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Cracked Block?


NAXJA Forum User
Vancouver, Wa.
Ok here's my scenario! I just swapped head gaskets because I had hydrocarbons in the coolant and boil over issues. The head gasket is almost always the culprit right? Welp, I just got it all back together and running and it got up to about 200 and began blasting coolant out of the radiator. I could actually see the compression pulses with the coolant spewing out. The only other option that I can figure is that there is a small crack in the cylinders somewhere that opens up when warmed. Do y'all have any other thoughts besides a cracked block? I've never heard of a cracked 4.0 block!! AAggggh!
Thanks:explosion .

cooling systems pressure tester. a lil pump and line that goes on your radiator just like the cap, pump it up and watch for where the coolant is coming out of.
When you replaced the head gasket, did you have the head and block checked for flatness? Did you use the correct gasket compound on the head gasket? Did you follow the correct sequence and procedure for torquing the head down when you installed it? Did you check the head for cracks?
The head was freshly resurfaced and the block was flat with a straight edge. I used a Fel Pro Printoseal head gasket, they did not recommend using sealer on it. Torqued it right. I'm not new to this, but i'm baffled with this one.

After tearing the head back off, after searching for an hour, I found a small crack in #3 right above the piston at BDC. It's horizontal and about 1/2" long right where #3 and #4 cylinders are siamesed. That explains the whole issue! Bummer, cause it ran good even with 150k!!