OK Guys, here's one for the gang.

My '91 D350 Dually 2wd ran well over the past week. Took it on a road trip towing a 24' Travel Trailer with 2 ATV's on the bed. Pulling into Los Alamos up a steep grade in 3rd gear. I pulled over to sight see, shoved in the clutch and let idle. The idle dropped lower than normal, and the oil pressure gauge bottomed out and and the warning light came on. I pressed on the accelerator a little, popped up the idle to a fast idle (by sound) and the oil pressure jumped up and the warning light went out.

This happened an additional two times over the week, each after having run the truck a little harder than normal. Other times, after a hard run, it behaved like usual.

Just before the trip, changed the oil (rottella) and filter (STP). The oil has remained at full with normal appearance and feel (slick).

I have plans to add additional gauges, but have not felt the need for them yet as the truck has not been BOMB'd.

Any suggestions would be appreciated. (BTW - Fuel mileage ranged from 14 - 19 mpg towing depending on headwind, grade and how hard I was in it)

 

First thing I would do is change the sender. This sort of thing happens fairly often, and a new sender clears it up.

 

I sec. it. Replaced the pump pressure spring,turned idle up(which helped temporarly) replaced pressure sw and now I idle itdown evan lowerthen before with out any problems I would start with sw.!!!!

 

Thanks, I felt that it probably was a sensor/electrical due to the fact that under load it performed as expected. Any way, a new sender is a cheap place to start.

Rich

 

Where is the pump pressure spring located?

 

In the filter mount. It's under a plug near the front on top of the mount. Remove the plug and the spring is directly underneath.

Rarely gives any trouble.

 

I had the same thing happen to me at the top of a high mountain pass. I really struggled between beleiving the gauge and shutting it down or let it run long enough to cool the turbo. I kept it running...

 

Yeah, freaked me out for a moment, then realized that with a little pressure on the 'go-juice' the oil pressure came up. The water temp was looking good so I only worried a bit. I learned somewhere in the past that stopping an engine after a hard pull up a mountain is hard on engines... something about all that excess heat just boiling the oil and warping heads.

Rich