chevy vortec 350 delay in oil pressure on startup
09-20-2010, 12:14 AM
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chevy vortec 350 delay in oil pressure on startup hello i got a 1997 chevy 350 vortec seems to have a good 3 second delay in oil pressure when i start it up in the morning, i can hear the engine clatter until the oil psi goes up to its normal 45 psi on startup, it does this when the engine is a little warm too. the car has 160k on it, the oil is valvoline semi synthetic 10w40 oil, i was thinking it could be bad lifters that are bleeding off the oil too fast? but i could be wrong. what else could it be causing this problem? thanks for reading, i appreciate the help.
09-21-2010, 01:39 PM
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i have been using ac delco oil filters for a while and it never did this before. its a pretty big filter and i dont think i see a drainback valve on big filter like this
09-24-2010, 10:29 PM
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I was thinking of the acdelco pf58 and pf59, i think 58 had a drainback valve and 59 did not. but these were for the LS motors. if your not using those then never mind.
what filter are you using? pf2 or pf1218?
not sure if this could have an affect but the oil filter bypass valve could be stuck open. it is located in the block/filter mount where the oil filter screws onto the block (it is not in the oil filter). that may allow oil from the top of the motor to drain back down into the pan, basically defeating the purpose of the anti-drainback valve in the oil filter. what you can do after the motor has sit for a while, and is cold, is unscrew the oil filter. You should get a lot of oil drain out of the block, meaning it was being held up in the block by the antidrainback valve. if you unscrew the filter and the only oil that spills out is from in the filter then thats a good indication the top end is dry when you start, and it's taking that couple seconds or so which is reasonable for oil to make it to the lifters and rockers.
lifters bleeding off fast doesn't mean they're bad, many times lifters are supposed to bleed off fast. what's supposed to happen is oil pressure should be near immediate to the lifters because oil is held up in the top half by the filter antidrainback valve.
what filter are you using? pf2 or pf1218?
not sure if this could have an affect but the oil filter bypass valve could be stuck open. it is located in the block/filter mount where the oil filter screws onto the block (it is not in the oil filter). that may allow oil from the top of the motor to drain back down into the pan, basically defeating the purpose of the anti-drainback valve in the oil filter. what you can do after the motor has sit for a while, and is cold, is unscrew the oil filter. You should get a lot of oil drain out of the block, meaning it was being held up in the block by the antidrainback valve. if you unscrew the filter and the only oil that spills out is from in the filter then thats a good indication the top end is dry when you start, and it's taking that couple seconds or so which is reasonable for oil to make it to the lifters and rockers.
lifters bleeding off fast doesn't mean they're bad, many times lifters are supposed to bleed off fast. what's supposed to happen is oil pressure should be near immediate to the lifters because oil is held up in the top half by the filter antidrainback valve.
09-27-2010, 02:53 PM
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thanks for the reply, that is helpful. so if im not mistaken that part is called the oil filter adaptor correct? if that valve inside is bad then this is what would happen? btw its a PF1218 ac delco filter
