Low Oil pressure after rebuild - NEED Your Wisdom!

7 weeks ago I took my truck (07 KW T600 with CAT C15 Acert) to a reputable shop near me to have the engine inframed.

The last 2 weeks they have been trying to figure out why it's having oil pressure problems.

This engine has never, in the 5 or 6 years I've owned it, had oil pressure problems. And had good pressures when I dropped it off. I was having cooling issues. But nothing to do with oil. Turned out the engine had a cracked liner. So, the inframe was indeed needed.

So, after new liners, pistons, head, etc, the truck idles 10psi lower than the 22-25 it did prior. And won't get over 45 psi at 1300 rpm. They pulled the pan and 2 different people checked the bearing clearances. Which are good.

It was decided that the oil pump was failing. New oil pump. No change. Then they started hooking up mechanical gauges anywhere they could and noticed before the oil filter they got 80 psi. Immediately after the filter they got 40 or less. So, add in a new oil filter housing. Pressures came up. And all was well in the world.

UNTIL ... they took it for a test drive and the OIL pressure light came on.

That was just a little while ago.

They are scratching their heads. Meanwhile, my bank accounts are dropping like rocks having been off for 7 weeks.

If you have any ideas on what these guys can look at that might cause this problem, please let me know. I'll forward it along. Personally, I think one of the new parts in the rebuild was faulty. Which one? I have no idea.

 

One

What spec are you asking for? Uncertain. but I'll live dangerously and assume your talking oil pressure specs. Minimum (from a CAT graph I found on line) is 15 psi @ 600 rpm and 42 (ish) @ 1200 and up.

 

I'll send that on to them. I know I said "near me", but where I am you can't find any good rebuilders inside 1.5 hours away.

 

I have no idea either way.

 

Thanks fellas. The cam wasn't removed as they said it looked really good when they inspected it. Could they have done something to it? I'm not sure if they messed around in that area or not.

I'm not an "internal" engine mechanic. I'll change anything on the outside though. But, y'all probably figured that out already. I'm just trying to give them a list in the hopes it'll get them thinking about whatever the problem is. Like I said, the bank accounts are getting smaller. And the McD's here isn't hiring right now.