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Discussion Starter · #1 ·
My oil pressure warning light comes on. The gauge stays at around 40 lbs. The only time the light comes on is when I am getting off the highway after driving for a little bit. It doesn't do it when I drive around town or short distances. The light goes out if I give it the lightest throttle. Any suggestions? How hard is it to change an oil pump?
 

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that would be bad new bears. not fun. that means lifting hte motor out a little, taking the pan off, and replacing the pump. not something you are going to want to do
 

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AlGores worst nightmare
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Change the sending unit first.
Fairly common Cummins/Dodge gremlin.
And/or add a mechanical gauge.
 

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Discussion Starter · #4 · (Edited)
I am putting in a mechanical gauge tomorrow I hope it will fix it, cause I am driving to florida on sunday, after lima 4x4 show. What is weird is that it only acts up after long highway driving, when I slow down
 

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I just saw that you posted this question in two places. I am only going to reply here.

On my 96 the gauge started fluctuating wildly but the O/P lamp never came on. I temporarily put a mechanical O/P gauge on it and confirmed I had good O/P. I replaced the sending unit and the gauge started working normally again.

You have a good plan with the mechanical gauge. You need to make sure you have good oil pressure.

When you pull off the freeway is probably the time the oil is hottest and thus the thinnest. If the oil is above full on the dipstick you may have fuel in the oil which thins it, too.

The oil pump is inside the front timing cover (The pan does not have to come off.) If you have not tabbed the KDP you could look at the pump while you have the cover off to tab it.

I put an oil pump related question in this forum but never got an answer.
http://www.cumminsforum.com/forum/94-98-powertrain/62269-oil-pump.html
 

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mine did the same until i replaced the sending unit. everyone I have talked to said the stock oil pump is hard to kill, it might get tired after 1,000,000 miles.
 

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I'd check the idle speed. Pretty common on these trucks to lose oil pressure if the idle in too slow.
 

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Discussion Starter · #8 ·
Mechanical gauge in. Idle is about 700 rpm. Pressure at idle 20lbs, at highway speed 60lbs, and when I get off the highway about 18lbs when the light comes on. The factory gauge barely changes off of 40lbs. One friend suggested main bearings are worn. How difficult are they to replace? Any other suggestions?
 

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AlGores worst nightmare
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By "when I get off the highway" do you mean when you stop at the bottom of the ramp? Thats not bad oil pressure, just 2 lbs lower than normal idle.
What oil are you using?
 

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Discussion Starter · #10 ·
when I stop, or at idle for a least a minute after being on the highway.
 

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AlGores worst nightmare
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What oil are you using? That pressure isn't bad.
You could have an oil analysis done.
Really these motors are hard to hurt, and generally last a long time. I'd change the sensor, Cummins part# 3923200, and see if that stops the light coming on.
 

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I had the exact problem, my idle was to low. I was told there is a known computer issue that may need to be reflashed.
 

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I think its the sender with a sudden stop the sender doesn't respond fast enough.
 
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