Hello all, my friend has a 1998 chevy 1500 with the 5.7 vortec engine in it. When he starts the truck the oil pressure is normal....with a little blue hint mixed with a looot of thick white smoke. After the truck warms up the oil pressure drops super low below 20 psi even with acceleration, the white smoke will clear up with no blue though. I did a compression test and got between 160-170 except on two cylinders. Number 4 was 190 and number 6 was140. Any ideas? I was going to replace the oil pump for the oil pressure but the compression numbers make me think the rings could be bad.

 

Hey yall ~ new to forum but would love to hear what people have to say on this topic. I have a 98 K1500 with a 5.7 vortec and 167K miles ... love this truck and will only replace once it decides to leave me for good.

Anyway, for the last couple years the truck I've had a rather odd issue. Truck runs great (no noticeable loss of power, no unusually noises in the engine, no noticeable smoke, starts right up...) although when I decelerate quickly (like at a red light) the oil pressure falls flat and check gauges light comes on. After idling for a few seconds the oil pressure returns to normal.

Much like leppek11, I too was thinking oil pump ... thoughts?

 

Yeah I'm thinking the rings are bad because the rings are allowing oil to pass and burn some oil and thats why you got all that smoke and low compression because you are losing compression through those bad rings. For the oil pressure I am not sure but I would say for leppek11 and livin4mt that the oil pumps need to be changed.

 

Try running a little thicker oil in like 10w-30. If the smoke lightens up a little bit its your rings. The rings won't cause as much of a problem with thicker oil not being able to move through as easily

 

May also be a Idle air control module along with worn out rings

 

my truck doesn't smoke,runs great,265000+ miles. gonna install a factory rebuild next year and keep my truck til i die. my oil pressure guage dropped to 0 . just need a tip how to see if it's the pump or the guage. used to do all my own work but i'm kinda lost since the 80s model

 

Im having the same oil pressure trouble. Ive changed the pressure sensor. and still drops when I come to a stop. All I need to know is how to check the oil pressure myself before I drop the pan and replace the pump. Ive just gone round and round with computer problems so please dont respond by giving other scenarios of what else it could be. I only want to check the pressure. Thanks, Tracy