This is my sons site (he's got a first gen) but I have a issue with loosing oil pressure when backing up my trailer. After returning home from a 15 mile trip pulling my quaads on our utility trailer (total about 2k) I pull into the drive and position the truck to back the trailer in and the oil pressure drops to zero and the "check engine" light and the buzzer come on. After a few seconds, the pressure on the guage comes back and the buzzer goes off. About two years ago, I replaced the oil pressure sender and it worked for a while. Am I missing something?? Oil is changed every 3k with Rotella (last time to Premium Blue) and the motor has 165k. Oh yea, it's a 98 12V with Banks twin Ram intake and fuel plate, exhaust brake (DON'T WASTE YOUR MONEY, IT'S USELESS) 4" exhaust with Donaldson muffler,4x4 extended cab dually.

 

Since so many people seem to have problems with the sending unit, it may be just that again. I'd beg, borrow, or steal a mechanical oil pressure gauge from someone to make sure though, just in case there is a legitimate drop in pressure that can cause big problems or is indicating an existing problem. It may be just a bad electrical connector or wire too. Anytime pressure drops to 0, it's time to hook up a good gauge just to make sure.

 

I'd imagine you could find a cheap mechanical gauge. Right on the head of the oil filter housing/oil cooler, is a 1/8" NPT port you can tap into a for a gauge. Oil pressure sending units are notorious for going bad, but its not a sure enough thing to chance wiping out your bearings on.

 

Thanks. I have a cooper tube ran into the cab to diagnoise the lack-luster performance of the Banks exhaust brake, so I'll pull that over and hook up my old mechanical gause and run that for a while to ensure adequate pressure. MLS

 

whats the idle set at? my guess is if you bump it up a bit the problem will be solved. my '98 started doing this the day after i bought it. bumped the idle up and not one single warning chime in over a year.

i believe the source of the problem has to do with the new-for-98 interior and gauge package. the operating range on the oil pressure gauge is pre-set and if oil pressure drops below a certain value the guage drops to zero. i think the magic number is something like 26 psi. with the idle set too low when you shift into reverse the engine idles down and the oil pressure probably drops to something around 23-24 lbs, which according to the wonderful electric guage and sending unit is equivalent to zero pouds of oil pressure.

I put a mechanical gauge on mine and drove it util the gauge dropped and it was still holding 24 psi, fully warm and low idle (roughly 700 rpm). one other thing i noticed was on a cold start while the in-dash gauge shows about 50 psi the mechanical one i had read about 70-75 psi.

so long story short, check it with a mechanical gauge and then bump the idle up as necessary.

 

My 98 does the same thing.

 

There is a tsb for the 98's on this issue. It will simply turn your gauge into an idiot light but it will get rid of the annoying chiming.

http://dodgeram.info/tsb/1999/08-22-99.htm

 

My bet is the sending unit is bad especially if it was a generic autoparts one.
If you want the sender to last buy it from Cummins, you actually save money in the long run.

 

I need to do the same thing AGAIN because I, or more correctly the mechanic that did the work, did not listen and get a real Cummins unit. Does anyone happen to know the part number?

Thanks for the comment about the pipe fitting on the oil filter base. I was wondering if there was readily accessable spot to put a mechanical gauge.

 

From Cummins 3923200

 

is the engine full of oil?

 

Infidel,

Thank you for the info I'll write it in a better place this time.

Heykw,

I keep a close check on the oil level. Since I replaced the front main seal that was leaking, it does not use any appreciable amount. Even with the leak, it was only a quart every 2000 miles, or so, but the mess in the engine compartment was terrible and it was beginning to destroy the serpentine belt.

 

No need, let the internet store your numbers.
Most common part numbers can be found at the bottom of this page http://dodgeram.org/tech/dsl/Facts/96specs.html

 

GREAT! Thank you!

 

Instead of starting a new thread, I'll jump in on this one.

My 12v has "ding!"ed me since I can remember. New Cummins sending unit installed, still does it.

Mine shows up when you are driving, and put on the brakes to make a turn or stop at a light.

It's in the shop right now with a mech. gauge hooked up - the shop owner said it dropped down to about 30psi, then tried to dip a little lower before coming back up soon after you get going again.

So what is the min. psi we should legitimately be seeing on this thing? If mine is ok there - I'll check out the TSB to see about going that route.