TJ 4.0 low oil pressure

[RedHeep]

Friend of mine has a TJ, recent purchase, typical 4.0 oil pressure issues.

It's at 5 psi warm at idle. Already switched to 20w50. Ticks a lot on the top end. Anybody think this can be an oil pump issue and not bearings?

It also has coolant loss, but there's no leaks visible and no noticeable white smoke. My initial thought was head gasket, like the PO might have overheated it, but the oil is clean and the coolant looks normal.

It's a 4.0, so it should be easy to diagnose, but I'm stumped. Anybody got any thoughts? I'd rather not tear it apart just for the sake of tearing it apart.

 

[muduck18]

check your compression?

The coolant leak could be not enough to show too much smoke, or it could be leaking on the outside of the engine and evaporating before it drips. (weep hole in water pump?)

other than that, would have to see/hear/touch to know...
good luck..

 

[CherBear]

Let me guess, is it a 99-01 TJ?

 

[RedHeep]

Not sure the year, I'll ask.

He told me that he's putting 2 gallons of coolant in it every 2 weeks. It has to be something leaking somewhere.

Edit: It's an '01

 

[RedHeep]

I don't know why the 0331 head didn't hit me before. I'm sure that's what it is.

I found one at the local yard from an '02 Grand for $200, so hopefully we'll get it fixed.

 

[muduck18]

I don't know why the 0331 head didn't hit me before. I'm sure that's what it is.

I found one at the local yard from an '02 Grand for $200, so hopefully we'll get it fixed.

thats it boi..

you should swap a 0330 and headers onto it :-D

 

[RedHeep]

thats it boi..

you should swap a 0330 and headers onto it :-D

Guys not a wheeler (yet). He'll be happy that his bottom end isn't toast and we can fix it on a saturday.

 

[CherBear]

When in doubt, 0331 it out...

 

[Jed]

I've been thinking of upgrading my old rig looking at 99-ish model xj's. I wasn't aware of this head issue... I can see changing the head to cure the coolant problem but this isn't going to solve the low oil pressure problem.... is it??

 

[RedHeep]

Head wasn't cracked. I think the low oil pressure is the bearings. Don't know where the coolant is going.

He's headed to Japan in the summer, so he just wants to put a replacement engine in it and be done with it.

 

[Jed]

I've always heard worn cam bearings is what makes the oil pressure drop in the 4.0's.

A friend of mine changed his rod and main bearings and it didn't help his oil pressure. Later he put in a high volume oil pump and that helped.

 

[joe_peters]

Have you confirmed the low oil pressure with a mechanical gauge, or are you going off of the instrument panel gauge?

 

[RedHeep]

Have you confirmed the low oil pressure with a mechanical gauge, or are you going off of the instrument panel gauge?

Spare me the newbie questions will ya?

As far as I know, he's decided to replace the short block and move on.

 

[RichP]

If he wants to go whole hog price out a factory MOPAR stroker, crate motor drop in, they have it for the 4.0, takes it out to a 4.7 with factory warranty. If I could find a newer 99 - 02 TJ or unlimited with a blown engine that's the route I would go.