Oil Pressure Question

Cal.bar, just drive that Jeep. Your oil pressure is just fine. As has been said, it is regulated at 80 PSI maximum, so that is good. Five PSI is the MINIMUM warm idle PSI. So again, your Jeep is just fine. Your re-builder did a good job. They probably machined your block to take the 302 cam bearings. Use the oil they recommend. Warranty.

Larry, Just because the gauge is new does not mean it is accurate. We have seen many new parts that were bad new from the box. Test your Jeep with a known good gauge.

If I am understanding you correctly, you get 30 PSI at cold Idle, you get 40 PSI at cold cruise, & you get 5 PSI at warm idle. What are you getting for oil pressure at warm cruise speeds?

My concern is that you should have a bit more pressure with a freshly rebuilt engine. Five PSI is minimum for a worn engine.

Check the gauge first. Lets make sure that your numbers are correct. I see no sense in chasing a problem that may not exist. That would be a waste of time & money.

IHTH, Cpt Logger.

5W-30W? DOESN'T THIS ENGINE USE JUST 30W? COULD HE JUST BE RUNNING TO THIN OF A OIL WEIGHT?

When my Jeep's 4L134 engine warms up, the idle oil pressure is around 10psi and at 45mph, the oil pressure comes up to about 35psi.  When the engine is cold (well, cold for Phoenix, AZ), the oil pressure is around 60psi.

The bearings in the engine are quite large and it doesn't take much oil pressure to keep the oil film between the bearing surface and the crankshaft surface. 

I run 10W30 oil in the winter and 30W oil in the summer..and add some zinc additive just in case.

I've always felt that a lot of engine bearings were ruined by using a very heavy oil on a cold day.  The pressure reading measured in the relatively large oil gallery looks great, but the oil has a difficult time flowing into the small space between the bearing and the crankshaft...and the bearing is starved for oil until the oil warms up....my opinion and I'm sticking to it.... :-)

If I recall, 60psi is where the oil pump pressure relief valve opens up, so 60psi maximum oil pressure you should see on the gauge.  Your engine won't "pop" due to high oil pressure.

The hidden oil pressure killer on these engines, is the cam bearings, or lack there of.

Only the front one is factory replaceable.
I hear you can have them bored and have ford 302 bearings installed....

I haven't put a test gauge on it, but the indicator is brand new and registers 30 to 35 psi when the engine is cold drops when the engine warms up. I think maybe the oil pump weakens when it warms up, weak regulator spring maybe. We'll see.

According to the gauge in mine, once warm at idle it show 5 psi. I run 15w40 and don't worry about it. Once I hit the gas it pops right up to 25. Same thing happens in my wagon with the same motor. 

You could verify with another gauge. Does the pressure rise with engine speed?

Larry,

I use Rotella 15-40 with a bottle of Lucas TB Zinc Plus