Coolant leak behind timing cover.

Discussion in 'KJ General Discussion' started by Crowde, Feb 15, 2020.

  1. Crowde

    Crowde New Member

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    I've tried searching here and elsewhere for a solution but haven't had any luck.

    I'm having a hell of a time getting the coolant channels between the timing cover and the block to seal up water tight on my 2003 KJ 4x4 3.7l Vin K.

    I'm up to 6 or 7 times now where I get everything together and wait the 24 hours only to pour a gallon of distilled water into the reservoir and find it leaks behind the timing cover. I'm not sure if I'm missing something or what.

    I've tried the old style full gasket + O rings from Vincos dry, no luck.
    I've tried the old style full gasket + O rings from Vincos w/ Permatex UltraBlack RTV, No luck.
    I've tried "new style" (just the 3 O rings) w/ Permatex UltraBlack RTV, no luck.
    I've tried "new style" (Just the 3 O Rings) w/ FelPro's Black RTV, no luck. - This multiple times.

    Results have slowly improved from a steady stream of water with the Vincos full gasket setup to just a drip every few seconds with the Felpro 3 O-Rings and RTV, but alas there is still a leak once I add pressure (which obviously doesn't hold) to the system.

    From what I can tell the 2 round O-rings are sealing fine and the issue is the funny-sorta-triangular-shaped gasket on the upper channel (the water falling straight down on to the crankshaft)

    I've tried letting it sit an hour just finger tight before torquing per the Permatex instructions. I've tried torquing to 40-ft/lb right away per the FSM. The latter working better but still not perfect.

    I don't have a precision straight edge but as far as I can tell the timing cover is not warped, because the thin film of RTV being squished between the cover and block seems to be a universal thickness all the way around.

    It doesn't seem to be a problem with the O-rings moving out of place. I get 3 bolts started before mating the surfaces together to try and avoid any shifting.

    There is a small bit of corrosion/pitting in the cutout on the timing cover that the upper gasket sits in. I've tried a couple times adding some RTV around there as well to try and compensate with no luck.

    Am I just totally missing something here? At this point I feel like there's something I'm just totally overlooking or not accounting for.

    Right now my next step is to try MAHLE parts and the Grey Aluminum Silicone RTV that set comes with.

    I'm at wits' end so any help would be greatly appreciated. Thanks.
     
  2. ltd02

    ltd02 Comfortably numb KJ Supporting Member

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    I used the Fel Pro TCS46022 set twice in my 02 and never had an issue. Headgasket replacement the first time and crank and bearings a 4-5 years later. Sounds like something is not mating correctly. Mahle are good gaskets too. I'd give them a try one more time. Just used an upper engine set in my 2011 Avenger and worked great.
     
  3. turblediesel

    turblediesel memberable

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    I don't have experience with the 3.7 but I had to try three times on a ford 302 to get it sealed. Permatex makes a special silicon sealer for the corner and edge seams that seems thinner. Black permatex sticks and seals better than the blue(bad) and orange silicon.

    The trick with silicon gasket sealer is to snug it down (tighter than finger tight) and give it some time to flow and spread so there aren't any high blobs that firm up. About 15 minutes is good, then tighten evenly some more. Keep doing that until you reach the final torque spec. Don't use too much or it'll end up plugging the oil galleries in your engine.

    Good you're waiting the appropriate cure time.

    I've pulled great globs of blue silicon out of broken engines.
     
  4. Crowde

    Crowde New Member

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    Just for reference for anyone that is searching for a solution to a similar problem in the future, I found mine.

    Somehow I'd missed a pinhole leak in the timing cover plug. Permatex Ultragrey + Mahle gasket kit took me the rest of the way.

    So yeah, moral of the story is to triple check things.
     
    Last edited: Feb 18, 2020
    mrlavalamp, ltd02 and uss2defiant like this.
  5. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Glad you found the fix, Thanks for letting us know.