Oil Pressure

waterloo88chev · 07-14-2007, 11:36 PM

i have a bit of a problem with my truck's oil pressure, and i dont have much of a vast knowledge of engines, so maybe a little help. i drive an 88 1500 V8 5.7 ... but i dont think its the original engine. it jsut seems to clean (well in a way) and stripped down to the bare essentials to be the original. the guy i bought it from said it was a 350, so we'll go off that. when cold, the oil pressure is normal, sits at 40 PSI, or just right above it. after just a few minutes when the engine heats up, the pressure starts goin wacky. when i slow down, the pressure drops way down, close to 0 at times, but usually around 10 PSI. as i speed up, the pressure goes back up. how high it goes back up depends on how long ive been driving, at first it will go back up to 40, but the longer it is, it usually goes back up to around 30 and sits there at cruising speed. because of this problem i regularly check my oil, and i dont really use much at all. there is pretty minimal oil anywhere around the engine, but its not dry as a bone. so im guessing that it is some gasket heating up, opening up.... and causing the pressure to drop without really losing oil? any help would be greatly appreciated. THANKS!

mudseeker · 07-15-2007, 07:10 AM

sounds like you may have a bad sensor.

75K30 · 07-15-2007, 10:48 AM

leaks and pressure in this case are not related. If you had a leak that bad, you would run out of oil and the engine would stop completely. Your oil pressure problem is a result of a tired engine. As the engine wears, the bearings have less tolerance, and the oil pressure drops. Cold oil is more viscous than hot oil, so the pressure is higher when cold. You are experiencing a normal thing. A chevy engine will operate at very low pressures, almost as low as a 8 psi.
You could also have a bad sending unit that is giving the gauge inacurrate measurements. The only way to verify this would be to install another gauge to make a comparisson.

waterloo88chev · 07-16-2007, 11:39 PM

alright thanks a lot guys. the gauge ive been going off of is an after-market gauge already, so i dont want to install another. im not sure if the original in dash gauge even works, so i cant really compare the two. but now i know that it can be normal, im not so worried about it.. thanks

07-14-2007, 11:36 PM	#1
waterloo88chev Senior Member Join Date: May 2007 Location: Illinois Posts: 177	Oil Pressure i have a bit of a problem with my truck's oil pressure, and i dont have much of a vast knowledge of engines, so maybe a little help. i drive an 88 1500 V8 5.7 ... but i dont think its the original engine. it jsut seems to clean (well in a way) and stripped down to the bare essentials to be the original. the guy i bought it from said it was a 350, so we'll go off that. when cold, the oil pressure is normal, sits at 40 PSI, or just right above it. after just a few minutes when the engine heats up, the pressure starts goin wacky. when i slow down, the pressure drops way down, close to 0 at times, but usually around 10 PSI. as i speed up, the pressure goes back up. how high it goes back up depends on how long ive been driving, at first it will go back up to 40, but the longer it is, it usually goes back up to around 30 and sits there at cruising speed. because of this problem i regularly check my oil, and i dont really use much at all. there is pretty minimal oil anywhere around the engine, but its not dry as a bone. so im guessing that it is some gasket heating up, opening up.... and causing the pressure to drop without really losing oil? any help would be greatly appreciated. THANKS!

07-15-2007, 07:10 AM	#2
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 6,374	sounds like you may have a bad sensor. __________________ i'd rather be hunting

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07-15-2007, 10:48 AM	#3
75K30 Senior Member Join Date: Jul 2006 Posts: 2,992	leaks and pressure in this case are not related. If you had a leak that bad, you would run out of oil and the engine would stop completely. Your oil pressure problem is a result of a tired engine. As the engine wears, the bearings have less tolerance, and the oil pressure drops. Cold oil is more viscous than hot oil, so the pressure is higher when cold. You are experiencing a normal thing. A chevy engine will operate at very low pressures, almost as low as a 8 psi. You could also have a bad sending unit that is giving the gauge inacurrate measurements. The only way to verify this would be to install another gauge to make a comparisson.

07-16-2007, 11:39 PM	#4
waterloo88chev Senior Member Join Date: May 2007 Location: Illinois Posts: 177	alright thanks a lot guys. the gauge ive been going off of is an after-market gauge already, so i dont want to install another. im not sure if the original in dash gauge even works, so i cant really compare the two. but now i know that it can be normal, im not so worried about it.. thanks