Pontiac Repair: 1998 Pontiac Montana 3.4L, pontiac montana, flow restriction

Question
 Had the heads milled and new gaskets all around because of a pin hole in the rear gasket. This was 9000 miles ago. Now the engine is overheating and shuting down.  I check the compression and #1 cly. was 240 psi. and the other five are 175 psi. Started to teardown engine, so far the intake gaskets were in good shape. Have no clue to what the problem is.  Thank you for any help you might offer.

Answer
Hi Joe:
well I don't know why that one cylinder the compression is so high unless there was coolant in the cylinder when you did the test and it skewed the reading. The rear head gasket is always the one that goes bad on these vans I don't know why but they do.. Your gonna have to tear it down further to find the root cause of the leak.. I can tell you if this engine has had repeat overheat issues the engine block is going to be junk! They can's take the overheat cycles It damages the cylinder walls and the rings on the pistons If you do fix the coolant/overheat issue the engine will more then likley start burning oil now.. If the van is worth it maybe you should look into getting a junk yard engine for it rater than dump $ into engine that is going to be doomed... I take it before you started tearing the engine apart that you made sure the cooling fan(s) work and there is no air flow restriction going into the radiator and a/c condenser???
Good luck :)