Ugh. Yeah...

 

Since you're in there, as you say, now is the time to install a block heater if you think you'll ever need one. They are very nice when the temp is -20*F and the coolant temp is 100*F! If you remember to plug it in, that is!

 

After numerous delays, I finally (FINALLY) got the new head on and the engine put back together last night. FYI, the crack on the original head wasn't in the notorious space between the third and fourth cylinders; mine was at the first cylinder. Anyway, I've only driven it a few miles since finishing the job, but so far it sounds great and runs smooth. Thanks to everyone who offered guidance along the way. The job would've been much tougher without your feedback.

However, I'm still not convinced that I'm out of the woods, quite yet. This was something that I noticed before I did this job, but after running for a little bit, my oil pressure gets up between 30-40 while driving, but drops all the way down to 12ish at idle. That seems low to me, and it hasn't changed since swapping the head. Did I just waste a new head on a motor that needed to be replaced, or is that pressure range normal? Could it be the sending unit? Oil pump? Something else? If some of you who have followed this thread think it'd be better to get more eyes on this question, I'll put it in a new thread. Otherwise, if you have any ideas, I'd love to hear them.

Oh, almost forgot. My front driver's side brake caught on fire during my first drive. Literal flames shooting out through the wheel. Caliper locked up while the Jeep sat for a while. Not sure why.

Thanks as always, everyone.

 

Mines been idling at around 8-9 psi for 3 years but at 65 going down the road is around 60psi...don't sweat it these are low oil psi motors. Verify your readings with a mechanical gauge.

 

Jeep FSM
Oil pressure 4.0L
13 psi at idle
37-75 psi at 1600 rpm and higher.