Workhorse 8.1L Low Oil Pressure

theoldwizard1 wrote:
You need to verify that the sending unit is working properly. The only way to do this is to remove it and temporarily screw in a mechanical gauge. Hot idle oil pressure is the most important. You should be able to buy a mechanical gauge for less than $50.

If your original sender WAS working properly, damage likel has already been done to your engine.

i agree, hook up a mechanical guage and see what its really doing or hook up a T fitting so you can run both the mechanical and the original and compare the readings, would also be nice to check to see what the oil temp is also doing too, as the oil will thin out as it gets hotter..

Hank MI wrote:
2003 and only 5k miles, is this a rebuilt/replacement engine? How long has this been happening? Did it occur before the last oil change?

Took the words out of my mouth....

You need to verify that the sending unit is working properly. The only way to do this is to remove it and temporarily screw in a mechanical gauge. Hot idle oil pressure is the most important. You should be able to buy a mechanical gauge for less than $50.

If your original sender WAS working properly, damage likel has already been done to your engine.

how hot is the engine when climbing?

2003 and only 5k miles, is this a rebuilt/replacement engine? How long has this been happening? Did it occur before the last oil change?

I would suggest that in future oil changes that you use a 2 quart filter(AC Delco PF932), instead of the standard 1/2 quart filter. The oil filter costs only a couple of bucks more and you have to add an extra 1 1/2 quarts of oil but this will give you a little extra oil for cooling purposes, four times the filter capacity, and a little bit of a reserve if an oil leak starts.
If you are smelling oil, there is a leak somewhere and I would start with your last oil filter change. With an engine that has only 5,000 miles, I would look for a mistake made by the last mechanic(?) that worked on your vehicle. Things like an oil change, etc are usually performed by the newer, least experienced, mechanics at the shop. As part of their learning process, many do make mistakes, at your expense.

I'm just punching holes in the sky here, but it may be an oil drain-back problem. Something is restricting the oil from draining back form the heads. Plugged drain back holes, wrong gaskets, etc. The oil smell makes me think this may be the problem. If you are climbing, you are at a higher RPM, which puts more oil in the top end. Possibility.

Thanks for all of the info, I failed to mention that I smell oil when this occurs, the engine is very sluggish when pulling the hill and the warning comes up for several seconds and then goes off by itself. Both the oil and filter were changed at the dealer during normal maintenance and the used an AC Delco filter. The oil level is full and appears clean. I haven’t changed the oil sender unit, but the oil smell (nothing visual) makes me think it is more serious.

THe advice above is good. But incomplete

Suspect list
Low oil LEVEL (Pump sucking air)
Bad Oil Sensor (These already covered)
Dirty oil filter (how long since last change)
Oil past end of life (Likewise)
Worn bearings and such in engine allowing oil to escape too easily (major overhaul, This is more popular in Ford engines than Chevy and one of the reason I"m not a Ford Fan. there are more).

Worn Rings (Likewise major overhaul)

Worn Oil Pump (Not as major)

ANd the ever popular Loose Bolts or screws.

4x4ord wrote:
Sounds like your oil pump is sucking air when the oil runs to the back of the sump ... maybe your oil pick up tube has a pin hole?

Sounds like something like that is going on since it happens when climbing a hill. Thing is the pickup is in the rear at the deepest part of the pan. Oil level would have to be really low.