I just plasti-gauged my crank bearings and here is what I found. Just outside of tolerance. Do I replace with the same size bearing that was in there? (theory being the bearing had worn and the replacement will be smaller in diameter) I don't have a mic and the engine is still in. I really don't want to pull the thing. I am doing the crank and rod bearings. The plasti-gauge reads .051 and I am just there. FYI, I have oil pressure that drops below 10 at idle. 108,000 miles 4.0L 2000 Cherokee sport. Cracked 0331 head, (replacement coming)

I did torque the bearing to 80 ft pounds and I was really careful about being clean.

 

You don't want to use a different bearing unless you have the crank ground... The new bearings are going to make that tolerance tighter yes... but how much I couldn't say. How does the crank journal look?

Keep in mind plastigauge isn't a good tool to measure wear...

 

The journal looks great. I'm tempted to throw new bearings at it and call it a day. I suppose the only way to measure wear is to mic the crank? *sigh*

I'll grab a new bearing and plasti-gauge that. Should give me some answers right?

Thanks for the reply. I love this forum.

 

Yes and yes.

 

You can see the reman on the head I pulled off. It failed, you can't see the small crack at the bottom of the fix. Based on the quality of the work (or lack thereof) I have found while getting to this part, I am concerned that I will find something major as I dig deeper.
I found that the thermostat was bad (didn't move even in boiling water) and suspect that an overheat, or multiple overheats caused this failure. The coolant was some of the worst I've ever seen. Mississippi mud with chunks of catfish mixed in. A good flush is in order.
New head, water pump, etc are supposed to be hear tomorrow.