I have a 2003 GMC Envoy with the 4.2L. If it were running well it would be worth around $2k.
The fake OEM gage started reading low oil pressure at idle when warm. The engine didn't sound oil starved when reading low oil pressure. The only strange sound the engine ever makes is a chattering sound when the throttle is released which occurs regardless of oil pressure readings. I'd guess that is probably the timing chain but not totally sure. I put in a new oil pressure switch because it is a common failure on GM vehicles. The new switch didn't change anything, so i installed an aftermarket gage to confirm the oil pressure. The aftermarket gage indicates the oil pressure is about 75psi when cold at idle. The engine's oil pressure drops lower than the aftermarket can read at idle once warm.
Plugged oil pickups is a common problem on these 4.2l engines. The front axle is routed through the oil pan, so removing the oil pan would take more time than the vehicle is worth. I filled the oil pan with MEK through the dipstick and let it soak for about a week. Although a lot of contaminants were expelled, there was no change in oil pressure. I suspect the oil pickup wasn't the problem.
My best guess is the problem is caused by worn out bearings. The vehicle isn't worth enough money to bother rebuilding the engine. It probably isn't even worth enough to swap the engine.
At this point, my plan to to drive it until it kicks the bucket. I'm wondering what type of oil i can use to delay it's dirt nap. What oil would you recommend in the summer and would you change that recommendation at zero degress F? Does thicker oil cause problems with valve timing solenoids?
The fake OEM gage started reading low oil pressure at idle when warm. The engine didn't sound oil starved when reading low oil pressure. The only strange sound the engine ever makes is a chattering sound when the throttle is released which occurs regardless of oil pressure readings. I'd guess that is probably the timing chain but not totally sure. I put in a new oil pressure switch because it is a common failure on GM vehicles. The new switch didn't change anything, so i installed an aftermarket gage to confirm the oil pressure. The aftermarket gage indicates the oil pressure is about 75psi when cold at idle. The engine's oil pressure drops lower than the aftermarket can read at idle once warm.
Plugged oil pickups is a common problem on these 4.2l engines. The front axle is routed through the oil pan, so removing the oil pan would take more time than the vehicle is worth. I filled the oil pan with MEK through the dipstick and let it soak for about a week. Although a lot of contaminants were expelled, there was no change in oil pressure. I suspect the oil pickup wasn't the problem.
My best guess is the problem is caused by worn out bearings. The vehicle isn't worth enough money to bother rebuilding the engine. It probably isn't even worth enough to swap the engine.
At this point, my plan to to drive it until it kicks the bucket. I'm wondering what type of oil i can use to delay it's dirt nap. What oil would you recommend in the summer and would you change that recommendation at zero degress F? Does thicker oil cause problems with valve timing solenoids?
