Oil pressure too high? Pics inside!
Thread Starter
Senior Member
Joined: Jul 2009
Posts: 735
Likes: 1
From: Utah
Year: 1999
Model: Cherokee
Engine: I6 4.0L
Is my oil pressure too high? Or have I just never payed enough attention to the oil pressure gauge? I assume it should be more towards the middle of the gauge at only ~2200 rpm..
The first pic is at 2200 rpm. The second one is idling at 750 rpm.
Lemme know what you guys think!

The first pic is at 2200 rpm. The second one is idling at 750 rpm.
Lemme know what you guys think!

☠ CF Sheriff ☠

Joined: Nov 2009
Posts: 15,197
Likes: 18
From: Aberdeen, MD
Year: 1995
Model: Cherokee
Engine: 4.0L HO I-6, 703 Injectors, Brown Dog Super Engine Mounts
is that fully warmed up? or within the first 20 min +/- of start up?
spec is no less than 13psi at HOT idle
37-75psi above 1600rpm
hot idle is considered with the engine fully warmed up (oil takes much longer to reach operating temp than coolant)
spec is no less than 13psi at HOT idle
37-75psi above 1600rpm
hot idle is considered with the engine fully warmed up (oil takes much longer to reach operating temp than coolant)
Thread Starter
Senior Member
Joined: Jul 2009
Posts: 735
Likes: 1
From: Utah
Year: 1999
Model: Cherokee
Engine: I6 4.0L
I had been driving about 20 minutes.. So that would be normal pressure?
I was changing my oil the other night (after downing a few drinks) and forgot to change the filter. I figured the filter only held .5 quarts so I just added 5.5 quarts and decided I would do an early oil change next time since I missed the filter. I'm hoping I didnt over fill it and cause any issues haha.
I was changing my oil the other night (after downing a few drinks) and forgot to change the filter. I figured the filter only held .5 quarts so I just added 5.5 quarts and decided I would do an early oil change next time since I missed the filter. I'm hoping I didnt over fill it and cause any issues haha.
☠ CF Sheriff ☠

Joined: Nov 2009
Posts: 15,197
Likes: 18
From: Aberdeen, MD
Year: 1995
Model: Cherokee
Engine: 4.0L HO I-6, 703 Injectors, Brown Dog Super Engine Mounts
I had been driving about 20 minutes.. So that would be normal pressure?
I was changing my oil the other night (after downing a few drinks) and forgot to change the filter. I figured the filter only held .5 quarts so I just added 5.5 quarts and decided I would do an early oil change next time since I missed the filter. I'm hoping I didnt over fill it and cause any issues haha.
I was changing my oil the other night (after downing a few drinks) and forgot to change the filter. I figured the filter only held .5 quarts so I just added 5.5 quarts and decided I would do an early oil change next time since I missed the filter. I'm hoping I didnt over fill it and cause any issues haha.
and you can change the filter without draining the oil - i would highly recommend doing so, the oil lasts much longer than a filter will. Some people change the filter every 5000 miles, but run the oil to 10000+ (verified ok by used oil anaylsis)
watch it on a longer trip and see if it goes back down to normal. What weight oil are you using?
CF Veteran




Joined: Nov 2010
Posts: 5,841
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
I think your oil pressure sending unit is failing. It is a VERY common failure on the 4.0 engine. When the fail, they fail with "higher" readings more often than lower readings, although it can go both ways.
I recommend purchasing these directly from Jeep. Well worth the extra $20 for the best reliability/accuracy/mating with your factory gauge.
I recommend purchasing these directly from Jeep. Well worth the extra $20 for the best reliability/accuracy/mating with your factory gauge.
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I think your oil pressure sending unit is failing. It is a VERY common failure on the 4.0 engine. When the fail, they fail with "higher" readings more often than lower readings, although it can go both ways.
I recommend purchasing these directly from Jeep. Well worth the extra $20 for the best reliability/accuracy/mating with your factory gauge.
I recommend purchasing these directly from Jeep. Well worth the extra $20 for the best reliability/accuracy/mating with your factory gauge.
CF Veteran
Joined: Jan 2011
Posts: 1,894
Likes: 4
From: Las Vegas
Year: 1999
Model: Cherokee
Engine: 4.0
well it's easy enough to check if you did or not lol
and you can change the filter without draining the oil - i would highly recommend doing so, the oil lasts much longer than a filter will. Some people change the filter every 5000 miles, but run the oil to 10000+ (verified ok by used oil anaylsis)
watch it on a longer trip and see if it goes back down to normal. What weight oil are you using?
and you can change the filter without draining the oil - i would highly recommend doing so, the oil lasts much longer than a filter will. Some people change the filter every 5000 miles, but run the oil to 10000+ (verified ok by used oil anaylsis)
watch it on a longer trip and see if it goes back down to normal. What weight oil are you using?
☠ CF Sheriff ☠

Joined: Nov 2009
Posts: 15,197
Likes: 18
From: Aberdeen, MD
Year: 1995
Model: Cherokee
Engine: 4.0L HO I-6, 703 Injectors, Brown Dog Super Engine Mounts
maybe 1/2 quart - prime the filter and install, run a few minutes, shut off, then check the level after it settles
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