Head gasket ??

Discussion in 'The Garage' started by BLZN4FN, Sep 16, 2006.

  1. BLZN4FN

    BLZN4FN 1/2 ton status

    Dec 19, 2000
    Likes Received:
    Englewood Colorado
    Ok I should know this answer but i'm drawing a blank here. I just bought a 89k5 350 for 50 bucks.

    It's blowing white smoke. I checked the oil and its full of antifreeze how do I tell which side headgasket is bad? I think I will replace both while i'm in there
    but just want to figure which side is bad or maybe a bad block but cant remember how to check.

    Also will a blown head gasket cause the engine to have a ruff idle?
  2. diesel4me

    diesel4me 1 ton status Premium Member

    Jul 24, 2003
    Likes Received:

    Do a compression or leakdown test...yes,a blown head gasket usually causes a rough idle,but so can spark plugs fouled with tranny fluid from a blown modulator valve,which also makes white smoke!..(if you have a 700R4 tranny,it has no modulator,so disregard that if you do!)..

    It would be easy to tell which bank has the blown gasket if it has dual exhaust..but the spark plug will be super clean in the cylinder thats leaky,and will likely have prestone on it..

    I've found a few bad head gaskets with a vacuum gauge,and others by watching for coolant to be blown out of the spark plug hole in the suspect cylinder..sometimes it'll blow between 2 cylinders,and both suffer compression loss..I've seen blocks eroded and rendered useless from the flame travelling between the 2 cylinders on a few motors..:doah:

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