Engine/Transmission (1994 - 1998) Oil Pressure Fluctuations

[dieselpilot]

I have a `95 3500 Cummins with 198,000 miles. Recently , the oil pressure gauge has begun to behave strangly. The needle normally stays just to the right of center (42psi) like a rock. Now after driving for an hour or so, the needle will begin to fluctuate a bit, getting larger and larger fluctuation until the oil pressure reads zero. The oil idiot light never comes on, the oil (Mobil Delvac Synthetic) looks fine and is full, and the engine makes no strange noises. If I push the clutch in and go to idle, the pressure jumps right back up to 42psi. I`m thinking with something like a sending unit or gauge, not the oil pressure regulator or suction tube. Anyone had a similar problem? Thanks

 

[TPCDrafting]

Do a search on this subject, if it's the same that happened to mine, there is a TSB on this. Mine didn't fluctuate, it would just drop to zero. There is plenty of reading on "oil pressure guage"

 

[JohnE]

<em>&quot; ... Anyone had a similar problem? ... &quot; </em>



Yes. it is probably your sending unit. I replaced mine and it cleared it up. also got a defective one so that was swapped inside a month.

Get a Chrylser sending unit socket, too. PIA without, but pretty easy with. AND Don't wait too long before replacing the unit. Mine starting puking a lot of oil at the end.

 

[dieselpilot]

Thanks guys- I should have gone to the archives in the first place. Now a dumb question- do you need to drain the oil to pull the sensor or is the majority back in the pan? Thanks again.

 

[illflem]

No need to drain

 

[JohnE]

archives?

sometimes the archives are as useless as ... ... ... (you fill in the blanks). I never seem to retrieve the data I want without a great deal of effort.

Besides, it really helps the newer members to see these things posted fresh. Thanks Dieselpilot



I notice in my original post the bit about puking oil was not emphasized enough. I lost close to 2 quarts of oil in a few days after the original sending unit died. (The second replacement was simply due to a defective electrical element and never lost oil. )



Funny thing is the original sending unit was the source of a mysterious oil leak I could not locate for over a year. It was only a few drips, but very obvious on the trany lines and oil pan.