I am going to be replacing my cracked 0331 cylinder head and I want to make sure my bearings aren't shot before I replace it. I know that it should be running over 13psi hot at idle, but is there any other way of knowing before hand so I don't throw $$ away replacing the head then finding out the bearings are shot? (besides physically looking at them by dropping the oil pan)

Thanks!

 

first off, where did you get 13psi from?

second does the engine go KNOCK KNOCK KNOCK KNOCK?

 

I have just been reading that. Someone also told on a thread of mine. I guess it is not true??

The engine does not knock. Infact, the engine runs really well at idle before fully hot even with the cracked head.

 

The only way is to drop the pan and use plastagauge on each bearing to check clearance..
So no if you oil p.s.i. is good bearings should be O.K. that is the only way I know.
have fun with the build.

 

Ok thanks!

 

According to the FSM, 13 psi is the correct oil pressure at 600 rpm idle. At 1600 rpm and above, 37-75 psi. The relief is at 75 psi.

 

I would spend $20 and get a mechanical oil gauge to verify psi, if pressure is good, you should be fine.

 

Ok so it looks like I should be ok. I haven't run the jeep in awhile because I do not want to cause anymore damage, but the last time I had it running it would drop occasionally to 30psi at idle.

Do you think I could start it and run it for a few minutes so I can check to oil pressure NOW at idle and NOT do any damage to the bearings?

 

Yes, assuming everything is working correctly other than the cracked head, you will be fine to run it to check oil pressure, but I would say no more than 5 minutes so you don't do anymore damage, cold oil pressure should be higher than it would be warm though.

 

Ok. The only other thing is that the day before the head overheated the jeep the engine light came on and read code

P0302 Cylinder Two Misfire

and


P0455 EVAP Emission Control System Leak

Do these have any relation the head cracking?