I started my truck this evening and had no oil pressure on the gauge. When I reved it the pressure would go up to the normal range. I thought maybe I blew the pump seal and was filling the crank case full of diesel, but the oil lever is fine (although the oil does look a little thin). Since it wasn't rattling I drove it home. The gauge kept falling until it was back to almost zero. Still, it sounds fine.
Probably the sending unit right?

 

Start with that.

 

If you've got a spare mechanical gauge lying around, check the pressure just to be sure.

 

Like jimbo said the stock gauge is not very accurate try a manual gauge.

 

Thanks guys. I do have a spare mechanical gauge that I was thinking about hooking up to test with. I'll let you know that I find.
-mark

 

My oil pressure has an optional audible signal available on only high mileage engines: starts out rattling loudly, then over about 30 seconds as the pressure needle climbs to normal and all the wear spaces fill with oil the rattling reduces to a barely acceptable level. I turn up the radio and move off , ...

 

Yea, I don't realy want to go there...

 

Deleted by author, move to new thread.

 

Hey mhup., my 91.5 just started doing the same thing, gon'a try to get mech. gauge make the test, sure hope it's only our stk., gauges!!!

 

Well, I tee'd off my bypass filter port and I am pulling down 50psi hot on the freeway and 30PSI at idle. The factory gauge subits othwise....

 

You're well within specs, Mark. Cummins specs a minimum allowable of 10psi at idle and 30psi at rated speed (2500RPM).

 

Yea, I was pleased and releived to see those numbers.

 

Had the same thing on my 2001 at 10K miles, sender was replaced (no pants cleaning required after seeing that oil pressure at 0, honest!), no problems for the last 10yrs.