Low oil pressure on startup, reason for concern?
Senior Member
Joined: Jan 2011
Posts: 957
Likes: 2
From: Russellville, Arkansas
Year: 1991
Model: Cherokee
Engine: 4.0 I-6
I had a problem like this, a "dry start." The anti-drain back valve in my filter was shot (Napa Gold). I changed the filter (and the oil cause it needed it anyway) and my problem was solved. My oil pressure rises almost instantly as soon as the motor starts now where as it used to take 6-7 seconds and you could here a lot of noise from the engine. Now, it's about as smooth as an XJ with a 4.0 can be.
Senior Member
Joined: Jan 2012
Posts: 952
Likes: 4
Year: 2004
Model: Grand Cherokee
Engine: 2000 4.0
what weight oil and what are the ambient temperatures when you first start it? Does it do this from a warm start? Does your gage move this slow when you do the "check gage test?
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Am I looking at the right video? That doesn't look that slow to come up in my opinion. I've never seen the oil pressure indication in my '99 race up to 50 psi, even with a new sensor installed.
Don't forget the oil pressure sensor has a damper feature in that the oil pressure acts upon a diaphagm and not a bourdon tube (which can react quicker). The dampened indication can be somewhat slow to react. Plus to that (a hillbilly told be that once - LOL) an accurate instrument readout depends on a near perfect electrical circuit involving the PCM, CCD Data Bus, and instrument cluster.
To test the OP needle sweep do this test:
Instrument Cluster Actuator Test
(1) Begin the test with the ignition switch in the Off position.
(2) Depress the trip odometer reset button.
(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On position, but do not start the engine.
(4) Release the trip odometer reset button.
(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.
(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.
Don't forget the oil pressure sensor has a damper feature in that the oil pressure acts upon a diaphagm and not a bourdon tube (which can react quicker). The dampened indication can be somewhat slow to react. Plus to that (a hillbilly told be that once - LOL) an accurate instrument readout depends on a near perfect electrical circuit involving the PCM, CCD Data Bus, and instrument cluster.
To test the OP needle sweep do this test:
Instrument Cluster Actuator Test
(1) Begin the test with the ignition switch in the Off position.
(2) Depress the trip odometer reset button.
(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On position, but do not start the engine.
(4) Release the trip odometer reset button.
(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.
(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.
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Thread Starter
CF Veteran
Joined: Jul 2012
Posts: 3,142
Likes: 361
From: Andover, VT
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 L
10w-30, temp outside was cold (25-30*F) but engine was semi-warm. It does this whether its cold or hot, but more exaggerated when cold. I'm not sure what you mean by check gauge test, can you elaborate?
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Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
See post #7. And what brand of oil filter are you currently using?
Thread Starter
CF Veteran
Joined: Jul 2012
Posts: 3,142
Likes: 361
From: Andover, VT
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 L
Napa filter, oil done about 4k miles ago so about time to get some new stuff in there. Any recommendation on a filter? I've heard the napa golds are good, along with wix, and to stay away from fram and other garbage.
Thread Starter
CF Veteran
Joined: Jul 2012
Posts: 3,142
Likes: 361
From: Andover, VT
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 L
Am I looking at the right video? That doesn't look that slow to come up in my opinion. I've never seen the oil pressure indication in my '99 race up to 50 psi, even with a new sensor installed.
Don't forget the oil pressure sensor has a damper feature in that the oil pressure acts upon a diaphagm and not a bourdon tube (which can react quicker). The dampened indication can be somewhat slow to react. Plus to that (a hillbilly told be that once - LOL) an accurate instrument readout depends on a near perfect electrical circuit involving the PCM, CCD Data Bus, and instrument cluster.
To test the OP needle sweep do this test:
Instrument Cluster Actuator Test
(1) Begin the test with the ignition switch in the Off position.
(2) Depress the trip odometer reset button.
(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On position, but do not start the engine.
(4) Release the trip odometer reset button.
(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.
(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.
Don't forget the oil pressure sensor has a damper feature in that the oil pressure acts upon a diaphagm and not a bourdon tube (which can react quicker). The dampened indication can be somewhat slow to react. Plus to that (a hillbilly told be that once - LOL) an accurate instrument readout depends on a near perfect electrical circuit involving the PCM, CCD Data Bus, and instrument cluster.
To test the OP needle sweep do this test:
Instrument Cluster Actuator Test
(1) Begin the test with the ignition switch in the Off position.
(2) Depress the trip odometer reset button.
(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On position, but do not start the engine.
(4) Release the trip odometer reset button.
(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.
(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Your current filter selection is fine. Even the Napa Silver line is good if you're changing your oil every 4K or so.
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
It proves that your oil pressure indication is working properly (PCM/CCD Data Bus - wise). In this case, any defect in the OP indication system would be upstream of the PCM (Sensor/Wiring/Engine oil system).
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