F Engine freeze plug problem

Discussion in '40- & 55-Series Tech' started by southerncruiser62, Jan 24, 2006.

  1. southerncruiser62

    southerncruiser62

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    Okay so i need some help here. My neighbor has a 72 FJ55, with F engine which just went under a recent (less than 300 mile) rebuild by reputable shop. The problem is this, upon completion of rebuild the engine would start up and then shut right back down. This was solved and now we have this freeze plug issue.

    Issue being this:
    Engine ran well for about 1 hour...it then blew a freeze plug out (not due to freezing). What we believe is a pressure issue. It was then reassessed and the dowels in the head were missing causing the head gasket to be off, and upon ordering installing, pressure testing and new gasket, head was regrinded and reinstalled. Engine ran with no problems for about a week. It now has the reoccuring problem of a blown freeze plug....what we still believe is a pressure problem. New water pump, new thermostate and recored radiator.

    What can be causing this?

    Thanks in advance.
     
  2. nuclearlemon

    nuclearlemon not an addict Moderator

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    i've heard the aftermarket cup style freezeplugs are junk...you have to use oem disc style freeze plugs.
     
  3. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

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    I think the 1972 F engines still used Welch plugs instead of cup plugs. Welch plugs are trickier to get installed & staked properly. Oh, and they need to be the proper metric sizes to have any chance of sealing up. There are young people in shops who do not know what a welch plug is, or how to properly install one.

    Just my thought- simple installation error.
     
  4. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

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    Damn, Ige. You type fast.
     
  5. 3jvj

    3jvj

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    I would have your radiator cap tested. Aftermarket exspansion plugs work in a pinch; I would throw one in the glove box for safe measure. my .02
     
  6. 3jvj

    3jvj

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    Around here you would just skip the freeze plug and throw in a block heater ;)
     
  7. southerncruiser62

    southerncruiser62

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    After posting this and in the meantime searching i have seen that through multiple posts that aftermarket plugs seem to be the issue, esp. the cup style vs. the concave style. I will mention this...thanks again for all the input
     
  8. 65swb45

    65swb45 Supporting Vendor

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    Never mind 'mentioning' it; if it's an aftermarket plug, chances are it's gonna be stamped with it's SAE size. That's how you'll know it's the wrong part.:mad: AFAIK, the OE plugs are still available at the dealership, and they are really not that expensive.

    Hth

    Mark
     

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