Coolant leak between head and block

Discussion in 'Engine Topic' started by scrap--metal, Jul 7, 2019.

  1. COPO

    COPO Veteran Member Lifetime Gold Member

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    ^^ and they do work and not clog up the rad ^^
     
  2. Gasoholic

    Gasoholic Veteran Member

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    I was wondering, the heads are brand new but is it a brand new block? New intake?
    I've seen coolant passages on old intakes and blocks get eatin out from antifreeze so that they are larger than normal. The surface might look flat but the cavity could be enlarged from A/F erosion. Maybe not enough surface area to seal tight.
    Just a thought.
    If it was me though, I would fix it. It would bug me and keep me awake at night. And no way in hell I would use "stop leak".
     
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  3. Bandit723

    Bandit723 Veteran Member

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    Video speaks for itself.

     
  4. budro6968

    budro6968 Veteran Member

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    When I first got my Camaro, it had a 305 that had never been run. No break in at all. The cooling system was almost completely full. I then noticed anti-freeze seeping around several lower head bolts. Both sides. Stock cast iron heads. I called the guy that built it in Up north in Mass. He said just fire it up and do the break in. No water in the oil so. I cranked it up and ran the hell out of it with a fan in the front blowing. I ran it for a solid 45 mins with slight variation to idle speed. Mostly kept it up around 1800. Occasionally blipping the throttle. Like magic the leaks stopped.
     
  5. scrap--metal

    scrap--metal Veteran Member

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    I'm happy to report back that Edelbrock was right... After 3 to 6 hours of run time and 6 to 8 heat cycles, the leak between the head and the block magically quit. I'm still keeping my eye on it every time I drive it, but I'm feeling a lot better about the rebuild now.

    Unfortunately, I'm still fighting a coolant leak from the 1/2" NPT plug in the head. I took the plug out and wrapped some Teflon tape around it earlier this week, but that didn't fix the leak. The tape might have slowed it a little, but it's still weeping out of the threads.

    What should I try next? I could repeat the procedure with more Teflon tape; I only used 3 or maybe 4 wraps the first time. Or I was thinking a brass plug might help since the threads should be more compliant than the steel plug I'm currently using. McMaster sells brass plugs pre-coated with some sort of thread sealant. Alternatively, I could try some Permatex thread sealant like this:

    upload_2019-7-25_13-0-1.png

    I'm afraid that thread sealant may act like Loctite though. If it failed to fix the leak, I want to be able to get the plug back out of the cylinder head... Has anyone ever used that stuff?
     
  6. Bandit723

    Bandit723 Veteran Member

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    I use brass plugs and a thread sealant looks like red oxide just can't remember the name off hand and i am at work. looks like this.
    2019-07-25 .png
     
  7. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

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    Contrary to popular believe....Teflon tape is not actually a sealing agent. It will take up the gaps, yes, but seal=no.

    I would try the permatex you show.
     
  8. grasmo

    grasmo Veteran Member

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    ^yes, not a sealant. it was originally designed as a lubricant. use a safe pipe dope...
     
  9. ZEN357

    ZEN357 Veteran Member

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    I would replace the head gaskets with Fel-Pro's to start with and replace the head bolts with ARP's. Best to find the cause then try to patch it.

    Give Summit Racing or Jegs Performance a call, I'm sure they can recommend the correct Fel-Pro Gaskets and bolts.
     
  10. Bandit723

    Bandit723 Veteran Member

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    ^^^^ not sure how replacing the head gaskets will help a leak with a 1/2" NPT plug in the head. :)
     

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