Unstoppable Coolant Leak

Small Block Mopar Engine

  1. Charlesvolare

    Charlesvolare Well-Known Member

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    Bought it brand new a little over three years ago and have had zero issues until recently.

    I had a 16lb cap on at first, then a 7lb. Didn't make a difference. No Roll pins, RTV to seal china walls to intake.
     
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    • yellow rose

      yellow rose Overnight Sensation FABO Gold Member

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      You need to mill the intake. If you need to you may end up using thicker gaskets or double up on gaskets.

      Ive seen more junk, leaky intake manifolds than I care to remember.

      I won't put an Edelbrock intake on an engine I haven't surfaced. I won't even bother to check it. It gets cut.
       
      Last edited: Jul 31, 2019
    • Charlesvolare

      Charlesvolare Well-Known Member

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      Another thing- I've been torquing the intake in two steps to 23-25 ft-lbs (Found here: Dodge Magnum Torque Specs ). BUT, my intake is for the most part a chinese copy of the edelbrock air-gap with both head patterns drilled. I looked up the instructions for that to see how they recommend installing it and they only say to torque to 12 ft-lbs! https://www.jegs.com/InstallationInstructions/300/350/350-7577.pdf
      Did a little more digging and saw a few other things that said that.

      Thinking on this, I realized I was torquing to ~23 lbs initially- small leak. Retorqued to 25lbs (eighth to quarter turn more)- bigger leak. Overtightening may have been borderline okay before, but with the heads milled it's causing havoc not letting the gasket take up the newer difference in angle. I'm hoping I'm onto something with this. When I get home I'll loosen everything and get it to edelbrock's spec and let you guys know if it made any difference. Hopefully everything should still seal.
       
    • yellow rose

      yellow rose Overnight Sensation FABO Gold Member

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      I have never torqued an intake manifold in my life. Not on the Hemi (gen 1 and 2) or anything else. I snug them down with a box end wrench. That's it.
       
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      • Charlesvolare

        Charlesvolare Well-Known Member

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        That's what someone at work was saying. I got in the habit of torquing everything and I guess reading wrong specs can cause problems with that.
         
      • 512Stroker

        512Stroker We are all here because we are not all there.

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        If you really think that your Chinese intake manifold is the problem, get a different manifold.
        Even a new manifold is not that expensive.
        You can spend alot of time and frustration trying to correct what you have and may never get it to stop leaking.
        Bite the bullet and swap it out and be done with it.
         
        Last edited: Jul 31, 2019
      • Charlesvolare

        Charlesvolare Well-Known Member

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        I don't think the manifold is the problem, it's definitely exceeded my expectations. I'm leaning on it being an angle problem that's being exacerbated by being overtorqued. There's not too many intakes out there with the magnum bolt pattern but I've had my eyes on a few for a while now. If I end up needing to I have no problem with grabbing a new one.
         
      • 512Stroker

        512Stroker We are all here because we are not all there.

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        If you think it is a "angle problem" how are you gong to correct it? I dont see changing the angle of the head surface very easily. That would mean correcting the angle on the intake manifold.
        If it is that fair off there is no sealer on the planet that going to fix it, I never was a fan of stacking gaskets thats just a crutch.
        Partner its your time and money but IMO you are chasing your tail.
        It will be interesting to see which path you go down.
        Good luck
         
      • Charlesvolare

        Charlesvolare Well-Known Member

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        I'm not saying the intake being cranked down is THE problem, but if I can spend five minutes (and no money) and loosen a few bolts and it stops leaking I'll call it good. If that doesn't work, I'll continue digging. Next step would be to pull the intake and actually measuring things out and if I need to take something to the machine shop I will. Like I said, I feel like it's an angle problem that's being exacerbated by being overtorqued. No certainty in that at the moment, but it makes sense to me and it's worth a shot. Don't see how I'd be chasing my tale with that.
         
      • 512Stroker

        512Stroker We are all here because we are not all there.

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        Go gett'm Tiger
         
      • RustyRatRod

        RustyRatRod I didn't do it. FABO Gold Member

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        If that's the case, I'd suspect gasket failure. Maybe you need to use a thicker/better gasket as mentioned. Even still, I would check it ALL out as I outlined.
         
      • MopaR&D

        MopaR&D Nerd Member

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        This is what I was thinking too, if Edelbrocks are that bad then a Chinese knock-off can't be any better. Having your intake milled is not very expensive.

        The way the heads sat before being .010" higher than they are now may just have sealed the intake enough, now that the heads are straighter and a bit shorter the fit is worse.

        Hey at least it's not an internal coolant leak going into your oil...
         
      • dano

        dano Evil Handy Man

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        You could remove the intake and gaskets and just set the intake on with no gaskets and see how the flanges line up. Also check to see if the bolt holes line up with clearance. If they are rubbing on the holes you'll get a false torque setting.
         
      • mullinax95

        mullinax95 Well-Known Member

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        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          I'll tell you what I did;
          I removed the intake and cleaned everything. Then I dropped the virgin AirGap intake on with no gaskets. Next I installed some shims on one side followed by two bolts on that side, at the front and the rear, second from the corners, which I snugged down.
          Now I went to the other side to see what was going on...... not pretty.
          In my case the block had been decked so poorly that the virgin Eddies were going uphill to the back on one side and downhill on the other and neither end was at the correct angle. I had to remove the engine from the car and completely tear it down, then send the block out for re-machining.
          Sometimes Life hands you lemons.
          Needless to say, I used a different machineshop.
          Your results may vary,lol.
           
        • pishta

          pishta I know I'm right....

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          12ft/lbs? I been doing AL intakes wrong forever @ 35 ft.lbs. But I never had one leak either.....interesting. Weiand states 25 ft/lbs and also calls out .050-.060 soft composition gaskets for aluminum intakes. I dont think I ever loosened something and had it stop leaking...'cept maybe a Holley 1920 bowl....
           
        • mullinax95

          mullinax95 Well-Known Member

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          In the service manual for 5.9 Magnum it calls for the final torque to be 12ft/lbs. I have a new 408 and when I installed the new Hughes intake I torque them to 12ft/lbs. It did fine for a while but then I started hearing a whistle noise. The intake was leaking on number 6 cylinder intake runner where it meets the head. I talked to a engine builder and he told me to torque the intake bolts to 35ft/lbs. I was hesitate at first but did it anyway. The leak was gone and have put 2700 miles on it with no more issues. So you really can't go by the service manual...LOL
           
        • mullinax95

          mullinax95 Well-Known Member

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          GEEEZZZ.... You have more patience than I will ever have. Glad you got it sorted out. When you had it re-machined did that boost your compression?
           
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          yes it did;
          but I immediately installed a bigger cam, so the pressure remained very similar.
          Oh wait,no, that re-machining happened shortly after the first iteration, and I actually went to a smaller cam...... but a thicker headgasket.... so the pressure remained very similar.lol. That was year 2000.
          I built the engine in such a way that this was possible, cuz right from the get-go, I was aware that the 292/509/108 cam might not be my cup-O-tea. And it wasn't.
          But by the time I had that figured, I sorta knew how much smaller a cam I might like. So I went down, almost 3 sizes; from that 292 to a 270/276/110, and hit a home-run for me.
          After that 270 cam dropped lobes, I went up one size to a 276/286/110 and it's bin in there since 2004. Yeah it's a tad large for me, and I'm waiting for it to self-destruct so I can replace it.... but it's like the Energizer Bunny; it just keeps going and going and going.......
          The compression progression IIRC was 11.3 down to 10.95, and remains there.
          But the pressure has always been close to 180 psi (aluminum heads), with each iteration. I think this 230* cam is around 177.
          I chose that pressure in year 1999 against advice from all other smarter-than-me, mechanics and builders, who, I guess were Chevy guys, cuz 180psi runs just fine in a Mopar,on 87E10. I was prepared to do whatever it took to make that work, but happily, I didn't need to.Several years later I found guys here on FABO running up to 200psi on pumpgas, so 180 is, I guess, still on the conservative side,lol.
          If I had a smaller engine I might try ~195psi and an automatic, cuz my 367 with that 270cam was a torque monster. But 180 is already too much for a manual trans, IMO, cuz I have to take timing out at low-rpm, not because of detonation, but because the power-pulses are just too "violent" to idle around with. So, Ima thinking a 318/340 at 195psi is the next experiment for me, but in a slightly lighter car, like a Duster/Demon/Early-A.
          But making that kind of pressure with a 318 is gonna be real hard, and probably pretty expensive; cuz the total-chamber volume is gonna have to be real small, and of course, the heads will have to be aluminum.
          Ima thinking the 340 will be tuff enough.....
          Meh, the 360 was actually pretty much a bolt-together deal.
           
          Last edited: Aug 1, 2019
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          • Charlesvolare

            Charlesvolare Well-Known Member

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            I took the intake off and cleaned the gasket surfaces. I set it back on the heads and it will rest on the China walls before touching both heads, and I can get a little over .030" of clearance at both ends and the middle when it's butted up to the other head. I'll check it with clay tomorrow and see how that checks out. IMG_20190802_192345.jpg
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            I would think that an even .030 gap would be taken up by the intake gaskets nicely.
            I am no familiar with the magnum configuration.
            Are the intake manifold bolt holes in the head blind or do they extend into the water jacket in the head?
             
          • AJ/FormS

            AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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            There ya go
             
          • Charlesvolare

            Charlesvolare Well-Known Member

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            They extend straight down into the head/lifter valley i.e. If I were to take a bolt out and pour oil down the bolt holes it'd run into the lifter valley. No water jacket. The outside bolts just run to the outside of the heads.
             
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            • Charlesvolare

              Charlesvolare Well-Known Member

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              Does this mean mill the bottom plane? Sorry, got busy and haven't thought too much on it just trying to figure it out. That'd be around .015 each side clearance, gasket is .060" thick so around .040-.045" on each side, it'd lift the intake up a bit. I have a new set of gaskets and I'll set this on tomorrow as well and measure China wall clearance.
               
            • James Clews

              James Clews Well-Known Member

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              i had a edelbrock 340 victor on my small block without any issues then bought a speedpro chinese air gap manifold and put it on but it ran like crap, possibly an air leak in the valley somewhere so I bought an edelbrock air gap and replaced it and have not had any issues ever since. I think the chinese manifold did not have the correct angles on the intake surfaces as I have never had a manifold leak air or coolant before. the quality control of those manifolds appear to be suspect. Change the manifold now!
               
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