Engine/Transmission (1994 - 1998) oil pressure

[Donald MacKenzie]

I have a 1998 Dodge w/12v cummins. It has 135k for milage. I have been noticing the oil pressure gauge dropping down to zero when I stop for a light or a toll booth. It goes back up within 5-10 seconds. I did change oil to Mobil diesel synthetic and the pressure problem started after that and thought that it might be too thin? I drained and changed to Shell rotella T and the pressure light has come on once in 300 miles. Help!!

 

[bheiting]

It might be something as simple as a bad sender, lose wire, or bad guage. That's
where I would start looking.

 

[DShaw]

mine did the same thing ... . changed the sending unit and all is well and its a pain to get the connector keeper off so dont go to yanking it without getting it out

 

[budnate]

mine just started doing it also... is it easier to go at it from the top or bottom? thought I read somehwere it was real tight to get at it by the starter?? and what size socket yanks it loose?? thnx.



B.

 

[PBJ2500CTD]

If there are no additional rattles and odd noises the oil pressure should be good. I had a similar occurence that was caused by the oil pressure sending unit. I checked for lots of oil flow at the rocker arms in the valve cover. The most anoying part was the check engine light and chime going on and off for the next 450 miles of our trip.

 

[CumminsPower98]

Its likely the sender but may also need this TSB done: TSB 08-22-99



I fixed mine twice by replacing the sender. The second time it didn't last long at all. I had the TSB done next. The TSB is a PCM flash to reprogram the point at which the PCM says the oil pressure is too low and sets off the chime/light. It will however make the gauge a little more idiot light like as it won't read pressure changes below about 40. I'm not sure now of the bottom number where its supposed to report no pressure but I think its somewhere around 6-7 psi.



If you have the TSB done it might be wise to print the TSB above and take it with you. I went to a dealer in Northern IN when I was driving OTR to have it done the tech had never heard of it and he was also unable to find it online in their system even when I gave him the number. My first and only Dodge dealer experience was a bad one. The first time before he had the TSB in hand he verified oil pressure and told me I may need a sender and charged me. I didn't have time to come back right then as I needed to head off with an RV. I came back for another trailer later and went in again only this time I had the print out. This time the guy was able to do the job and again I was charged. I left and headed down the street in town but noticed right away that my fuel pressure gauge wasn't working. I pulled over and popped the hood to find fuel all over in there. Turns out the guy had knocked sender hose off at the pump banjo bolt. Sent an email to the dealer explaining my bad experience and that I wanted my money back for the first visit. I let them know very clearly that I was a mechanic myself and knew exactly what this job involved so not to try to mess with me. They went ahead and refunded my first visit so that part turned out well.

 

[HCannon]

Got a 98 that is doing the same thing, when I come to idle the gage will go to zero for a short time and then come back to near 40 pounds. Budnate, did you find out what size socket needed? It sounds like the place to start is replacing the sending unit.



Harv

 

[CumminsPower98]

You need a special sending unit socket for best results. Most any parts store should have them. If a regular socket will work I couldn't tell you the size it would be.

 

[budnate]

dunno... ... . Cummins ordered in a new sending unit for me, I need to make a run and grab it, once I have in my hand I will let you guys know.



do you guys know the cummins part number for the sending unit on a '98 12V?



cummins parts guy on the phone was confused... imagine that. . when I asked for the sending unit. just to make sure they got the right one before I drive over, its kind of a hassle to get there.







B.