superloaf

Started my car today and oil pressure took a long time to come up and before it did, i heard some tappet noise. I've never experienced this before and this was after the car had already been warmed up and driven around a few miles. I checked oil and it was a little low so i topped it up and then let it sit for a few hours but then when starting again, it did the same thing but this time with a little bit of metal clicking as soon as the starter began moving the engine but before any hint of it catching. Once running, it seems fine with no further noise. And i just finished a big engine job where I did timing belts, complete front engine reseal, lower balance shaft housing bearings and reseal, oil cooler housing reseal, oil pressure relief valve rebuild (new o-rings).

The only thing i can think of is a possible loosening of crankshaft bolt or maybe OPRV problems. Oil pressure has been fine since i did the work which has been about 500 miles ago so not sure if OPRV would cause a problem at this point. The oil pump sleeve was replaced and even a new bolt was used. I'll check the crank bolt tomorrow but just wanted to see what other problem it could be?

Many thanks in advance.

Humboldtgrin

superloaf

Oil pick up O ring was replaced two years ago. And a wouldn't a cracked pick up tube cause oil pressure problems while running and driving, not just on start up?

Humboldtgrin

Droops83

Did you have the cam tower off as part of this repair?

superloaf

Droops83

There is an oil pressure check valve at the lower rear corner corner of the cylinder head (near cylinder #4) that can cause similar issues if it is missing or jammed . . . . to remove it requires drilling and tapping a press-fit cap, so it is unlikely that it fell out with the head in situ while doing the cam tower.

I suppose it is possible that the crank bolt isn't torqued enough, but I would think that you would have low oil pressure at all times if that were the case . . . . certainly worth checking, though.

I would also check the OPRV to cover all of your bases. I assume that you used the proper alignment tool . . . .

superloaf

thanks for the possible things to check for. It seems to not be happening now so I'm keeping an eye out for the time being. I checked the crank nut as best i could without locking the flywheel which i admit isn't much of a check but it's not completely loose.
When I did the OPRV the internal o-ring didn't fit properly (it was too big and loose; and it was a Porsche dealer part so not sure why it was not a proper fit) and basically was sliced in two when assembling the two parts of the OPRV together so I had to use a generic o-ring that fit properly. However, this is obviously a problematic solution. I did use a nitrile ring so hopefully it won't disintegrate.
And i did use the OPRV alignment tool when installing the oil cooler housing so that shouldn't be an issue.

Geez, the more i work on this car i must admit my high regard for Porsche engineers becomes diminished as i just don't know what they were thinking when they design some of these parts. Even closer to today, they do dumb things such as the intermediate bearing fiasco on the 996's. Such as easy and inexpensive solution to these problems could have been simply designed into the engines and yet they fail to do so, over and over. Oh well....