.

    Most, but NOT all Mk IV engines are Series Flow. ALL Gen 5 and Gen 6 engines are Parallel Flow. A series flow block can be converted to parallel flow by drilling 3 holes in each deck surface, and then use parallel flow head gaskets. You can use the parallel flow gaskets as templates for locating the additional holes. It's really easy: Put the parallel flow gaskets on the block, mark the location and size of the three extra holes. Remove the gasket. Grab a 1/2" drill and a drill bit of the correct size, and pop the extra holes in the block. There is NO modification needed on the head castings. Some blocks have one of the holes already, but it needs to be ground oblong to properly match the gasket. Again, very easy with a hand held die grinder and rotary file.

    I'd assume the intake gaskets are the source until proven otherwise.
    but be aware that miss matched head gaskets, to the heads and block combo in use, can cause several issues

    don,t assume the worst, just logically and step by step track down and correct the issue using FACTS.
    The Gen V was first installed in the 1991 year models.
    The earliest casting I've decoded was a very late (Nov/Dec?) 1989 date.

    The Gen VI was first installed in the 1996 year models.

    The cams for the Mark IV and Gen V are interchangable for flat tappet lifters.
    The Gen VI where the first equiped with Roller Lifters, but the main difference is the machined flats on the lifter bores of this block - you can still install an earlier cam without rollers.
    The cam retainer plate holes are verticle on a Gen V~VI, rotated 90deg from the Mark IV's horizontal orientation.
    The '91 on trucks with Gen V's had manual transmissions and use a bracket for the pivot, the later medium duty trucks have a hydraulic clutch.
    The Gen blocks use longer main cap bolts than the Mark blocks.
    The crank on the Gen engines uses one long key in the keyway slot for the cam drive gear and the damper - the Mark cranks have two short keyway slots and two seperate keys, one for the cam gear one for the damper.
    As he stated, Gen cranks are one-piece seal, Mark are two-piece.
    The Flex plates are interchangeable - but Flywheels, for truck and marine applications, are not interchangeable on Mark and Gen engines.





    Last edited: Aug 11, 2017

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