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Thread: Copper Head Gaskets Not Sealing Off Water

  1. #1
    I cannot get copper head gaskets to seal around the water ports. I have built a few engines now with copper gaskets BBC and SBC and everyone of them milk up the oil.
    It is not coming from the exhaust
    The block is o-ringed
    The gasket is the correct thickness for the height of the o-ring
    Have used hylomar and permatex #2
    What is next?

  2. #2
    Block seal. Something like KN block sealer or Moroso. Add to a bucket of water and re-circulate like it would in a car. Follow the instructions on the can and you should be able to seal those gaskets.

  3. #3
    Did you use sealer on the head bolts?

  4. #4
    Head bolts sealed very well with Permatex teflon. Thanks

  5. #5
    My copper gaskets are going in the trash. Last run with my blown BBC at 10 lbs. boost, I looked back and water was spewing right out the front of the head. My block water pressure was too high because I throttled back the outlet. The hylomar around the water passages did nothing. I think that with boost and water pressure, the heads lift a little and the copper gaskets have no give. I'm going back to plain Fel Pro, never had a problem. What is your block pressure? A magnaflow pump will blow your seals if it is restricted.

  6. #6
    DJ: I suspect block pressure. I cut all the ears off the cam driven water pump impeller because I could not get any heat (Injected Alcohol), I had to keep the pump on to keep the roller cam from walking out. After it idles and gets heat, I get going and ram pressure keeps it in a good heat range.
    I have a picture of it at top speed. It is shooting water out the #8 outlet 6 feet. It has a # 10 inlet and #10 stepped down to #8 outlet out the transom. I think the ram pressure is just too much for the gaskets.
    [This message has been edited by Infomaniac (edited November 19, 2001).]

  7. #7
    Boy do I have experience in this area !
    #1 run a bypass on the water pressure so that the engine never sees more than 12 lbs.
    You can get them from ARS Marine.
    It helps the engine to heat up better also.
    Hylomar does not seal head gaskets at all.
    Silicone sealer works great but you have to know where to put it. Look at the sealing surfaces between the head, the gasket and the block. In some areas the gasket hole does not match up exactly so you need to make sure you have the sealing surface covered. You don't have to cover the entire gasket with silicone. Make sure you have the head bolts sealed good with a thread sealer. After running a bead of silicone around the water transfer ports I run a bead along the whole edge where a leak could get into the lifter galley area. After haveing the heads on and off 4 times in two seasons I got it down to a science and have'nt had a leak all summer. My oil is totally clean and I am still using the original copper gaskets.

  8. #8
    unchained: Thanks man, I thought about rigging up some kind of bypass and was going to search the Grainger catalog for something that might work.
    The gasket MFG said use hylomar, I should pull it over to them and let them tear it down.
    It will take me a while to work up the proper motivation to tear into it.
    What size inlet/outlet is your bypass valve?

  9. #9
    I agree with the by-pass. I have one on my schiada and it works sweet. I have a water pressure gauge and it never gets above 16psi.
    I have a -16 pick up too!
    [This message has been edited by superdave013 (edited November 19, 2001).]

  10. #10
    I think the water pressure relief valve is 1/2" npt in and out. I set the pressure before I installed it by hooking it up to a garden hose with a T in the line and a gauge before the valve. The brass valve is a pretty basic thing with a t handle which tightens down on a spring and ball. The pressure just lifts the ball and water flows past. I think the valve cost $ 68.00 At cruise speed the valve is bypassing water so it has helped to raise my engine temp also. I'm convinced that most boat engines run way too cold with too thick oil and that costs performance. The Risky Business team uses an oil preheater before they race. KZ told me what weight oil they used and I don't recall it exactly but it was pretty thin, like 5w30.
    Info, Not to be a smart ass, but why do you run alcohol? At the comp ratio and boost level that you run gasoline would be within
    3% of the alcohol hp. Check out the discussion / argument that we had on the blower motors column about that.

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