Jeeps and oil pressure..

    Since many have commented about low oil pressure at idle in Jeeps, I thought I would post this...



    I have had the low oil pressure @ idle issue in my scrambler for years. Even cold and reved up , would not hit over 40psi.


    Since then i have replaced my gauge. and the issue remained.


    Now I just replaced my rear main seal and popped in a new high volume oil pump. All went great.. so far, no leaks!


    Now the oil pressure at start up is 50 psi at idle and hits 65 at rev!
    then as the Jeep warms up the numbers drop...
    Warm idle is now at about 5-10psi, and quickly goes up to 40-50 at 2000 rpm


    far better than the old oil pump but still drops lower than would seem ok at warm idle.


    Steve

    Nobody belongs anywhere, nobody exists on purpose, everybody's going to die. Have a beer.


    Jeeps Owned... 89YJ, 81CJ-8, 99XJ, 93XJ, 00WJ, 05LJ, 22Bronco Badlands !

    My street jeep basically reads zero at idle. Most higher milage 4.0l run a half pound per 100 rpm. Not sure it is right but it is very common and does not seem to hurt the motor.


    Aaron

    When my new 4.0 motor was built they expanded the oiling system by drilling the head and block, at idle it's about 20 psi any higher it's about 40-50 constantly.


    My old 2.5 would be 5 psi at idle and about 25 psi when the squarrels were running as fast as it could, seams to be common and I was told running an desiel oil is better for jeep 4.0's, but have yet to hear or see anyone doing so.


    Cj-

    [quote author=deadfeat link=topic=35530.msg288620#msg288620 date=1340990394
    Doesw prove that a new HV oil pump makes a difference.



    [/quote]



    i know you have a 258, but most high volume pumps wont fit under the 4.0l pan. i could not get one in the motor i pulled from a 91 xj.


    aaron

    Quote from astape


    [quote author=deadfeat link=topic=35530.msg288620#msg288620 date=1340990394
    Doesw prove that a new HV oil pump makes a difference.



    i know you have a 258, but most high volume pumps wont fit under the 4.0l pan. i could not get one in the motor i pulled from a 91 xj.


    aaron



    Aaron, you are right, I checked, and the pump I have "Meets or Exceeds" OEM , but is not high volume.. That said it was a little beefier than the original I removed.

    Nobody belongs anywhere, nobody exists on purpose, everybody's going to die. Have a beer.


    Jeeps Owned... 89YJ, 81CJ-8, 99XJ, 93XJ, 00WJ, 05LJ, 22Bronco Badlands !

    My old 4.2 was similar . No preasure at idle around 10 psi. also had about 172,000 miles on it. When I rebullt motor new H.V. pump new bearings and seals. Pressure went up to 45 psi. at idle at higher rpms. around 65 psi. new sender and connections on sender. Motor bored out .040 over, stroked and blue printed with H.O. 4.0 head. runs very strong . after 6,000 + miles no issuse or problems with oil pressure.

    my 83 CJ would have almost nothing at idle, and only go to about 10 when driving.....i put close to 30K miles on it and never had an issue

    On the CJ motor a common problem is for the sending unit to go bad they also have a tendancy to clog the little opening were it screws in with sludge . When running down the road you might see 40Lbs then it will drop off to nothing or close to it at idle.

Participate now!

Don’t have an account yet? Register yourself now and be a part of our community!

Register Yourself Login