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  1. #1
    Jr. Apprentice
    Join Date
    Aug 2013
    WESTTOWN NY 10998

    Default Intake manifold leaking on 1998 k2500 7.4 ????

    How do i check to see if my intake manifold is leaking,---thank you

  2. #2
    Caddiac's Avatar
    Join Date
    May 2011
    Upstate South Carolina
    Blog Entries


    I don't know about the 7.4 but the 5.7 in my truck will start to leak every 100,000 miles. By your question, I take it you are having to add water or get a faint antifreeze smell when you get out of the truck after driving a while. But every time you look, there is no water under the truck on on the engine. That is what happened in my case.

    I found mine by sliding under the truck and looking up the back side of the engine. I noticed on the drivers side there was staining on the back of the block that started where the intake bolted to the block. Obviously, keep on eye on the dip stick - a buddy with a 96 Silvy lost an engine when his gasket leaked to the inside.

    The radiators also will start to weep fluid and it is hardly noticeable as well. I am told that the seal between the radiator tanks and the core will leak after a 100k or so. Mine made it to 175K. Again, hard to see if the radiator was leaking because it is so slight is quickly evaporates. And I did not have to add water very often. Finally saw evidence along the left hand tank. Raidator shop said the labor to repair would be close to the cost of replacing the radiator. I found one on line and have put almost 100k on it with no problems.

    Good luck.
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  3. #3


    And if you think you have an air leak, use a propane torch; turn on the torch (do not light it) slowly move it along the intake gasket, if the engine rpms change you have found the leak (the air is replaced with propane which burns change the engine performance).

    '09 Avalanche LTZ - Black
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