M54 playing the didgeridoo?

[Benji]

Im facing a bit of a weird issue with my M54B30, it has taken up the didge. Each time I start the car, the red oil pressure light stays on for about 4 sec, I get loud lifter tick and this didge noise coming from the motor. The lifter tick goes away as soon as this didge noise subdues after about 10 sec. Upon further investigation (screwdriver to the ear - poking around under bonnet) the noise is found to be coming from the oil filter housing.

These symptoms would suggest a bad oil check valve in the OFH, the logic is that the oil drains out of the OFH and the didge noise and lack of oil pressure could be the OFH filling up with oil on startup. However, I have checked this - even after standing for a week, there is oil in the OFH when you remove the filter. The oil drains out once the filter is removed, but only to the filter level - the "sump" remains with oil indicating a good check valve. Weirdly, after the noise has "subdued" it is still audible - even over my bad powersteering pump.

What could be making that noise? Im leaning towards oil pump? Maybe the sprocket on the pump has come loose? Maybe the pump is failing? I have never had the oil pressure light come on in normal driving, but I somehow have a suspicion the oil pressure isnt what it should be

 

[Kyle]

You could probably hook up ISTA and monitor oil pressures to see if you have an issue with the pump?

 

[Teezoh]

Loose oil pump nut, sprocket, or oil pump relief valve could be sticking?

 

[Gordvisr]

How long do you own this ? was regular services done ? One other observation i had on a different car was the oil suction cup, was heavily blocked by pieces of engine sealant, old oil carbon and so forth, it resulted in a bearing knock too. I will rather not drive it until the oil pressure loss issue is sorted, those lights( oil pressure ) are usually like a home pregnancy test. if it came on there is a problem.

 

[Benji]

You could probably hook up ISTA and monitor oil pressures to see if you have an issue with the pump?

These motors dont have oil pressure sensors, just a switch

Loose oil pump nut, sprocket, or oil pump relief valve could be sticking?

I am also suspecting something with the oil pump, will pull the sump next time I do a service, car has been making this noise since I got it, just starting to work up the courage to investigate it