I have only had my jeep about a month now and noticed shortly after buying it that once the engine got warm that my oil pressure would drop to about 9-10 psi while at idle. While driving I was fine my pressure would sit at about 40-45psi. So I came to this forum and a couple others in search of a cure or at least some help.

After reading through countless threads on all these different forums I was sure my bearings were shot and I needed a rebuild. I tried changing the oil with a heavier weight oil, switched to a Napa filter, and still had the same issue. I was about to change my oil pump out, But today I decided to try one last thing. I went to the dealership and spent the $60 on an OEM Oil pressure switch. I changed it out and guess what? Now at warm idle my pressure sits at 30 psi and while driving 50-60 psi.

I know the oil switch is one of the things many people suggest but let me make it clear that you really need to get an OEM switch, I bought one from Napa first and it was DOA. Spend the extra $20 and get a quality part.

 

Glad it was a simple fix!

 

Did you confirm it had low pressure with a manual gauge?

 

No. None of the local parts places had a manual gauge I could barrow so I just bit the bullet and bought the switch.

My main reason for posting this was that sometimes these forums remind me of "WebMD". You go on that site and type in that you have a runny nose and by the time you get done reading you are sure you have cancer. I figured it might be nice for others to read that its not always the worst possible outcome.

 

What are you talking about??? :O Your profile says 1998, which must mean it was built in 98 which makes it a 99 model year and I read somewhere on Yahoo Answers (best site ever btw, it's where I read how babby is formed) that some 99's have the 0331 so you must have a cracked head oh man running for a month like that? Sorry time for a new engine bro.

Glad to hear you kept your head and followed a rational path

 

And replace the CPS.

 

I might have to do this same thing. What you described is exactly what mine does too.

 

Run Seafoam through your CPS first

 

i heard that if run 0w-20 in a 4.0 the oil pressure is much more stable.................

 

I prefer a negative viscosity oil like -10/30. It flows so well it actually spins the oil pump for you with it's own momentum at low RPM, keeping oil pressure constant. If you experience unintended acceleration, add 1 qt Lucas. Or install an oil brake.

 

Glad I'm not the only one who has noticed the death and destruction attitude people have on these forums, lol. Thanks for the laugh guys. Oh and I'm on my way to get some negative viscosity full synthetic oil now.

 

Hahaha "Oil Brake". What about a variable vane oil pump, that makes it like a turbo, right?

 

It must be true if it's on the internet. By the way, I'm a french model, bonjour!

 

I prefer oil of olay with its anti-aging properties.... the old 4.0 will last forever.