L10 Cummins. -one day good oil pressure and next day extremely low ISSUE

[Nathaniel McClain]

Like title says, one day I start truck and oil pressure is beautiful and the next day it’s horrible it goes below and sets off alarm but will increase with rpm but not good still

Everyday it’s a gamble if it’s going to be good or not.

I’m lost on what it can be so I’m consulting with some experts on this motor??

Thanks so much I’m advance for any help or insight

 

[Wayne M.]

Sorry I’m not an “expert” with the L10, I just know it’s a dandy engine. How many hours on it?
That said, I would start simple, and go for the oil pump bypass/ regulator. I may have it confused with the C8.3, but it might be in the same spot as the oil cooler, right side where the oil filter is. Maybe there is a broken spring?

 

[Nathaniel McClain]

Sorry I’m not an “expert” with the L10, I just know it’s a dandy engine. How many hours on it?
That said, I would start simple, and go for the oil pump bypass/ regulator. I may have it confused with the C8.3, but it might be in the same spot as the oil cooler, right side where the oil filter is. Maybe there is a broken spring?

I’ve heard of that but I’m still learning about these engines. I do love it. Great engine compared to my other cat trucks.

I’ll check that spot. I just didn’t know where I would find it. I tried looking before but got nowhere finding it

Thanks for the tip. I’ll see what I can find

Oh and honestly I forget hours. I know it’s high but it runs perfect.

 

[Wayne M.]

If you go on Cummins’ site, you can register the engine, and get lots of parts info and etc. I think it’s free to start.

 

[Nathaniel McClain]

If you go on Cummins’ site, you can register the engine, and get lots of parts info and etc. I think it’s free to start.

Wow that’s great I’ll check it too! Thanks

 

[Nathaniel McClain]

I could t find that oil regulator and Cummins didn’t have info on website but I did submit a ticket to hopefully hear back.

Any ideas?

 

[JR]

I'd double check it with a manual pressure gauge before doing anything. You can run one right off of the plug by the filter in your picture. oil pressure sensor on the L10 should be on drivers side, center to rear of Block. The one I remember was behind the fuel filter but that could be different depending on application and year. Should be a 3 wire sensor.

 

[Nathaniel McClain]

I'd double check it with a manual pressure gauge before doing anything. You can run one right off of the plug by the filter in your picture. oil pressure sensor on the L10 should be on drivers side, center to rear of Block. The one I remember was behind the fuel filter but that could be different depending on application and year. Should be a 3 wire sensor.

Yeah I think I’m going to do that personally just to make sure.
Do you know where the regulator is too?

 

[mwilson]

What is this engine in?? Electrical gauge or mechanical?

 

[Nathaniel McClain]

Sorry, it’s mechanical.
In a gmc white cab over

What is this engine in?? Electrical gauge or mechanical?

 

[JR]

Sorry, it’s mechanical.
In a gmc white cab over

The gauge is mechanical?

What year truck?

 

[Nathaniel McClain]

The gauge is mechanical?

What year truck?

Mechanical engine but also mechanical gauges
94 is year

 

[JR]

Single wire on sender?

The only wrench time ive had on an L10 is in a tractor but it was not mechanical gauge. Around the same vintage (Versa tractor).

Would still be worth checking out before proceeding. I just witnessed a mechanical gauge on an air compressor fail. Gauge was reading 70 psi yet the 150 psi safety kept lifting. After changing out the safety with no difference I threw another mechanical gauge on and wuala, new gauge was reading 160 psi. This a plain Jane pneumatic gauge, everything goes TU eventually.

 

[mwilson]

So if it’s mechanical have you located the sender for the low oil pressure alarm or is that part of the mechanical gauge??

Regardless oil pressure usually doesn’t come and go like that for long before inside pieces want to be outside pieces.

Get a test gauge on it pronto...

 

[mwilson]

And as JR mentioned are you saying that the gauge is mechanical or that the engine is mechanical....

 

[Nathaniel McClain]

And as JR mentioned are you saying that the gauge is mechanical or that the engine is mechanical....

I’m going to confirm all of this myself this week.

Gauge and engine are mechanical

 

[BLNRAY]

sounds like the oil pressure regulator could be sticking,if i remember correct you have to remove the pan to access it,i have a service manual for L-10 mechanical engine

 

[Nathaniel McClain]

sounds like the oil pressure regulator could be sticking,if i remember correct you have to remove the pan to access it,i have a service manual for L-10 mechanical engine

Thank you. It’s where my thoughts are too.
Is that a link to your store?

 

[Tuesdak]

X2 Double check the pressure. Many engines/transmissions have been needlessly removed and overhauled over bad (pressure/temp) gauges...

Does the oil smell like diesel fuel? I assume it's at the marks on the dipstick not over or under level. Do you do oil samples on this engine? Now is the time to send a sample in (even if you don't do samples). Chasing a problem like low oil pressure is best to have a sample rather than just dumping the oil for fresh oil. The sample can give you some clues as to oil contamination coolant/dirt/diesel. Viscosity could have thinned out due to contamination and an oil sample will show this. (Oddly oil samples don't report Biodiesel contamination as "fuel in oil" but will show low viscosity.) Further a sample can show you extreme metal or soot indicating a failure is happening before you ventilate the block.

If you do change the oil it's also a good idea to cut the old oil filter open and see if you can read part numbers in metal debris. Hopefully not. You do not have to change the oil to check just the filter.

 

[BLNRAY]

Don't have a store but maybe If I could figure out how to upload pictures I could help,and i think you can go to cummins insite and find what you need