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Oil pressure sending unit going bad?

6617 Views 13 Replies 8 Participants Last post by  illflem
Hey fellas, my oil pressure gauge has been acting funny lately. Sits right around 40psi at idle but when I accelerate it will drop to the bottom of the operating zone and sometimes below that. Never goes to 0psi. Also once up to speed and just cruising it will fluctuate from bottom of the operating zone to 40. Sometimes it does fluctuates and sometimes it's sits steady at 40psi whole cruising. Has dropped below the normal zone a few times but never to zero.

Oil level is good. And I moved my fuel pressure gauge over to the the top of the oil filter housing to check with psi with gauge. Never sees less than 55psi when cruising at around 1850-2000 rpms. Even while the factory oil pressure gauge is fluctuating. Also while accelerating, when the factory gauge is dropping, my other gauge is increasing up to 57 psi.

Also I thought the factory gauge in our truck was an actual gauge reading unlike some new trucks

Does this sound like the sending unit is starting to go bad? Thanks for any input
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I'd say it's def the sending unit , mine does the same thing since I got it two yrs ago . I also checked mine with a manual gage and all was good so I haven't really worried about it since then.

Sent from App
Did a sending unit fix this? Wondering because I'm experiencing similar issues.
get the sending unit from cummins too guys I used a cheap one from advance and it wasn't much better than the one I had crapping out. even though the cummins one is 4 times higher
Good deal.
Clean the connector first before replacing the sender.
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mine doing the same thing with one coming from NAPA still the same thing i check it with a manual gauge and it says 30 ideling
Both good pieces of advice. What my '97 w/ 300k miles is doing, when you start it up the oil light comes on for a 2-3 seconds, along with the gauge around zero. The light goes out and the gauge immediately goes up and registers. I'm hoping it just a corrosion/sender issue.
its takes a cummins little bit to build oil psi my truck when i first start it the sending unit works but i think the range is not right on a cheep ol but it takes 5 to 7 seconds for mine to build ( and it takes long bc i hold the throttle down 1/4 when start so it fires up on the first rotation )
The first five seconds after the engine starts the dash and computer go though a self check.
None of the gauges read correctly till all the warning lights go off.
The first five seconds after the engine starts the dash and computer go though a self check.
None of the gauges read correctly till all the warning lights go off.
Well if that's the case, my truck is behaving normally. That's good to know. I bought this truck used. It's also the first goat I've owned since a late '70s model.
I had the same problem on my v10 and replaced the sending unit . It still did the same thing so I installed a tee at the sending unit and now use a mechanical gauge along with the dash gauge. I worried about it for a couple years and now there is no question.My dash gauge still goes up and down but has not turn on the CEL yet.
Guys, Bill, not to hijack this thread but
Is the trans temp light an idiot light too? Or take an insane amount of heat to trigger?
Light comes on during grid cycling, so bulb is good, had trans smelling real toasty on shut down before and never a light,
I mean that's a good thing, but not if sensor isnt working...
Where is the sensor so I could try cleaning it up?
The trans temp light is supposed to go on at 240°F, tranny will drop out of lock up at the same time.
On a '97 the temp sender is inside the tranny and would be a real hassle to clean.
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