• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Oil pressure is backwards

ktilcu

ktilcu

NAXJA Forum User
Location
Largo, Fl
I know there have been a lot of threads about oil pressure and the sending unit but i have one for ya. My oil pressure is very low (0) but only when i am sitting still or pushing on the gas. When i am coasting the pressure goes up (25). Push on the gas it goes back to 0. Changed the sending unit, just had an oil change. So I'm at a loss here. What do you guys think? Oil pump? No real leaks although i did see bubbles coming out of the oil filter adapter... Any help is appreciated.
 
94 4.0 HO and i got it from the stealership so i hope it's not wrong... looks exactly the same...
 
Last edited:
did they give you a pressure sender or pressure switch?
The pressure sender is a variable resistor, the pressure switch is for the idiot light and it's an on/off kind of deal.
What P/N did they give you?
 
yeah positive i got the sender... just ran and checked... also the engine starts to sound like it has no oil when the pressure goes to zero... so i'm thinking the pressure is actually at zero. That the sender is right. What could be doing that?
 
Last edited:
If it starts to sound like it's getting no oil when you step on the skinny pedal and the pressure drops to zero, stop driving it untill you can get it fixed.....since it sounds like you obviously have a problem, that's not a sending unit issue.

How many miles are on your Jeep? I have to wonder if the Oil pump is on its way out....
 
107xxx ish... and just to cover i did check the actual oil and it's a little too full ... since the pump pulls more oil when you accelerate could it be picking up sludge in the pan whenever i give it gas and then when i let it coast it drops the sludge back in the pan? Or maybe the same thing in the filter... it happens the same way everytime. When i changed my valve cover about a year ago there was gook everywhere i had about 1/2 qt of the stuf just on the cover... smae thing in the pan maybe clogging a screen (if there is one down there?):huh:
 
If it were me, and you're not gonna like this, I would drain the oil and drop the pan and see whats going on in there. See if there is any crap in the pump, or on the bottom of the pan. And while you have the pan off, i'd throw a new pump on there. Even if that doesn't solve the problem, atleast you'd have the peace of mind knowing that you have a new pump in there.
 
the while your in there's are what i don't like because my rear main is leaking so while i'm in there...:smsoap: I'm sure you guys know how it goes... and the front will probably need it and the oil adapter... once you start there is no stopping... while your in there.
 
This may sound like a stupid question, but are you sure you have enough oil in the motor? When you step on the gas, the oil pump picks up oil from the pan, dropping the level of "reserve" oil in the pan. At idle, it doesn't pull as hard, meaning the oil level in the pan is higher. That could accound for your zero reading at high RPMs and better readings at idle. But that's a pretty unlikely scenario.

What is more likely, though, is some sort of problem with your oil gauge, your sender, or the wiring in between them. You should hook up a mechanical oil pressure gauge to verify that your pressure is really at zero. Once you can be sure of your pressure situation, you can then try to find out what the problem is.
 
Last edited:
I would think it is probably a problem with the suction screen/pickup tube. They do have a suction screen and they can get clogged. From what you said earlier about all the sludge I would bet the screen is loading up with trash. :shocked:

Also might be a bad, or plugged up oil filter. What brand is the oil filter?

Definately time to drop the oil pan while you still have an engine, if it is not already too late!:shiver:
 
alright I had to take it to the mechanics just cause it needed to get done. He took the oil pan off and said that it was almost full of sludge and carbon. Apparently the people who had it before me decided they didn't want to change the oil or something. He said the screen wasn't cleanable and he has to send the pan to the machine shop to get it clean. Pics later... Also the rear main was leaking enough to run through 5qts of clean oil (last oil change) to less than 1qt in 6 weeks. But instead of leaking on the ground it was all over the bottom of my truck... the reason the dipstick didn't show low oil is the sludge displaced what was was left, giving a false reading...
 
My gawd....I definitely wanna see pics of this thing now!

With such low miles on a 94, I have to wonder if it suffered from extreme short distance driving, in addition to lack of oil changes.
 
I would imagine. Since i had it i've changed the oil and filter every two months. I also drive over 200 highway miles a week. So whoever had it before me was horrible with maintainence.
 
pic.php
pic.php

This is the buildup in the pan, the pump, the screen
http://www.putfile.com/pic.php?img=4775185
http://www.putfile.com/pic.php?img=4775185
http://www.putfile.com/pic.php?img=4775185
 

this is my oil pan contents


This is the pump



This is the screen ... figured out the picture thing!
pic.php
 
wow im just glad mine doesnt look like that and you are getting yours fixed so it won't look like that anymore
 
You must log in or register to reply here.

Similar threads

M
Oil pressure question
2
Replies
26
Views
3K
Money_Pit_Incoming
M
J
AW4 Problem shifting first to second when hot
Replies
2
Views
1K
cruiser54
C
H
Oil pressure sender 98 vs 99
Replies
14
Views
2K
hbar..
H
N
New Engine is Hard to Start
Replies
0
Views
34
NGThomas
N
Jeepmedic46
Low oil pressure
Replies
13
Views
1K
denverd1
denverd1
Back
Top