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Old 12-01-2012, 10:08 AM   #1
Mypantera's Avatar
Join Date: Oct 2012
Location: Harrisville RI
Posts: 169
cracked Head?

I have a 98 wrangler 4.0 that I bought with a bad rear freeze plug. I fixed the freeze plug and got the engine running which I then found I had a blown head gasket (wet plug on cyl #3, lots of white smoke and pressure building in the radiator). I replaced the head gasket last weekend and still have the pressure in the radiator after running for 30 seconds and lots of white smoke however all 6 plugs are dry so now I am confused as to what could be the problem. I pulled each plug and cranked over the engine looking for fluid to squirt out of the head and got nothing on all 6....

Shouldn't there be fluid in the cylinders if the head is warped or cracked or is there another passage for the coolant to get into the exhaust and radiator???

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Old 12-01-2012, 12:15 PM   #2
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Join Date: Oct 2012
Location: Harrisville RI
Posts: 169
never mind.... pulled the head and can see the crack between cylinder 3 and the water jacket.....

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Old 12-01-2012, 03:49 PM   #3

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Join Date: May 2011
Posts: 761
Bad freeze plug to me means neglect,poor preventive maintenance.Rear freeze plugs are mostly protected from external elements,mostly corrosion.Freeze out plugs are named after what happened to your engine.The plug will take up the freezing of the block and pop a plug to save the block.Your case your plug and head went.I wouldn't spend the$$ on rebuilding the head without magnafluxing the block first.Which means total disassemble,clean,then mag.block.Your engine must have been frozen at one time or overheated big time.
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Old 12-01-2012, 04:39 PM   #4
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Join Date: Oct 2012
Location: Harrisville RI
Posts: 169
Dale 3...

The freeze plug didnt actually pop out, it rotted from the inside out. I agree most likely from poor maintenance on the PO's part. When I took out the plug, there was a large pile of sand / dirt piled up against the plug. Probably the cause of the plug failure. I think that once the coolant got low the PO kept driving it which caused it to overheat and crack the head... I wonder if he was even aware that there is a gauge to tell you how hot the engine is...

I did replace all the freeze plugs and the others were all still in really good shape besides the last one closest to the firewall (on the side of the engine). That one had about another week or two before it was ready to start leaking...

I have a rebuilt head on order so next weekend I will put it on and hopefully nothing else is wrong....
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