Oil Pressure Issues

[CrewCabDiesel]

This one has me stumped, I decided to add a mechanical gauge to the truck and the original plan was to put a T in at the factory oil sending unit and add a mechanical gauge, low and behold Cummins uses a weird side end on its sending unit and I can't find the right plumbing parts. So, I decided to hook up to the extra oil port on top of the oil filter housing which uses the standard 1/8 pipe thread. So I get the new gauge hooked up it shows 25 psi cold, so now I'm worried, rob the mechanical gauge off my Imperial(I don’t trust the Factory oil pressure gauges on Mopar’s), same thing, now I go right to the housing with the gauge thinking I screwed up the new oil lines, no such luck engine is warmed up pressure at idle is 11 psi at the mechanical gauge. Factory gauge is showing about 50 psi cold idle and around 30 psi at full engine temp. Motor was rebuilt little over 100K, no problems. If I had not added a new gauge, I wouldn't be looking for an issue. My 2001 Ram I set up the mechanical gauge and had 70 PSI cold at 300 K

Any Ideas?

Thanks Kyle

PS if you know the thread size and type of the oil sending unit please let me know

 

[Tuesdak]

This engine has an oil pressure switch only. The oil pressure gauge is for entertainment purposes only. It lies and displays what the ECM thinks the oil pressure should be.

Get an oil sample and send it off to a lab ASAP! Then change the oil. Cut the oil filter open and look for part numbers in the filter media. Modern times mix biodiesel into the diesel fuel and that can contaminate the engine oil resulting in oil pressure loss. (More an DPF issue than your truck.) You could simply have a fuel leak causing oil dilution.

When they rebuilt my engine they did NOT use a new oil pump. They paid for their lack of vision by getting to rebuild the engine a second time in 500 miles now on their dime. The oil pressure before the rebuilds was rattling the valves in the oil cooler/filter area. And they reused the oil pump...

Couple of valves in the oil cooler that can contribute to low oil pressure.

After you find out the cause of the low oil pressure it's best to send the turbo out for new bearings/rebuild. The low oil pressure episodes took the bearings out of my turbo to the point the wheels were wearing on the housing.

 

[CrewCabDiesel]

Thanks for the reply, just did a 100k oil sample all very good shape, as for the motor build, I did everything but the machine work, built several Cummins and well as a bunch of race and stock motors. Ill have to look into the pressure switch again. Anyone had problems with the oil pressure regulator valves?, that is something I overlooked.

 

[DavidC]

The regulator is something to look at. Have only seen a max of 2 problems, at least one was I believe the piston (for lack of a better word) was stuck.

 

[CrewCabDiesel]

I really didn't pay attention to the oil filter housing, too busy filling ring gap I guess. Got the new value and I am going through my extra housing and installing a new Cummins oil pump. Current oil pressure a cold 25 psi idle to 60 psi @ 1500, full temp idle 11 psi, 40 psi @ 1500 rpm.

 

[AH64ID]

The idle pressure does seem a little low, but the 1500 rpm pressure is about what I recall with a real pressure gauge on my 05. I did have my 05’s gauge in the port by the ECM in the cam journal so it will normally read lower than the filter head.

One thing I’ve seen cause low pressure is the wrong oil cooling jets, or adding the 2nd set of jets.

 

[sag2]

Although not what most would like to see, that oil pressure is completely acceptable to protect the engine. The oil pressure switch is right at 6 PSI, so if the cluster has never alarmed you have had plenty of oil pressure.

 

[AH64ID]

Although not what most would like to see, that oil pressure is completely acceptable to protect the engine. The oil pressure switch is right at 6 PSI, so if the cluster has never alarmed you have had plenty of oil pressure.

This is also correct. 10 psi at idle and 30 psi at rated rpms are the numbers I recall.

 

[cerberusiam]

The pressure is not out of spec but lower than most would agree is good for a tight engine unless the rebuild specs were on the high side. From my experience, drop the pan and replace the gasket on the oil pump pickup and GLUE THAT SUCKER ON!

 

[sag2]

Usually if there is a leak on the suction side the pressure will be slow to build.

 

[CrewCabDiesel]

mechanical gauge is slow to build pressure but its going through 10 feet of hose, dash gauge very quick to show pressure. Problem has to be either the oil pump or oil pressure regulator or does anybody else have suggestions?
Thanks
Kyle

 

[Tuesdak]

There was a 5.9 sold on here that lost an engine under factory warranty due to the oil pump gasket I recall.

My builds had the 2nd set of piston cooling jets installed that contributed to the low oil pressure with a worn oil pump. The oil pump "disappeared" before I could look at it during the warranty rebuild... After rebuild with a new oil pump the pressure was better after a warm up run on the freeway. The turbo didn't last very long after the 2nd rebuild.

Again the dash gauge is worthless.

 

[cerberusiam]

Could still be a partially compromised gasket on the oil pump pickup. Been there done that. 3000 miles on the rebuild and oil pressure started dropping at an idle one day, the next day no oil pressure at all. After new PR valve and oil pump the pan came off to get the problem fixed. Sucked the gasket in where it bolts to the front cover. Brand new Cummins gasket also and there was no observable issue with mating surfaces

If everything is good the pressure jumps pretty fast at the oil filter. Once the line is full of oil it should jump up pretty fast, if it rises slow and doesn't go as high as it could I would check it all. IIRC, now have 60-65 psi cold with 20-25 psi hot after new oil pump, PRV, and gasket glued on the pickup tube.

 

[CrewCabDiesel]

I'm hoping its in the oil filter housing, I used the Right Stuff (we call it Cheese wiz )to glue the pickup gasket on as well as the pan and just about everything else. Can the pan be pulled on a 4X4 with motor in the truck?

 

[cerberusiam]

If you glued it on it should be fine, unless the tube cracked. The pan can be pulled in the truck.

 

[CrewCabDiesel]

Here is a new one, as I loosened first two bolts and the pump popped out on that end a 1/4". put a straight edge on it, pump appears to be straight. Pump has almost no wear everything is within tolerances. Could I have somehow put the pump in wrong during the rebuild? I know I did not use the torque sequence, (just read that is required in my manual) could I have that cocked the pump some causing a loss of oil pressure? Not going to chance it, I am going down to Ocala FL Cummins dealer and picking up another oil pump tomorrow. Oil housing parts will be in Wednesday, I have an extra good oil filter housing laying around and will be installing new bypass valve and spring (getting it from the dealer for $20, both are discontinued) Also the other brass pressure relief valve and the oil cooler (Cummins part) My current oil cooler has 400K plus miles on it

 

[CrewCabDiesel]

Well all new Cummins parts in the oil housing including oil cooler, new Cummins oil pump, no idle pressure change, still 11psi full temp. picked up 8 psi at 1500 rpm. Oil pressure slow to build and change on mechanical oil pressure gauge still.
Unless anyone as any other ideas I guess its time to pull the pan and check the pickup gasket and bearings. Would it be ok to drive the truck with current oil pressures?
Thanks Kyle

 

[Ozymandias]

When you have driven for 100K Miles with it, have no suspicions noise from the engine, then yes you are fine to drive it.

As said, without your attempt to install a manual gauge you would have driven it on to right.

Right now I think the rebuilder messed something up, we had reported such cases before when they forget a plug in an oil gallery or there was a missing piston cooling oil jet and other nice mistakes.

Pulling the pan would be my way to proceed to. Maybe you find the missing part at its bottom.

 

[cerberusiam]

Missing plug in a gallery would equal no oil pressure. What could have been done is they installed both saddle jets AND j-jets or the saddle jet plug(s) are gone.

 

[CrewCabDiesel]

Interesting, when the pan is off I'll look for those. Yes I would have never been to question the oil pressure if I hadn't put in the mechanical gauge, no weird noises, runs very strong and I have pushed it and overloaded so many times. I just like most people believed that the OEM gauge really showed REAL oil pressure. Silly me
So it might be a really good idea that any owner of a Dodge Ram get a mechanical oil pressure gauge.