Edovol

Hello, I'm new to the forum!
I have a 997 tt mk1 which gives me a lot of satisfaction. Still, quite often the quality of the P service here in Paris is not ideal.
I'm sharing with you the latest problem I had as it ended up with an interesting learning.

After bringing in the car for a standard maintenance (oli, oil filter, etc) the car started to make a very clunky noise (like a loose distribution chain!) at start-up. The issue was only happening for 1-2 seconds just after firing up the engine (while the oil pressure was building up) and only if the car had been sitting for at least 3-4 days in the garage. No noise in other conditions.

I was a bit worried and I checked at Porsche service, but the guys had no idea on possible cause/solution, so I started investigating a bit. I checked out the oil filter box and I realized there are actually 2 seals on the cap and that the small one (a tiny O-ring) was not replaced during the service.
Surprisingly at Porsche they normally only replace the big one, BUT NOT the small one. I supposed the failure of this o-ring may let the oil flow slowly away from the upper part of the oil circuit and I thought it may have been the cause of the issue (I found a similar case as well on the internet).
Went back to the garage, got the o-ring changed and .....the noise went away.

In case you have a similar issue, have a look at the oil cap it and you may resolve the problem in a quick and inexpensive way.

estrellajon

I can't picture this oil filter box . You mean the oil filter housing? The seals on the cap?

Edovol

Yes, the housing! The seals are on the cap an you have:
Big one: around the exterior border (actually avoiding the oil to get out from the box)
Small one: at the end of the central 'pin' of the cap

estrellajon

Got it. Yes . Always change these. They shrink and upon reinstall, they won't seal the same

Jako

I've got the same intermittent situation. The conditions for that to happen are, cold temperature and car left sitting for days. Then on first fired up, I have the same rattling for 1-2 seconds.

I read on another post it was due to some flap in the exhaust getting stuck.

Edovol

...I thought the same at the beginning, but it was not the exhaust in my case...

Jean-marc Rif

Same sound here, was told by Porsche center that it is was nothing to worry about. Weirdly heard the same noise for the same amount of time on a loaned Mercedes C 180 upon cold start up.

TT-911

Indeed a known problem if oil filter is changed incorrectly. You need to replace all gaskets (and seat them correctly).
It's important the other posters address this asap, it's not good to regularly start your engine without oil pressure.

Edovol

...I fear that the guys at Porsche are briefed to answer 'nothing to worry about' whenever they are asked a question on which they are not prepared...

Edovol

...and, by the way, I finally had to change the entire cap as apparently it takes a lot of time to gat the replacement O-ring (probably it is too cheap)

heliflyer

Design911 in UK always have these O rings in stock

labdag

I had the cold start up rattle for 2sec and on occasions i would get "low oil pressure" warning which also disappear when pressure builds up. the oil pressure was taking 2 or 3 sec to build up. I changed oil tank return check valve and the small O-Ring which Edovol mentioned. Its been a week and NO rattle on cold start. I believe the correct small O-Ring is the key. I has to be seated properly to ensure no oil leak out of the filter housing which ensures quick oil pressure building up. Also ensure you have 25NM torque on oil filter housing.
I recall this from my 300TD days. See video:




Regarding the oil tank check valve: I bought a new one which, to me, looks exactly the same of the old one EXECPT it had a "Blue" dot on it which is supposed to be the upgrade part. pics of the old one:

ble2011

Quadcammer

Its pretty hard to miss. Its at the tip of the center rod in the filter cap

therock88

Here ya go....