Oil pressure low?

JULES94

MEMBER
2002 JEEP GRAND CHEROKEE
4.0L
6 CYL
4WD
AUTOMATIC
325,000 MILES

My oil pressure drops when I stop raises a bit when I accelerate but never makes it past the quarter marker on the gage. Just recently changed the oil pressure sending unit cause my oil pressure was too high which fixed it now its running too low some tips or help please.

7 Replies

CARADIODOC

MECHANIC
33,942 POSTS

Check the actual pressure checked with a mechanical gauge, then if it is really too low, it is likely due to worn crankshaft bearings at the mileage you listed. They can be replaced before serious damage occurs to the crankshaft journals. This guide can help us see whats going on.

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

Please run down this guide and report back.

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Tuesday, June 16th, 2015 AT 1:01 AM

SHAWNA LEE ORBAN

MEMBER
2 POSTS
2000 JEEP GRAND CHEROKEE
4.7L
V8
4WD
AUTOMATIC
120,000 MILES

Hello, I drive the vehicle listed above Limited model (yes it is a hard life). My oil pressure gauge is dropping down to 0 PSI when my car is idling but when I start driving (over 30 MPH) it goes up to 40 PSI (slowly). When I'm driving around town (under 30 MPH) it fluctuates up just a little from 0 PSI and back to 0 PSI constantly and whenever I stop it drops back to 0 PSI. I just changed the oil in it 300 miles ago I put 5w-30 in it because I live where its usually sub zero. The motor is not making any unusual noises it idles, runs and shifts smoothly, no stalling or sputtering. Also there is no check engine light just a check gauges light that pops on and off and dings constantly. (I married a man who is too stupid to even change the belt on the vacuum cleaner please help)

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Thursday, November 26th, 2020 AT 11:05 AM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,911 POSTS

Hi and thanks for using 2CarPros.

If there is no ticking or knocking from the engine when the gauge says 0 psi, chances are the oil pressure switch it bad. Often times, the crimp where they are put together comes loose and then oil will bypass it causing an oil leak and a low pressure reading.

With that in mind, I recommend checking it first. It is located just above the oil filter. Here are the directions for replacing one.

PROCEDURES
REMOVAL
1. Disconnect the negative cable from the battery.
2. Raise vehicle on hoist.
3. Remove front splash shield.

Picture 1

Figure 116

4. Disconnect oil pressure sender wire (Fig. 116).
5. Remove the pressure sender (Fig. 116).

INSTALLATION
1. Install oil pressure sender.
2. Connect oil pressure sender wire.
3. Install front splash shield.
4. Lower vehicle.
5. Connect the negative battery cable.

Let me know what you find.

Take care,
Joe

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Thursday, November 26th, 2020 AT 11:05 AM (Merged)

SHAWNA LEE ORBAN

MEMBER
2 POSTS

Thank you very much! I will start there and see what happens.

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Thursday, November 26th, 2020 AT 11:05 AM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,911 POSTS

Happy to help. Let me know what you find. Also, disconnect the electrical connector and make sure there is no corrosion or other issues. If this doesn't prove to be the problem, go to the local parts store and rent a mechanical oil pressure gauge for testing. Basically, you remove the electrical switch and screw in the mechanical. When you start the engine, you will see the actual oil pressure being produced. This way you can confirm it isn't an internal engine issue.

Let me know if I can help.

Take care,
Joe