Oil pump draining down - any clues?
Discussion
Hi all,
Oil pump is de-priming itself, meaning that on cold start its got zip oil pressure! Priming tool in drill on the oil pump shaft, whiz it round, nothing, not even a hint of resistance or pressure on the gauge. Nowt.
Both the oil light and pressure gauge are showing zero, and when i draw oil up from the sump using my big oil syringe in the filter feed hose, then prime with a drill, it primes fine, and then starts up and the pressure is right there, up to 40PSI and all is in rude health.
Soooooo, the light and gauge ARE working. Oil pressure seems good. I've got it on 5W-50 fully synthetic oil, and it runs at about 30-50PSI under most conditions. I've noticed the oil pressure does drop to about 10PSI on hot idle, and the light sometimes flickers on at idle, but the moment the engine revs rise, the pressure increases immediately.
It did run higher oil pressure when I was using 15W-50, I must admit...
So, the drain down problem. I've had the sump off and the pickup is fine and tightly attached with a gasket. The filter, as always, is a Fram PH2821a with the anti-drainback valve in it.
Thing is, its absolutely fine until cold start, and has been absolutely fine even on cold start until today... It had a good run out on Saturday, back in the garage, and today no oil pressure.
Any clues? I'm about to strip the front of the engine back to the block and inspect the whole lot.
Is de-priming a sign of an ailing pump? My guess is that air must be leaking in somewhere to allow oil to drain out and leave the pump high and dry.
Any clues would be appreciated.
Ed.
Oil pump is de-priming itself, meaning that on cold start its got zip oil pressure! Priming tool in drill on the oil pump shaft, whiz it round, nothing, not even a hint of resistance or pressure on the gauge. Nowt.
Both the oil light and pressure gauge are showing zero, and when i draw oil up from the sump using my big oil syringe in the filter feed hose, then prime with a drill, it primes fine, and then starts up and the pressure is right there, up to 40PSI and all is in rude health.
Soooooo, the light and gauge ARE working. Oil pressure seems good. I've got it on 5W-50 fully synthetic oil, and it runs at about 30-50PSI under most conditions. I've noticed the oil pressure does drop to about 10PSI on hot idle, and the light sometimes flickers on at idle, but the moment the engine revs rise, the pressure increases immediately.
It did run higher oil pressure when I was using 15W-50, I must admit...
So, the drain down problem. I've had the sump off and the pickup is fine and tightly attached with a gasket. The filter, as always, is a Fram PH2821a with the anti-drainback valve in it.
Thing is, its absolutely fine until cold start, and has been absolutely fine even on cold start until today... It had a good run out on Saturday, back in the garage, and today no oil pressure.
Any clues? I'm about to strip the front of the engine back to the block and inspect the whole lot.
Is de-priming a sign of an ailing pump? My guess is that air must be leaking in somewhere to allow oil to drain out and leave the pump high and dry.
Any clues would be appreciated.
Ed.
Could you initially just drop the bottom cover off the oil pump?
I'm thinking a slight gasket leak on the suction side of the pump cogs might let it drain back down (by letting air in) but wouldn't necessarily show as an oil leak?
I guess the same applies to the front cover gasket on the oil route to the pump.
I'd also try another filter just in case.
Your plan to be honest sounds like a good one to take the front cover off.
I'm thinking a slight gasket leak on the suction side of the pump cogs might let it drain back down (by letting air in) but wouldn't necessarily show as an oil leak?
I guess the same applies to the front cover gasket on the oil route to the pump.
I'd also try another filter just in case.
Your plan to be honest sounds like a good one to take the front cover off.
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