Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2000 jeep grand Cherokee low oil pressure... HELP!

Ok folks here it is… recently I posted about my 2000 jeep grand Cherokee low oil pressure. I’ve done everything I could think of from the rod bearings to the main bearings… I did the rear main seal the sending unit. With one of the rod caps moving pretty good I even put in a over sizes bearing to tighten it up and it did but I’m still getting low oil pressure. Nothing seems to be working. Besides dropping a new engine in it that I dont have to money for btw. Is there anyone out there with some kind of miracle trick… did I miss something. Im fried.

It’s almost a certainty that your work on the bottom end was a waste. If a rod big end was loose enough that you could rattle it the engine needed to be pulled and rebuilt. Along with a worn crankshaft that would quickly damage the new inserts you must consider the camshaft bearings.

BTW which engine is it and how many miles are on it?

Agreed with Rod_Knox.

The best thing to have done (water under the bridge now…) would have been to use a micrometer and check the crank journals for wear.
Just because the rod caps are not moving does not mean the journals are not badly worn.

The use of Plastigage may have helped determine this; unless the clearances are so large the Plastigage wouldn’t squash down…


I seem to remember the previous discussion

4 liter in-line 6 cylinder

It’s a 4.0L inline 6 cylinder with 166005.i figured I could somehow save it until I could get the money to drop a new one in. It drives fine outside of the low oil pressure dropping 5 or 10 but I don’t want to have that problem.

It’s a shame that you did all that work and find it didn’t correct the problem. I’m surprised that you could get the pan down and replace those bearings. At this point about all you can do is use heavier oil such as 10W40 and drive sedately until something lets go.

I have owned several Cherokees with the 4.0 engine and they all went to the junk yard due to transmission failure or collision. None of the engines ever failed although all of them developed a thirst for oil needing a quart or two between changes.

Have you changed the oil pump relief valve spring?

Drops under what conditions ?
What is the pressure at idle when cold? When warm ? at highway speeds?
Does your “Check Gauges” light come on?

No. That’s the only thing i havn’t done so far. Do you think its wortb a shot?

At idel it’s 40 or better… when the envine is warm it drops to 5 may be lower. When im driving it goes back to 40. The gauge light comes on at idel… sometimes.

Sure, at least you’ll find out if it really is the only thing you haven’t done…


I did change the oil pump and pick up tube if thats where the spring is.

I changes out the whole oil pump and pick up tube

I think the relief valve is in the pump, but can’t confirm it. Have you tried 10W-40 oil?