Low Oil Pressure

[trickkid]

I have been reading through threads all day trying to find one that matched my symptoms AND had helpful replies. So, here is my issue...

2006 GMC Envoy Denali XL, 5.3L V8, 4WD, Automatic

Driving home last night the oil pressure dropped to zero and gave me the low oil pressure message. Pulled over, shut off the motor, restarted it and got oil pressure back, turned around and headed to the closest gas station to put oil in the motor (assumed it was low). I now know I have over filled it with about a quart of oil, but that is better than no oil. Got oil pressure back and was able to drive the rest of the way home with no issues. This morning, light came back on about 2-3 miles down the road, same issue, turn it off and back on and get some pressure back on the gauge for a short distance. So tonight after the vehicle has cooled down all day, I restart the motor to watch and listen for symptoms.

Great oil pressure when the motor is cold, right around 40-42. Once the motor gets to operating temp the pressure drops and trips the light. Turn off and turn back on, the oil pressure comes up to 15-18 and then slowly drops down again. Repeat process and the gauge always resets to 15-18 and then slowly drops again.

What I can determine from what I have read is that it is most likely a faulty oil pressure sensor for the gauge. The motor sounds normal so its not likely to be a faulty oil pump, and the gauge is consistent so its not likely to be a faulty gauge.

Thoughts, solutions, had this problem happen to you before and figured it out?

 

[kawaholic]

It seems like you're on the right track. I'd suspect the sending unit. Not sure if there's a way to test the sending unit or not. I'd borrow, rent or buy an oil pressure test kit and verify oil pressure that way. Once you've verified oil pressure, it'd be a pretty safe bet to replace the sending unit.
Hang tight, one of the experts should be along shortly.

 

[BRomanJr]

I have been reading through threads all day trying to find one that matched my symptoms AND had helpful replies. So, here is my issue...

2006 GMC Envoy Denali XL, 5.3L V8, 4WD, Automatic

Driving home last night the oil pressure dropped to zero and gave me the low oil pressure message. Pulled over, shut off the motor, restarted it and got oil pressure back, turned around and headed to the closest gas station to put oil in the motor (assumed it was low). I now know I have over filled it with about a quart of oil, but that is better than no oil. Got oil pressure back and was able to drive the rest of the way home with no issues. This morning, light came back on about 2-3 miles down the road, same issue, turn it off and back on and get some pressure back on the gauge for a short distance. So tonight after the vehicle has cooled down all day, I restart the motor to watch and listen for symptoms.

Great oil pressure when the motor is cold, right around 40-42. Once the motor gets to operating temp the pressure drops and trips the light. Turn off and turn back on, the oil pressure comes up to 15-18 and then slowly drops down again. Repeat process and the gauge always resets to 15-18 and then slowly drops again.

What I can determine from what I have read is that it is most likely a faulty oil pressure sensor for the gauge. The motor sounds normal so its not likely to be a faulty oil pump, and the gauge is consistent so its not likely to be a faulty gauge.

Thoughts, solutions, had this problem happen to you before and figured it out?

I had a similar problem, lost oil pressure while driving, stopped, made sure it was full, restarted and was ok for a short while then pressure dropped again.

Mine problem was sludge collected in the oil pan after a couple regular oil changes and then a flush treatment. (I bought the truck with high miles and it must not have been changed regularly) The sludge would fall off the pickup when engine was off then re-collect on the pickup screen as you drove.

My fix was to have the pan removed and cleaned out, no problem since.

I see you have 4WD, much more work than my 2WD was. Good luck.

 

[trickkid]

Well, mechanical test shows that it is in fact losing oil pressure. But does not explain why. The vehicle has a periodic misfire/stumble and when it happens, the oil pressure drops about 2 lbs. Trying to find out what the relation between the two could be. The really odd part is when it loses oil pressure, increasing RPMs has no effect on pressure, but restarting the vehicle brings the pressure back. Really confused, and now really concerned.

 

[CaptainXL]

Well, mechanical test shows that it is in fact losing oil pressure.

Losing pressure by how much???

So you removed the pressure sensor and hooked up a pressure gauge?

First thing to do is make sure you are using the proper filter and oil. Check the condition of oil after draining. You would be checking for metal flakes or any solids when draining. Make sure the filter is an ACDelco starting out. Some aftermarket filters give these engines fits.

Next thing would be to check your coolant and make sure there is no oil in there. This covers head issues.

Then after all that I would pull the pan and check the pickup tube o ring. Possibly replace pump if needed.

 

[trickkid]

Drained oil.... metal shavings!

 

[kawaholic]

THAT'S not good... Just curious, what's the mileage on the vehicle? Are you the original owner?

I was starting to think your problem might have been similar to BRomanJr's but it sounds like you've got bigger problems now.

Are the metal shavings magnetic?

 

[trickkid]

Cut open the oil filter, PACKED of metal shavings. I am pretty positive the rotating assy is chewing up the thrust washer and bearings, and the have been blocking the pick up assembly, causing the loss in oil pressure.

I just bought the vehicle a little over 2 months ago, right around 107K miles.

 

[jrSS]

Rod bearing??.... time for a rebuild.

 

[Showtyme]

I just bought the vehicle a little over 2 months ago, right around 107K miles.

That really sucks man. Sorry to hear the bad news. Did u get any kind of warranty when u bought it?

 

[CaptainXL]

There should be. If not mistaken Maryland law does not permit "as is" car sales.

 

[gmcman]

Cut open the oil filter, PACKED of metal shavings. I am pretty positive the rotating assy is chewing up the thrust washer and bearings, and the have been blocking the pick up assembly, causing the loss in oil pressure.

I just bought the vehicle a little over 2 months ago, right around 107K miles.

That's a bummer, hopefully there's some kind of warranty. Kinda points to the previous owner possibly having some type of knowledge of this. Any chance you could retrace the service to a dealer or even the last oil change? Perhaps you could find something in case you need it in your defense. Good luck.