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Thread: V8 head gasket questions

  1. 6th May 2012, 08:55 AM #1
    Dave109
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    V8 head gasket questions

    86 3.5 efi Dual fuel. This started useing coolant and building pressure in the header tank which remains when cooled back to ambient temp, running with the cap off shows bubbles in the header tank. Got to be a head gasket I thought and removed both heads, however the pressed steel gaskets and the matching surface on the heads, look fine and no sign of any leakage path.
    I did about 500Km on LPG from noticing loosing coolant, to removing heads, should I expect to see an obvious leakage path? Other question is should these pressed tin gaskets have sealant, manual says no but old one were completely coated both sides?
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  2. 6th May 2012, 12:38 PM #2
    PhilipA
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    The head gasket failure would have to be on 1-7-2-8 ie the end cylinders to pressurise the radiator.

    If there is no failure at the very ends, you would have to suspect a slipped sleeve, whcih while not as common in 3.5s , still happens.

    have a look at the combustion chambers of the heads and see if any look "steam cleaned". If so suspect the sleeve in that cylinder.
    Look to see that all the sleeves are dead level with the top of the block. Any that aren't by even 0.5MM may be slipped and have a crack behind them.
    Regards Philip A
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  3. 6th May 2012, 05:00 PM #3
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    bee utey
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    I replaced a set of steel shim gaskets on a mate's '84 RRC 3.5 for the same reason, the head/block faces had no signs of blowing, engine didn't misfire, and only lost coolant during heavy acceleration type driving. Two new composite gaskets fixed it for another 2 years heavy service. The shim gaskets do not tolerate even the slightest unevenness when they get old.
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  4. 18th June 2012, 06:34 PM #4
    Dave109
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    Bit of an update, heads were dead flat, engine very clean inside, so I put a set of new steel shim gaskets with no sealant as per the manual. Two weeks of usage later, coolant level is not dropping so might be lucky. Glad I made the effort, looked difficult with all the EFI stuff on the engine, but really isn't.
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  5. 18th June 2012, 06:49 PM #5
    PhilipA
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    Great result , congratulations!
    Regards Philip A
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