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Thread: Blown Head Gasket - DIY? what else to inspect/replace?

  1. #11
    EFI'd dn010's Avatar
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    If you donít know how old the oil is then change it. If you think itís contaminated then drain it instead of circulating it further. If there is coolant in it, youíll know.
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  2. #12
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    Quote Originally Posted by dn010 View Post
    If you donít know how old the oil is then change it. If you think itís contaminated then drain it instead of circulating it further. If there is coolant in it, youíll know.
    This!

    If the coolent is not mixed, it will come out first. (The oil floats) if it is mixed, it will be milky.

  3. #13
    LS1 DMC Nicholas R's Avatar
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    You should always get hard evidence of a blown head gasket before assuming you have a blown head gasket. Water/Coolant in the oil, exhaust gas in the coolant, significant white smoke consistently coming out of the exhaust, etc. Replacing a head gasket on these engines is not something you jump into on a whim.

  4. #14
    Junior Member JCochrane's Avatar
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    Quote Originally Posted by dn010 View Post
    If you donít know how old the oil is then change it. If you think itís contaminated then drain it instead of circulating it further. If there is coolant in it, youíll know.
    It 100% needs to be replaced as it's several years old at this point, but I figured I'd do that after getting it running, in case I need to drain it anyway for whatever needs to be fixed... Coolant also needs to be flushed & replaced, as I don't know when that was done last either.

    Quote Originally Posted by Helirich View Post
    This!

    If the coolent is not mixed, it will come out first. (The oil floats) if it is mixed, it will be milky.
    Right - oil floats on water - duh. That will make it a bit easier.

    Quote Originally Posted by Nicholas R View Post
    You should always get hard evidence of a blown head gasket before assuming you have a blown head gasket. Water/Coolant in the oil, exhaust gas in the coolant, significant white smoke consistently coming out of the exhaust, etc. Replacing a head gasket on these engines is not something you jump into on a whim.
    I'm so glad I posted here then, at least I hope my fears end up being unfounded...

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    You're going to lots of trouble when one test will show it right away. Get an engine compression tester, pull the plugs, test the compression of each cylinder. If it's as blown as you describe it one cylinder will be way down compared to the others. Also the plug on that cylinder will be super clean or very
    different from the others. Don't give up yet.

  6. #16
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    hello

    i did head gaskets on mine a few years ago when i did the dpi cams.. not too bad if you take your time.. .i just recently did head gaskets on my olds intrigue with the 3.5 shortstar engine and that makes the Delorean engine a cake walk!! .. the olds engine took me and my friend around 30 hrs to complete... the D engine took me maybe around 15.. but i also replaced chains and all that stuff....

  7. #17
    Junior Member JCochrane's Avatar
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    Quote Originally Posted by cdrusn View Post
    You're going to lots of trouble when one test will show it right away. Get an engine compression tester, pull the plugs, test the compression of each cylinder. If it's as blown as you describe it one cylinder will be way down compared to the others. Also the plug on that cylinder will be super clean or very
    different from the others. Don't give up yet.
    Oh, I'm not givin' up that easily - I'll get her running... Good suggestion on compression tester - another thing I haven't done before, but should be straightforward enough I think. So from AutoZone I need an engine compression tester, a radiator pressure tester, and a torque wrench... may be able to borrow the last from a friend instead...

    Quote Originally Posted by painterdave72 View Post
    i did head gaskets on mine a few years ago when i did the dpi cams.. not too bad if you take your time.. .i just recently did head gaskets on my olds intrigue with the 3.5 shortstar engine and that makes the Delorean engine a cake walk!! .. the olds engine took me and my friend around 30 hrs to complete... the D engine took me maybe around 15.. but i also replaced chains and all that stuff....
    Yeah I was thinking 15, split over a few days... was hoping maybe 10 would be enough but probably not good to bet on it - I don't tend to be fast at following detailed instructions on important tasks

  8. #18
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    A definitive test is to test for combustion gasses in the coolant while the motor is running and heated up. A compression test is done cold and it may not leak during the test. If you are blowing coolant out you probably need a head gasket. "Reading" the spark plugs can also indicate a blown head gasket.
    David Teitelbaum

  9. #19
    Senior Member Citizen's Avatar
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    Quote Originally Posted by JCochrane View Post
    I suspect with the engine cool the oil & water will have separated back out, so I guess I probably won't know if it's 'milky' until I drain it empty, or perhaps run the engine for a few minutes to mix it up?
    I believe once the oil and coolant are mixed and become milky, they will not again separate. Oil with coolant in it and then running the engine is like putting them in the blender. Don't run the engine again once you see the oil is milky. The oil will have lost its lubricating property, you're done with it. You'll only see oil and coolant separately if you have not yet run the engine with coolant already in the oil (and of course, you then drain the oil into a pan so you can see it).

    You'll be able to tell if the oil is milky by a quick look at what comes out on the dipstick.

    ...
    Last edited by Citizen; 06-09-2021 at 09:03 AM.
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  10. #20
    Junior Member JCochrane's Avatar
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    Quote Originally Posted by David T View Post
    A definitive test is to test for combustion gasses in the coolant while the motor is running and heated up. A compression test is done cold and it may not leak during the test. If you are blowing coolant out you probably need a head gasket. "Reading" the spark plugs can also indicate a blown head gasket.
    By "reading" the spark plugs, do you mean just taking them out and checking their condition? See if one is significantly cleaner than the others?

    So to check for combustion gasses in the coolant, I need a test kit and test fluid - is the kit usually something I can loan out from AutoZone? I'm assuming I'd have to buy some quantity of the test fluid. And then do I test that at the coolant tank?

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