Chevy 350 making only 3 to 5lbs oil pressure idling when warm.
- Thread starter WillBrinkhoff
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I'd totally run 20W50 unless you're positive you must salvage this motor. It'll buy you time, then cross the bridge when it comes.
Dunno why people think 20W50 is too heavy in a tired, pushrod, domestic V8. These weights used to be way more common when manufacturing tolerances were not what they are today.
It's far from a SBC but I had an '80 Audi 5k with the I5 that reco'd 20W50 in the owners manual.
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Dunno why people think 20W50 is too heavy in a tired, pushrod, domestic V8. These weights used to be way more common when manufacturing tolerances were not what they are today.
It's far from a SBC but I had an '80 Audi 5k with the I5 that reco'd 20W50 in the owners manual.
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Using heavier oil in high mileage 5.7L Chevy
I have a high mileage(95k+ miles)1995 Chevy Extended Van w/ a 5.7L engine. The owners manual calls for 10w-30 oil. However, when idleing the oil pressure dips to the next to lowest mark for oil pressure, I think 20# psi. As soon as I give it gas, the needle jumps to about 60# psi. Is it ok to...
bobistheoilguy.com
What does the pressure read at say, 1500-2000 RPM?
OK..... Oil doesn't fix problems. If you have an oil pressure issue it can be many things from a clogged oil pump pick up, bad pump, stuck relief value. That low, I would be surprised if you're getting adequate lubrication of the main bearings and valve train. Take it to an expert for an evaluation. Could be a bad sending unit? But, if indeed there is a mechanical issue and you get it diagnosed now it could save you thousands. If you spin a main bearing there's a high probability that the crank could be ruined. Or, a piston could impact the valves, and it gets worse from all the debris circulating. If you need lawyer you don't get legal advice from Billy Bob Jo, you go to an expert. You could NOT listen to good advice, but remember any **** fool can learn by experience. Don't be that fool.
PS: Even my T-Bird when warn at idle is 25 psi
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1500 is around 12 to 15
She's tired. Time to start saving up for a different engine. A good used engine probably makes more sense than a rebuild.
People reused cam bearings all the on the SBC. It was very common for them to still be in spec after a hundred thousand miles even if the engine had missed a lot of oil changes and was burning oil.
People use 20w-50 in Prius oil burners. They go another 100K miles that way
If you are willing to to take a gamble with some work involved just slam in a set of .001 under rod & mains. Do the rods& make sure they slide side to side after torquing. After each main installed make sure crank rolls around free. Install a Melling HV pump & pickup. This could buy a lot of time on a well used engine. If it should fail you are not a lot behind where you are now.
That's too low. This engine won't survive much longer with that pressure. It's already done for.
If that oil pressure is correct, the main bearings have too much clearance now, and thats where your oil pressure is leaking away. IF its not knocking, you might could remove the pan and check the main bearings. If they have not spun and scored the crank, you could try to roll in new bearings, but its iffy.
Not normally. They usually last the life of the engine
burbguy82
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If you have connected a mechanical gauge to verify the pressure.................over what others have said.............. it could be the screen in the pan being clogged, or the pump being bad or leaking. I am sure the scientists on here will disagree, but if the pickup screen is clogged and the oil passages are open, there will be substantially less pressure where ever you are measuring.
Worth checking out if you plan to keep the truck. I would run something thick in the meantime. 20w50, or some lucas.
Worth checking out if you plan to keep the truck. I would run something thick in the meantime. 20w50, or some lucas.
The OP said he ran it without oil for "a minute" so highly likely the bearings are shot.
Without machining the crank I think I would try standard size bearings instead of under sized ones. Too much risk of insufficient clearance on one or more journals.
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Run it with 20w-50, cover the oil pressure gauge with electrical tape and drive away. It might eventually die, it might not. If it doesn't 350 SBC's are everywhere, even today. Buy a used one, a rebuilt one, build one for cheap, but you have absolutely nothing to lose by running a heavier weight oil. Nothing.
Wisdom.
I would try a new oil pump first before rebuilding/replacing it. After my new oil pump in my 93 C1500 5.7l it builds better pressure again. Mine never got as low as yours but 8-10psi now it is around 15 now at idle. Easy job if 2wd but either way I would try it.
Also until then, running 15w40 or 20w50 will help.
Also until then, running 15w40 or 20w50 will help.
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