buddy of mine has a 98 gmc with the 5.7 vortec, 211k miles, it runs great besides a few problems. oil pressure on a cold start is 40 psi, warm idle is between 10-15 psi and cruising 50-60 mph is about 20 psi. Were trying to figure out if its the gauge, the pressure sensor, or the bearings are wore out. He says the truck has ran like that and ran just fine since he bought it with 170k. It also loses oil, sometimes the dipstick is dry, no leaking, no burning, the intake gaskets seem to be fine because the radiator and reservoir are always full. We have even tried 15W40 in it and it still loses oil. any ideas guys? I also changed the pcv valve recently..
'98 GMC 1500
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What is the hot idle pressure listed in the manual? My 92 GMC with a 305 called for 15-18psi hot idle in the manual. Lasted over 200k, never any engine problems.
One thing I don't understand, (and I have seen it mentioned before) is how you can say that the oil is disappearing but it is not leaking , and it is not burning it. Leaking I can understand, because leaks can usually be seen, but if it isn't leaking, it IS burning it. Maybe you don't see big clouds of smoke behind you, but it IS burning it. I once had a car that BURNED a quart of oil every 100 miles and when I told people why I had it rebuilt, they said "gee I never saw it smoke"
Nick1994
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Originally Posted By: Chris B.
I have a 1997 Sierra with the 5.7 Vortec and 84,000 miles. My cold start up oil pressure at idle is 50-60psi I think and hot idle is 18psi. Oil pressure hot while crusing is 40psi.
My 96' Chevy with the 5.7 Vortec and 159k when I sold it just over a year ago had this exact same oil pressure.
I have a 1997 Sierra with the 5.7 Vortec and 84,000 miles. My cold start up oil pressure at idle is 50-60psi I think and hot idle is 18psi. Oil pressure hot while crusing is 40psi.
My 96' Chevy with the 5.7 Vortec and 159k when I sold it just over a year ago had this exact same oil pressure.
i have a 91 c1500 (in extended family) and hot idle sits at 18 psi. been like that since purchase in 2007. i think your hot idle oil pressure is fine.
Same 98 GMC with a 5.7 and oil pressure is fine where that's at.
Mine uses oil too and no sign of burning smoke wise. The best option is probably Maxlife but that's not gonna cure it, it will slow it some possible. I've tried additives and all that, it is not too bad, about a quart every 2000-3000 miles.
Mine uses oil too and no sign of burning smoke wise. The best option is probably Maxlife but that's not gonna cure it, it will slow it some possible. I've tried additives and all that, it is not too bad, about a quart every 2000-3000 miles.
I have a 98 chevy silverado with the 5.7L with about 129,000 miles on it and my cold idle pressure is around 55-60 psi. Hot idle in gear is about 20-25 psi. Cruising with the engine hot it's about 45 psi. This is on the factory gauge. This is using a 5W-30 oil.
I bought this truck new and the oil pressure was slightly better when it was new but it has not gone down that much over the years and miles.
Wayne
I bought this truck new and the oil pressure was slightly better when it was new but it has not gone down that much over the years and miles.
Wayne
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