jeebus31

Howdy.

My 997.1TT has the annoying panzer-like rattle on startup after sitting for a while. Today, since I hadn't driven it in a week, I video taped the startup to demonstrate the noise, and actually only on review of the video did I notice it very briefly flashed the "oil pressure too low" signal on the dash. It's not perfectly in focus, so I apologize for that. The oil pressure pegged to 5 like it always does, and then it slowly dropped to normal idle as the engine warmed up. Oil level is normal and there are no leaks/drips. I had previously replaced the tiny O-ring on the oil filter housing thinking that might help the "problem" but the car is no different before/after. The oil filter housing was bone dry when I replaced the O-ring. I don't really have any other issues with the car, once warm it drives fine, and it definitely likes to be daily driven. When I drive it frequently, I don't get nearly as many of the loud rattle starts. The only other thing I get every once in a while are some rough idle cold starts and SAI/rich idle codes that clear and don't come back especially if driven more often.

Has anyone had anything like this, and what should I be checking/diagnosing? Thanks!

997TTEQNY

My car did this exact same thing last year. Not all of the time, but some of the time. I dont drive it much so it went days without a cold start.

I kept an eye on it, and nothing really came of it.

I got an oil change this year and its gone

My car always has valve train noise upon cold start. Ive been told this is normal.

lflouie

The fact filter housing was "bone dry" is a clue to the fact that the oil is draining back into the sump. This will result in an instantaneous low oil pressure and likely be the cause of the "rattle" at startup.

You indicated recently replacing the oil o-ring. Did you have one before? Is the new one a Porsche part or another brand?

Fyi, when I pull the filter housing it always has measureable oil inside.

jeebus31

The new o-ring was genuine Porsche rubber.

What else could cause the top end to drain over a short period of time?

jeebus31

https://rennlist.com/forums/996-turbo-forum/1005163-chain-rattle-on-startup.html

Just read through that thread and gained some valuable information. Seems like it's "normal?" Will this noise cause rapid wear of the chain guides? The insanely hot weather we've had recently seems to exacerbate the frequency of these types of starts.

saabin

Yikes, that doesn't sound good at all. I've never heard such noises on startup, no matter how long it sits. I would hazard to say "not normal" but not sure what the issue could be.. maybe one of the scavenge//oil pumps is bad? I recall reading somewhere when I got my car that this engine something like 9 oil pumps..

jeebus31

Yeah it definitely sounds concerning, but now that I'm searching around RL and 6spd it appears that there are a bunch of threads about this and they all seem to have similar content. Here is a post with a sound clip of a cold start 996tt that sounds like mine https://rennlist.com/forums/996-turb...l#post14450456

In that thread there is a recommendation to pull the fuel pump fuse and crank the car to build up oil pressure and then start the car if it sits for a while.

I think if one of the oil pumps was bad, I would have more symptoms than just at startup? Lots to learn about this car...

Kevin

What oil weight and brand are you running.

jeebus31

Motul X-cess 8100 5W40.

Kevin

I'd dump the Motul 8100 and refill with Motul 5W50 Sport

If you want to go to the dark side.. I am running Redline>>it does a nice job making the chain rattle quiet down.

Cosmo Kramer

Mine has never done that I run the same oil.

Kevin: Does Motul Sport 5w50 have the A40 certification ?

jeebus31

Hmm, I must have seen you or someone else recommend this at some point because I have two jugs of this somewhere in my house waiting for my next oil change:

TT.BRN

Sounds to me like a bad chain tensioner .....

Kevin

No, Motul didn't pay to have the oil A40 cert.. 300V doesn't have the A40 cert.

The Sport Ester is a better oil (formulation/base stock) vs 8100...

I say this every oil thread.. Send in your oil for testing. Use a oil that reduces the wear metals as miles and age rack up!

ShatterPoints

I did a blend of 0w-40 and 5w-50 as I found you recommended in another thread. I am in TX so the heat is definitely up there. I went with a 50/50 blend as we are transitioning into fall and winter, during summer would it be fine to run full 5w50? I also use redline and drain every 4000-4500.