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Thread: Newly Assembled 304... Head Gasket Leak

  1. #1
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    Default Newly Assembled 304... Head Gasket Leak

    Question:

    I just assembled my newly refurbished AMC 304, and it ran well until it got warm. I noticed there is a small coolant leak between the heads and the block (by the smoke on the exhaust manifold)...

    Does anyone have any advice as to what I could have done wrong? I used the felpro blue/silver type head gaskets (no rtv). Both the heads and block were cleaned well and inspected. The only thing I can think of is "less than perfect" torqueing on the head bolts.

    Changing a head gasket at this point won't really be that big of a deal considering the hours I already have into it...
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

  2. #2
    Registered richardoutwest's Avatar
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    How "warm" did it get? Was the heads torqued in proper sequence and to spec?

    I think I would pull the heads and check once again to be sure they are indeed "flat" as with the block. With the Felpro gaskets being new, they may still be in a condition that you could pinpoint the problem area to look at.

    I hate to hear about thing like this, good money and time wasted. Good luck
    Keeping it on all FOUR!

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    it was near op. temp... maybe 160 F.

    Just saw small drops of green around the head, accompanied by the smoke.

    Like I said. Getting the engine in and out of the Jeep was by far the hardest part... and I assembeled the engine from scratch. I could have the heads back out in prob. 30 mins... Maybe I should have them checked for flatness like you said, them possibly have them decked if needed...
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

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    I also noticed when i torqued the head bolts that some of the bolts were not torquing evenly... i.e. the torque wrench would not turn all the same after 80 ft-lbs, but still all break at 110 ft-lbs... I spent a lot of time cleaning the head bolts, but maybe there were some metal chips in the head bolt holes... (This is all hindsight of course, after you think you've done everything right)...
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

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    I remember when I put new head gaskets on my 304 yrs ago and started it up it leaked--enough that it really scared me--like I really screwed something up. I posted a thread and just tried to find it--and couldn't find the thread back in 2003-2004--result was after the engine warmed up a few times and everything seated the gaskets sealed with no leaked--hope this is the same for you--good luck
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  6. #6

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    Loosen all your head bolts and retorque in SEQUENCE...
    Go about 35 Ft.Lb. the first pass,
    Do about 65 Ft.Lb. the second pass,
    And bring them up to full torque the THIRD PASS...

    SEQUENCE and 'Steps' will chase any 'Wrinkles' out of the heads,
    Gives air spaces time to migrate to the outside of the head gasket and escape,
    And generally makes for a fool proof way to keep head gaskets from leaking.

    If you used 'Fel-Pro' BLUE gaskets, you can retorque without issue.
    If you used the steel shim gasket, you will have to replace it since they don't take loosening and retorqueing well.
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    Thanks for the great info. I will give it a go retorqueing the head bolts. I attached a pic of a 'similar' head gasket which looks just like the ones I used to make sure it is ok to retorque.

    I plan to just slightly loosen the intake bolts, then retighten after I do the head bolts. This should be ok right?

    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

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    If you didn't "Chase" the head bolt holes, it's not a bad time do do it. This is simply running a blind tap down the bolt hole to clean up the threads from debris, burs, etc.. Blow out the debris with air.

    Also, take a good look at the head bolt threads.... a very up close and personal look. I use a magnifying glass... and another bolt thread nestled into the examined bolt threads as reference. You may see that the threads are somewhat deformed, maybe even stretched. Some head bolts deform under torque and that causes the thread deformation. That, in turn, causes the torque setting to be thrown off.

  9. #9

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    Did you use new head bolts? I have heard some people say you can reuse head bolts for one reuse but some people just buy new head bolts as not to take any chances???

  10. #10

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    New head bolts are ALWAYS a good idea,
    But don't buy from 'Discount' places.
    SPS, ARP, Milodon, in that order if you can find them.
    BIG difference between head bolts out there, and some places just make them better than others.

    If you have a 'Leak', you WILL have to loosen he head bolts all the way up.
    You have to chase out the air/moiture that is trapped in there,
    and just loosening them 30 Ft.Lbs. won't allow for that.

    Personally, I'd remove the heads, clean everything up, and use new head gaskets, but I'm a REAL stickler about engine building.

    Chasing the head bolt holes is a MUST!
    You CAN NOT leave crud in the threads or you won't get correct torque readings.

    Head bolts need a light coat of lubricant to torque correctly,
    Engine oil works find, and don't forget to lubricate UNDER the head,
    The head produces friction also!

    DO NOT use something like break in lube or camshaft lube for this!
    It will reduce the torque to the point you will strip the head bolts out before you reach specified torque in some cases.
    DON'T TAKE THE CHANCE!
    Dip the threads in plain old engine oil, let them drain off so they are just coated, and install them.

    And remember! you have at least ONE head bolt that is drilled into a water jacket, so that one will need head bolt sealer before you install it!
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    Thanks for all the great info! I was able to pull the heads off today (1 hr flat... Im getting good at this), and have to wait until tomorrow to reassamble to wait for the head gaskets to come in.

    Could you give me a little more detail about where the coolant flows across the head bolt?? I looked with a flashlight for a couple minutes on the heads, but I can't see where the coolant would flow across at all. The Chilton's manual says there are four bolts at each head where this occurrs...

    So if i missed where it could be, how would I seal that?
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

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    Also, if the coolant runs across the tapped holes in the block, how do you properly lubricate the threads, and apply sealant at the same time....?

    Also, are there supposed to be locating pins in the head or block? It looks like there may have been at one point, but there are none now. Is it ok to install without them??
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

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    Has anyone installed heads on a 304?

    Can you let me know how to seal those bolts...?

    Im gonna install them in about 4 hrs.
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

  14. #14

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    You get a tube of head bolt thread sealer at the parts store.
    Use oil under the heads of the bolts, the sealer will lubricate the bolt threads for proper torque.

    You are wasting your time if you don't take a bolt to the parts store and get a correct tap to clean out (Chase) the bolt holes out and clean the threads of the bolt with a wire brush REALLY WELL.

    Oil the threads in 'Blind' holes, use sealer in the 'Wet' holes.
    Lubricate under the caps of the bolts.

    DO NOT use something like camshaft or bearing lube, this will reduce your toque value too much and you will strip holes or twist bolts off.
    Plain old engine oil will do, but you don't want them dripping wet.
    Dip the threads, let them drain on a paper towel until you are ready to install.
    REMEMBER!
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  15. #15
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    Runs perfect... No Leaks!

    Thanks for all the help!
    1976 CJ-7, 304, T18, D20, 35" w/ locked axles, SOA...

  16. #16

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    EXCELLENT! Glad to hear it!
    See you on the trails!
    REMEMBER!
    Information you got for free off the internet is worth EXACTLY what you paid for it!
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    I used to be TeamRush, but I'm much better with medication...

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