Hey guys,

I am having an issue with my oil pressure dropping. I just replaced the pan, rear main seal and pump almost two weeks ago, it's been fine holding pressure till today when I did a little trailing then when I got on the highway the pressure was dropping to almost idling and it kept fluctuating until I parked it for a few hours then drive it again and it's fine but then I was doing some city driving and it was fluctuating again. Oil level is fine, not sure what's going on! Any ideas would be appreciated, thanks!

 

I believe the oil gauge is notorious for being wrong, find another way to get a quality gauge reading. or replace the sending unit and hope that does it. its not an 2001 is it? nevermind i just saw in youre first post its a 98 at least you dont have the cracked head issue to worry about

 

Yeah should have specified year. That's what everyone is saying to replace the sender! Think an aftermarket oil pressure gauge will fix the issue as well?

 

you mentioned you work at a dealership, i would think one of the techs would have a gauge they could put on it to confirm the actual pressure

http://www.rockauto.com/catalog/raframecatalog.php

1998 JEEP CHEROKEE 4.0L L6 : Electrical-Switch & Relay : Oil Pressure Sender / Switch Price
STANDARD MOTOR PRODUCTS Part # PS291T T-Series
w/ Gauge

$19.30

AIRTEX Part # 9M9 AdvanTech (Economy Line)
WITH GAUGE
$22.79

AIRTEX Part # 1S6723 {Click Info Link for Alternate/OEM Part Numbers}
WITH GAUGE

$24.89

STANDARD MOTOR PRODUCTS Part # PS291 {#5003675AA, 56031005} Thread Size - NPT: 1/8" - 27 Thread; Pin Terminals; Terminal Gender: Male; Direct OE Replacement; Number of Terminals: 2; Connector Gender: Female
w/ Gauge; With Gauge

 

Good advice given already about VERIFYING the actual oil pressure.

Have to ask though. What oil filter are you using?

 

Question: 1. Why did you replace oil pump?
2. Did you install a new pickup and press fit it correctly
3. Did you torque the pump mounting bolts
4. what are pressures and rpm's

 

Excellent questions .

 

I replaced the oil pan because it was leaking I think could really verify where the oil was coming from but the pan was pretty beat up and it looked as if it were taken off before and instead of replacing the old gasket with a new one they just put silicon around the pan. So when I replaced that I decided to replace the pump as well and it came with a pickup. The work was done almost two weeks ago and I have a Fram oil filter. I had the guys at my work do the work because I work at a Jaguar/Land Rover dealership.

 

If it continues which it still is tomorrow or Friday im going to put one if those oil pressure readers on and drive around to check how much pressure there is. Some are saying the sender might be bad, the gauge itself, wiring or the pump is bad but there is pressure though but not where I'd like it to be!

 

First thing most people will tell you is to ditch the fram because they're junk. Try a wix filter and see if that helps.

 

Where did you get a pump with a pckup already installed? I just bought a pump from the dealer that the pickup tube come seperate from the pump. Most pumps on the market come without a pickup tube installed.

Did you preoil the pump before install, and did you preoil the engine after all that work was performed?

 

You beat me Quick Draw.

OP, never use Fram filters on your 4.0. Too high a failure rate and a **** poor anti drainback valve. Wix, Napa, or Mopar are all easy to find and reasonably priced.

 

The pump and pickup came in one box got that from autozone! After the work was done we ran the oil we use in the Jags and Rovers for a few minutes then replaced that with full synthetic high mileage.....forget what synthetic oil I used though.

 

I got the oil and filter in a package deal buy one of those 5 or 6 qt bottles and get a Fram filter. I'm definitely going to get a different filter now! Thanks for letting me know!

 

I run rotella 15w40 in mine.