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  1. #1
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    coolant leaking from exhaust bolt hole?

    HI everyone, I just picked up a 5.9'er (finally!) but was told by a local shop that was doing some other work that it popped a head gasket...well upon some detailed investigation, it seems coolant is leaking out of the passenger side rear exhaust bolt hole (mike leach headers are installed and ported Magnum RT heads). Do the exhaust manifold holes go through the coolant passages?

    If so - I'm a happy camper with an easy fix
    98 JGC 408 stroker, ported MP heads 2.02/1.60 valves, 408x cam, m1 2bbl intake, ported TB, AEM CAI, Leach headers, high flow cat, Kolak cat back, built APS trans with 2600rpm stall, stock and refreshed 249 t case, front diff, rear diff - fixin' her up!

  2. #2
    Forum CONDUCTOR Man Z88Z's Avatar
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    Just to get the ball rolling....

    Not sure about that but I'll try to take a look at some blocks I have.

    However, even if that's the case and it does go through I don't like the fact that it's leaking from there. Bolts or studs might not be a rock solid seal but I don't think they should be leaking either, or at least not enough to cause much of a concern.

    You might have something more going on there - if that bolt hole does normally go through to the water jacket you might have slightly stripped or 'hogged out' threads that aren't allowing for a proper seal, or (if it was originally a blind hole that didn't go through to the water jacket) maybe it was drilled too deep previously by someone repairing a stud that broke off in there - but I'd still kinda think the threads weren't up to par

    Hopefully it'll be good news and you can find a sealer that will work, worst case scenario (hopefully) is that you might have to have it drilled out and a helicoil installed. Not sure if there'd be enough room to do that with the head and motor in place or not.


    I got it started - hopefully this will bring it back up and you'll get some responses from people that can confirm that or someone that's run into a similar problem

  3. #3
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    Thanks for the input! I should clarify that the bolt is currently missing...so when I put water/coolant in the radiator it literally streams out of the hole like a garden hose! I'll buy some bolts today to see if it seals up with a bolt with rtv but I would still like to hear from whomever knows if these bolts do go through the water jacket...

    Thanks again!
    98 JGC 408 stroker, ported MP heads 2.02/1.60 valves, 408x cam, m1 2bbl intake, ported TB, AEM CAI, Leach headers, high flow cat, Kolak cat back, built APS trans with 2600rpm stall, stock and refreshed 249 t case, front diff, rear diff - fixin' her up!

  4. #4
    Member KJK_Texas's Avatar
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    Quote Originally Posted by drhill View Post
    If so - I'm a happy camper with an easy fix
    The bad news: That head is done.

    The good news: Time for Edelbrock heads!
    5.9 ZJ SCT tuned PCM/ KJK CAI/ Thorley headers with 3" Magnaflow cat and muffler/ Modded kegger/ TransGo shift kit/ Vanco brake kit/ Braided steel brake lines/ Mopar cupholder insert!

  5. #5
    Forum CONDUCTOR Man Z88Z's Avatar
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    Quote Originally Posted by KJK_Texas View Post
    The bad news: That head is done...
    Why do you say that, you think it's something beyond what I described - a crack or something?

  6. #6
    Member KJK_Texas's Avatar
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    Quote Originally Posted by Z88Z View Post
    Why do you say that, you think it's something beyond what I described - a crack or something?
    It's cracked. Maybe from overheating in the past. The exhaust manifold fastener holes do not extend into the water jacket.
    5.9 ZJ SCT tuned PCM/ KJK CAI/ Thorley headers with 3" Magnaflow cat and muffler/ Modded kegger/ TransGo shift kit/ Vanco brake kit/ Braided steel brake lines/ Mopar cupholder insert!

  7. #7
    Forum CONDUCTOR Man Z88Z's Avatar
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    True, could be something more serious like and should be investigated further, but maybe it was just overdrilled during a repair.

    Certainly worth trying a repair on where they're ported RT heads and all

  8. #8
    Huge Member Endless's Avatar
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    If he knew that it was just over-drilled that would be one thing, but hoping that is the case and making a repair without pulling the head to check seems kind of risky to me.
    04 WJ 4.7ho Ltd
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  9. #9
    Forum CONDUCTOR Man Z88Z's Avatar
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    Depends - do you mean risky as in wasted effort or are you thinking something that could cause further damage?

    I'm not saying you guys are wrong, more damage than a penetrated coolant passage is definitely a possibility, although it'd have to be a helluva crack to be pissing out like he described, but no that's not an impossibility by any means.

    I gotta go pull a head off the shelf to see if I'm thinking right here, but it should be pretty easy to confirm the level of the problem one way or the other shouldn't it? ...or at least to confirm whether the head needs to come off for further inspection or repair etc, yes?

    I'm thinking probe the hole and confirm whether or not it goes straight through. If it still ends in a completely blind hole, then ya that head has probably got serious problems.

    If the bolt hole is indeed penetrated into the water jacket, I'm thinking:

    Install a stud or bolt in there.
    Fill the cooling system.
    Pull the nearest plug. Check for signs of coolant etc and leave the plug out.
    Pull the dipstick. Wipe it down and recheck, do your best to memorize the current oil level and reinstall.


    Then pressurize the cooling system cold with a radiator pressure tester.

    Watch for leaks from the spark plug hole and listen for trickling noises at the oil fill cap etc - while mainly watching for an increase in oil level on the dipstick.
    Actually better still, you could take it a step further and drain the oil before this test. Check for any signs of coolant already in there since it sounds like this problem might have been pre-existing. This way is also much better as you'd be able to listen/watch for leaks from down there - you'd know a lot sooner if there was a problem and/or you could be a little more certain either way.


    That should give a pretty good indication of what's going on, yes?

    If it passes that, no leaks out the plug hole or oil drain or depending on how you do it, no increase in oil level - clean and install the spark plug and add oil. Let it idle for a while and get to operating temp, then recheck that plug and the oil level. If it still looks good run it longer, drive it a bit etc. Recheck the plug and maybe drain the oil and look for coolant etc.

    I agree there's the possibility of a serious problem here, but I wouldn't want to write off a ported R/T head or go right to yanking it for inspection based on what he described up there. You guys agree with the testing methods, or no?

  10. #10
    Huge Member Endless's Avatar
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    If it’s simply been drilled out and tapped it should have a larger bolt than the rest right?
    If it’s been helicoiled, would you be able to see the insert with a mirror and flashlight? I don't know?

    I think your tests are a good idea and definitely worthwhile before you pull a head.

    Personally though without some other conformation that it was a drill through, a lack of symptoms right now doesn’t mean that a few heat cycles and several miles later that a crack would propagate or (especially if its been overheated) the HG goes out and you puke coolant into a cylinder or oil and end up with a lot more damage.
    04 WJ 4.7ho Ltd
    98 ZJ 5.2 Ltd

  11. #11
    Forum CONDUCTOR Man Z88Z's Avatar
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    Quote Originally Posted by Endless View Post
    If it’s simply been drilled out and tapped it should have a larger bolt than the rest right?
    If it’s been helicoiled, would you be able to see the insert with a mirror and flashlight? I don't know?

    Personally though without some other conformation that it was a drill through, a lack of symptoms right now doesn’t mean that a few heat cycles and several miles later that a crack would propagate or (especially if its been overheated) the HG goes out and you puke coolant into a cylinder or oil and end up with a lot more damage.

    Did some checking and as KJK said it does not extend into the water jacket. It looks like it comes pretty close though.

    As far as an oversized bolt - not necessarily. I was thinking maybe someone just drilled to far trying to remove a broken stud - worked it out and retapped stock size? Would be easy enough to check the size though.
    Or for that matter maybe someone had a heavy hand and tried to force a bolt that was too long into there, broke through the back? I have no idea if that's even possible though - I'd think the threads would strip before it put that much pressure on the casting.

    The helicoils I'm thinking of are a pretty bright silver, so you might be able to see that with a good light and a mirror if there was one. Not sure how long they stay that color though.

    I think another good measure would be to remove the other header bolts so you can move the flange back a bit and get a better look at the area. Looks for cracks across the bolt hole etc and it might generally give you a better idea of what's going on there.

    I agree that it could be ok for a while, then propogate - but a bad HG is something that could happen on any motor at any time, right? I'd say do as much of that testing as possible - and in this case he'd already know to be on the lookout for any signs of anything like that happening.

    Who knows? Yes it might be junk right now or it might be something simpler that could last a while. I'd do as much testing to confirm it either way before I comitted to relacing that head, or possibly pulling it for further inspection or repair.

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