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  1. #1

    Default Intake Manifold leaking antifreeze - advice needed about repair

    Hello all. My '98 Silverado (5 liter, V-8, 142k miles) is leaking a small amount of antifreeze at the intake manifold. I'm pretty sure I have some oil showing up on my radiator, too - or it realy needs to be flushed. I'm a pretty good weekend mechanic, but this will be getting into something I've never done. It sounds easy enough - get everything out of the way, remove probably 6 or 8 bolts that hold the intake manifold on the engine, get the old gasket off and clean that surface, install new gasket and use a torque wrench to reinstall intake manifold. Suggestions? Am I on the right track? Hopefully I don't also have to remove valve covers or anything else? I didn't see any threads here addressing this, but I am wiling to do plenty of research before I began rather than screw something up.

    Other thing I'm wondering about is: products on the market, i.e., "Thermagasket" and others. I'm concerned that although these products might fix my leak, isn't there a good possibility that they'll gum-up other parts like maybe my water pump?

    Thanks for your help.

  2. #2

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    Where do you have antifreeze on the intake? Can you take a picture? If it is all original, it is unlikely to get an antifreeze leak there,, unless things are so corroded that metal/aluminum has eaten away enough. It is likely a heater hose connection, thermostat housing or radiator hose.

    If you do pull the intake, you are on track with your thoughts above, but it is usually easier to do with valve covers off. You also need to pull the distributor.
    Mark
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  3. #3

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    The antifreeze I see is in the front, underneath the thermostat housing. The guy that inspected the truck in December also told me antifreeze was leaking at the "intake." Maybe it is an easier repair and I'm anticipating worse case scenario. I can take a pic, but not sure how good it wil turn out. Is there a way to figure this out or no I need to just start taking stuff off until I figure it out?

  4. #4

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    It is probably the common intake gasket failure caused by extended life coolant. The EL coolant eats the gasket material over time. Don't ever use any kind of "leak sealer" on ANYTHING... EVER!

    It is not that big of a deal to do the intake gasket. If you have never done one before, make sure to take note of how everything comes apart and make every effort to put everything back without haveing any "spare parts" left over when you are done. Take your time and pay attention to what you are doing and you should be fine.
    "It went together didn't it? Well then there has to be a way to take it apart!" - Me.

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  5. #5

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    If it is under your thermostat housing, I would start with pulling the thermostat, replacing with new one and re-gasket that. Also, check your thermostat housing for corrosion, and your radiator hose.

    In fact, you might try tightening your upper radiator hose anyway. I have seen plenty of them leak a little that would drip down the thermostat housing and to top front of engine.

  6. #6

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    if you do end up replacing the gaskets make sure you get the new updated green ones ;0
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  7. #7
    Jr. Mechanic LoneWolf'burban's Avatar
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    Intake gaskets are easy. Just be easy on it if it's a two piece manifold. 10 INCH pounds to hold down the upper piece.
    1992 GMC Sonoma GT 4.3
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