low oil pressure at idle
Junior Member
Joined: Oct 2008
Posts: 53
Likes: 0
From: Salisbury, maryland
Year: 1996
Model: Cherokee
Engine: 4.0
what kind of oil are they using for your oilchange? its possiple they used a standard weight oil like a sae 30 weight. the oil molecules thin out then this oil heats up where as lets say a 5w30 motor oil actually tends to thicken as the oil heats up. i ran into this problem with my hot rod at idle i had almost no oil pressure when it was hot but my iodle was set around 700 to 800 rpm. i changed to a thicker synthetic oil after the motor was broke in and my problem went away for the most part. it idles with 25psi or so witn a 10w40 now. im not saying its your problem but it sounds afully familiar.
another possibility is your oil pump may not flow enough oil at low rpms to supply the entire engine with oil. if its got alot of miles it could be a possibility. switch to a thicker oil and see if your oil pressure changes at idle.
another possibility is your oil pump may not flow enough oil at low rpms to supply the entire engine with oil. if its got alot of miles it could be a possibility. switch to a thicker oil and see if your oil pressure changes at idle.
Senior Member
Joined: Sep 2008
Posts: 772
Likes: 5
From: pa
Year: 2000
Model: Grand Cherokee
Engine: 4.0
yea,what these guys said..but to reitterate if there was too much oil put in it will cause aeration and low pressure,i've seen crazier things happen from a dealer service
Do you hear banjos?
Joined: Apr 2008
Posts: 9,644
Likes: 6
Model: Cherokee
She's tired of getting poked!!
"CF Moderator"
Joined: Sep 2008
Posts: 3,045
Likes: 3
From: N.J. Shore Area
Year: 1994
Model: Cherokee
Engine: l6 HO
You may want to check to see if the old oil filter gasket was left on then the new one put on it also. It happened to a friend of mine a wile ago and he had a similar problem with oil pressure...Tj
Renix Super Guru
Joined: Mar 2008
Posts: 24,653
Likes: 19
From: In yourz postez fissin jurr spelinzs
Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
HORNS!!!!
Newbie
Joined: Dec 2008
Posts: 5
Likes: 0
Year: 2001
Model: Grand Cherokee
Engine: 4.7
I had the same oil pressure problem at low rpm a while back. After driving for a distance of approximatly 300km and shutting the Jeep off while visiting for about a half hour, everything went back to normal.. No idea why, suspect a sticking check valve may have been the culprit.
Member
Joined: Oct 2008
Posts: 171
Likes: 0
Year: 89
Model: Cherokee
Engine: 4.0L
It is easy to damage the sender as it sets so close to the filter. Many ham fisted service guys damage hem or even breakthem completely off.
It was one of the few design flaws with the 4.0L engine IMHO.
Replace it and make double sure the wire is making a good connection, then see what your pressure reads. If it is still low replace the sender with a mechanical gauge and see what that reads at operating temp. That will be the best way to tell if you have a real problem or if it is a pseudo-problem.
It was one of the few design flaws with the 4.0L engine IMHO.
Replace it and make double sure the wire is making a good connection, then see what your pressure reads. If it is still low replace the sender with a mechanical gauge and see what that reads at operating temp. That will be the best way to tell if you have a real problem or if it is a pseudo-problem.
and yes he did something to my sending unit.. it goes 3/4 past 80 and i Doubt i have that much pressure.. lol but it runs fine w/o a light
Newbie
Joined: Apr 2011
Posts: 1
Likes: 0
Model: Cherokee
2001 XJ 168,000 miles. After engine gets warm, I put this into park & let it idle for a couple of minutes & check gauges light comes on & oil pressure goes to zero. When I drive it, the pressure goes up to about 10 lbs. I just bought this Jeep & this problem started a couple of weeks after I bought it. There was a new aftermarket sending unit on it & now it has OEM. Same problem with both. I bought this with the intent to replace the motor, just not this soon. Oh, yeah, there are no ugly noises. Thanks for any help.
Junior Member
Joined: Jul 2010
Posts: 88
Likes: 0
Model: Cherokee
Your head could have cracked a while back slowly releasing coolant into your oil. This would wear out your bearings causing your low oil pressure. At least thats what has happened to me 2000 4.0 with the 0331 head i think it is. Which is prone to cracking. Loosing any coolant?
Thread Starter
Newbie
Joined: Oct 2008
Posts: 7
Likes: 0
Year: 2001
Model: Cherokee
Engine: 4.0
@ OcalaXJ,
Mr President is the proud owner of this fine piece of machinery. Turned it in for "Cash for Clunkers". I didn't need a project. Thanks for all the replies.
Mr President is the proud owner of this fine piece of machinery. Turned it in for "Cash for Clunkers". I didn't need a project. Thanks for all the replies.
Junior Member
Joined: May 2011
Posts: 47
Likes: 0
From: Pittsburgh
Year: 1998
Model: Cherokee
Engine: 4.0L
i had the same problem in my 99. i replaced the oil pump and now when the engine is cold and at idle it makes 40 psi on the throttle its around 55psi. when the engine is warm at idle it makes 30 psi on the throttle it is around 40-50 depends how hard you get on the gas. it is boat loads better than where it was at.