944Targa-fan

After changing my oil from 10W40 to 20W50 my car suddenly doesn't have any oil pressure anymore. First the car ran fine with the new oil, pressure was delayed but build up after a while. The next day the pressure didn't build up at all.

It is not a sender problem because the tappets are very noisy, and no oil is reaching the filter, with the filter removed and the engine running there is no flow of oil. I've checked the oil pump, oil cooler, OPRV, oil pick up tube and crankshaft bolt. All are fine. What's wrong with my car!?

ahofam123

How did you check the oprv? If you have the 1 piece oprv, you should replace the seal that fits at the end of it. If you have the three piece valve, you can lightly wetsand it (I used 2000 grit wetsanding paper) to clean off any imperfections. If you ever removed the oil cooler assembly, you might also have to use the alignment tool to realign the oprv opening.

944Targa-fan

I wet sanded the OPRV and replaced the guide tube in the engine block. After removing the cooler I aligned the OPRV opening. I,m sure it's not sticking.

The engine ran fine first, the next day no more oil pressure. This happened after I changed the oil from 10W40 to 20W50. What could have been damaged after the oil change?

951Tom

Check to see if the crank bolt came loose. Needs to be tight or you'll get nothing.

Rob

Did you do all this work at the same time as the oil change, or was the OPRV/cooler done at some prior date?

If it was done at the same time, you probably need to prime the system. This is done by pouring oil down the center of the oil filter mount, removing the plugs and DME relay, and cranking away in 15~20 second intervals until oil pressure is achieved.

Also, what kind of oil filter did you use. I've read some don't some don't have the check valve inside them to keep them full. When started, this could basically de-prime the system. Once you have air in the system, it can take a while to get the system primed.

944ZEN

Sound exactly as when i did a oil pan seal change, tok 3 days before there was no pessure at all. Tried the prime thing it helped for 2 days, but the pressure was allways 20-30 sec to buildup in the morning, getting longer and longer, until the 3'rd time i clenaed the oprv with 1500 grid wet sanding.

But try seek for Oprv & slow oilpressure, we have had a lot off posting regarding this.

I agree with the above it's one off 3 thing.

1) Air in oil system = Prime it.
2) Misalignment off oil cooler = Correct
3) OPRV sticking = Cleaning or 2)

good luck.

944Targa-fan

The cleaning and aligning of the OPRV was done after the oil change. I will try to prime the system, how much oil should I pour down the oil filter hole?

944ZEN

I put about 0,3 Litre (dont know what it is in US spec).

keith

check the torque on the crank bolt.

Don't run it anymore until you find something.

Kirby2

If you changed from a parafin based oil to synthetic, the pressure sending unit is notorious for sticking.

944Targa-fan

It's not the pressure sending unit, the lifters are making terrible noise, so the oil is not reaching them. When the engine is running, I can take of the oil filter, no oil is reaching it.

I torqued the crankshaft bolt to 210 Nm so that should be okay, I hope priming the oil system will solve the problem. When changing the oil to 20W50 I used a Mahle filter, maybe the non return valve wasn't working and let air in the system. Is this a possibility?