Two freeze plug blow-outs on two rebuilds in 6 months

Goosedog

Member
Joined
Apr 1, 2011
Location
Pisgah Forest, NC
My first rebuild on the 4cyl L-134 Hurricane motor in my '63 Willys last spring ended my relationship with my mechanic after a number of failures, one being a blown out original OEM freeze plug (in the 1st 50mi) that he neglected to change out when boiling the block. That resulted in a warped head which he repaired. But due to also discovering metal in the pan, I took the Jeep to another shop for another rebuild since my confidence was shattered in the first mechanic.

So after a couple hundred very happy miles on rebuild number two from mechanic number two, I had another freeze plug blow out this morning. I didn't see the temps soar as bad as the first time and don't think I warped the head again but what the heck is going on?

I had told the 2nd mechanic all about the first guys failures and so he even JB Welded the fresh plugs in on the 2nd rebuild just for added insurance. I have to believe theres a common denominator here but I'm clueless as to what it could be. The original plugs lasted almost 50yrs and blew out with the first mechanics rebuild, but maybe now it wasn't his fault. I had put a new 7lb psi radiator cap on a year before the 1st rebuild without any issues. Any guesses?
 
the freeze plugs for these engines are convexed and get pressed in placewith the convex out.Then the center is hammered inwards to expand it into place.A brand of tractor used the same style plugs. The first one I see after 50 years.The second one might have went if he used the original style but didn't dimple them in.
 
I've seen some from Dorman made in China and they were not the exact size. Try to find some old stock and check the diameter closely. I coat mine with permatex #2.
 
I want to say it might have been either International or Allis-Chalmers that used the same style plugs.I can't remember at this time.
 
might want to contact Walck's and talk to them about the expansion plugs.They are very knowledgeable and friendly.
 
Got the jeep back to the engine rebuilder, one of two freeze plugs gone, head gasket blown, head possibly warped. Mechanic didn't exactly admit to faulty or improperly installed freeze plugs but he is comping me the work of getting it fixed. I guess that's an admission of sorts right there and all I need.
 
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