Oil Pressure

[Bob4x4]

Bob,

I understand if I had no oil pressure at all times but it only occurs when the engine is warm and when at an idle. I think that is why they are looking at the ECM. When they hooked a positive gauge to the top of the oil filter there is pressure within specs, same goes for the check at the oil pressure sender port on the drivers side of the engine, however the gauge and the computer says the oil pressure is zero. Most confusing.

puller

Ok I misunderstood i thought you had a gauge on it and no pressure at start up

 

[Bob4x4]

Mike there is a cluster self test that will show if the pointers are doing what they should and the inputs and outputs can be monitored. An imteitant problem becomes tougher

 

[sag2]

I would start the engine and unplug the sender. Does the pressure indicate zero? If so then cut the sender wire at the ECM (or slide out the pin if you have the tool). Does it then show pressure or zero? That checks the input circuit. Then does the pressure show zero in the ECM and the cluster, or just the cluster?
Remember, this is just a simple ground circuit. When there is no pressure, the circuit is taken to ground through the switch. If there is pressure (>6psi) the circuit is always open to ground. The ECM sends the pressure message message to the cluster who then determines where to place the needle based on temp and RPM.

 

[puller]

Thanks to all who have responded, The problem has been found. It would appear that the oil pump is bad, and maybe several other internal parts are having problems.



puller

 

[mwilson]

Thanks to all who have responded, The problem has been found. It would appear that the oil pump is bad, and maybe several other internal parts are having problems.



puller

Oil pump failures are almost unheard of on these engines. That is a shame.



Were it me and the results were pointing in that direction rather than the pressure regulator I would pull the base first and make sure that the sump was tight to the pump inlet before tearing into the front UNLESS they are suspecting bearing damage.

Even then, the rod and main bearings can be checked with the pan off without removing the engine. Start at the rear. Number 6 rod bearing will suffer first if there is a shortage of oil, as I recall.



Mike.

 

[sag2]

OK, so now I'm confused. You said the mechanical gauge showed pressure. If that is the case, how can the pump be bad?

 

[cerberusiam]

It would appear that the oil pump is bad, and maybe several other internal parts are having problems.

Are you sure they aren't just grabbing at straws now? If the pressure check at the pump head and sensor gallery was good then it cannot be the oil pump. Did they just do a random cold check on the oil pressure and ignore a warm check?

 

[puller]

I have to apologize the first reading was done by the dealer, I purchased a positive gauge and install at the oil port on the top of the filter, when the engine warmed up it only had 5 lbs on pressure at idle. I do think the pump is bad.

At his point if the new pump does not correct the problem the choices are a new truck or a rebuilt engine. I cannot afford a new truck right now but I think I could swing a new engine I would have to find a shop that could do the work, any suggestions?



puller

 

[cerberusiam]

Yep, something is wrong somewhere. At 5 psi the ECU will think there is no pressure. It is probably lower at the sensor. The dealer cheched it cold and called it good. It coul be the relief valve on the pump or other issues. No way to really tell unless you replace the filter housing and relief valve to see if that helps.

 

[HBarlow]

I have to apologize the first reading was done by the dealer, I purchased a positive gauge and install at the oil port on the top of the filter, when the engine warmed up it only had 5 lbs on pressure at idle. I do think the pump is bad.
At his point if the new pump does not correct the problem the choices are a new truck or a rebuilt engine. I cannot afford a new truck right now but I think I could swing a new engine I would have to find a shop that could do the work, any suggestions? puller

My suggestion is first follow cerberusiam's and other's advice to make sure the problem is the oil pump. A failed oil pump is an extremely rare event in a Cummins engine. Cummins is so certain it won't happen most of the trucks if not all since 2001 have used a simulated oil pressure sender in the ECM to give the driver a warm and fuzzy feeling. I have never heard of a failed pump and I think Mike Wilson posted a couple days ago that he has not either. Mike is parts manager in a large Freightliner dealership in ME with multiple store locations and has been in a truck store for many years.

IF, and I emphasize IF, the oil pump turns out to be bad and bearings, rings, etc. are worn because of it, my advice is buy a Cummins factory rebuilt engine with a warranty. Many shade tree mechanics can replace parts and call it a rebuilt engine, buy they are not all as skilled as they may think they are.

 

[puller]

I checked the relief valve myself and it was free and the spring measured 2. 6 in in length I did not have anything to check the tension. At his point in time I agree another engine in our future.





puller

 

[mwilson]

I checked the relief valve myself and it was free and the spring measured 2. 6 in in length I did not have anything to check the tension. At his point in time I agree another engine in our future.


puller

There are two valves in the oil cooler / filter head unit. A relief valve and a regulator valve IIRC. I'll look it up before morning and post it using my '06 for reference. These valves have caused issues on member's trucks.


Anything else you can share?.
How many miles on the truck?
Was it using oil previous to the low oil pressure condition?
Had it been run low on oil?
Does it have the OEM air filter box with stock filter element?


I am serious, you just don't see oil pump failures in these "B" engines. It is a simple and bullet-proof gear to gear unit.
All things are possible, but tell us everything you know. It could save you some serious cash.

Mike.

 

[puller]

I checked the relief valve myself and it was free and the spring measured 2. 6 in in length I did not have anything to check the tension. At his point in time I agree another engine in our future.





puller

 

[cerberusiam]

I checked the relief valve myself and it was free and the spring measured 2. 6 in in length I did not have anything to check the tension.

\

It is more than spring length and tension, the seat may be the issue and that is harder to check. Your choice, could be you have a rare failure or something simpler.

 

[DogramTD]

Puller, I have had the same issue with my truck since 2007 when I had 34k on the motor. I have done many things to remedy this short of dropping the pan to inspect the pick up and pulling the pump. I find if I park it pointed downward on a slight decline, it always builds pressure, problems occur when parked on incline. Ill post more on this when I am at a normal pc and not my phone.

 

[RVTRKN]

Before I would replace an expensive engine, I would drop the pan and inspect it, replace the pump and then see what happens, as far as bullet proof, if its mechanical it can break.

 

[BLNRAY]

have found pick-up tubes cracked,welds come loose and sucking air. oil pressure killer

 

[puller]

Here is an update to the oil pressure problem.



I took the truck to another dealer and it is in fact the main bearings. They claim that I have 3 injectors that are bad and diluting the oil thus causing the problem. So a new engine is being installed should be ready in about a week.



thank all for your input.



puller

 

[puller]

The new engine has been installed and it runs just fine.



Now comes questions.



What are the indications for bad injectors? Smoke? increased oil level? loss of power? I had none of these. Can someone tell me the answer to this.



puller

 

[jhenderson]

Hard to believe the oil was diluted enough to roach the mains but not raise the oil level.