2002 GMC Envoy

CHRISTINALYNN

MEMBER
2002 GMC ENVOY
6 CYL
4WD
AUTOMATIC
127,000 MILES

My 2002 GMC ENVOY was in a few shops last year because the oil pressure was dropping when idling. The warning light to stop engine came on. This only seems to happen after the car is warmed up. One place replaced the sensor but it happened again. Finally I brought it to the dealer, who checked the diagnostics and could not find a problem. He could not even get the problem to occur for him. He reset the computer and since last sept. It has been great. Today was the hottest day of the year and after driving 13 miles or so with the air on full blast it happened again for the first time since fixed. There are 126000 miles on it and the engine is quiet with no knocks whatsoever. The car is normal pressure then when in idle the pressure drops to zero, yes zero. I was told if it was really zero it would not even run. I was also told by another mechanic that he let the engine run for hour and half while on his machine and while the car has very low pressure, it never went below spec. He wanted to replaqce the engine! Please help! Any idea whats going on?

1 Reply

HMAC300

MECHANIC
48,601 POSTS

First manually check the pressure with a manual pressure guage, not electric. If you hear no knocks then I am going to assume the engine is in good shape. You may have a bad ground going to the sensor and it is losing ground under certain circumstances. Then use a QUALITY oil filter and I cannot stress this enough. The ones I consider quality are AC- Purolator-Wix. Motorcraft doesn't seem to be to bad. That can make a big difference. Also try to find one that has a check valve in it, it will be easy to see as it will be rubber under all the small holes in the filter.