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Mezger rattle on start-up. Solved and relieved.

drabux

Well-known member
Joined
1 Oct 2014
Messages
409
Since my last oil change, on a cold start up there's been an awful rattle, sounding very much like depressurised cam lifters. I considered a top end strip to fix the lifter problem but then read that this problem can be caused by a worn o ring on the oil filter.

There are two o rings and, during an oil change only the large one is usually replaced. But a worn smaller o ring can cause oil pressure to be lost when the engine is off.

I replaced the o ring yesterday and what relief to find no clatter at start up. I've spent months worrying about this problem!

Hope this may be of use to someone else.
Alan
 
drabux said:
Since my last oil change, on a cold start up there's been an awful rattle, sounding very much like depressurised cam lifters. I considered a top end strip to fix the lifter problem but then read that this problem can be caused by a worn o ring on the oil filter.

There are two o rings and, during an oil change only the large one is usually replaced. But a worn smaller o ring can cause oil pressure to be lost when the engine is off.

I replaced the o ring yesterday and what relief to find no clatter at start up. I've spent months worrying about this problem!

Hope this may be of use to someone else.
Alan

Great news thanks for the info!
 
Interesting bit of information. Do you have a link to the parts diagram or even the part number?


drabux said:
Since my last oil change, on a cold start up there's been an awful rattle, sounding very much like depressurised cam lifters. I considered a top end strip to fix the lifter problem but then read that this problem can be caused by a worn o ring on the oil filter.

There are two o rings and, during an oil change only the large one is usually replaced. But a worn smaller o ring can cause oil pressure to be lost when the engine is off.

I replaced the o ring yesterday and what relief to find no clatter at start up. I've spent months worrying about this problem!

Hope this may be of use to someone else.
Alan
 
drabux said:
Since my last oil change, on a cold start up there's been an awful rattle, sounding very much like depressurised cam lifters. I considered a top end strip to fix the lifter problem but then read that this problem can be caused by a worn o ring on the oil filter.

There are two o rings and, during an oil change only the large one is usually replaced. But a worn smaller o ring can cause oil pressure to be lost when the engine is off.

I replaced the o ring yesterday and what relief to find no clatter at start up. I've spent months worrying about this problem!

Hope this may be of use to someone else.
Alan

Excellent piece of detective work and this must be a relief , no more sleepless nights then !!

Good work and surprising fact to come out of this is .... Why is the o ring not replaced at the change ?
 
drabux said:
Since my last oil change, on a cold start up there's been an awful rattle, sounding very much like depressurised cam lifters. I considered a top end strip to fix the lifter problem but then read that this problem can be caused by a worn o ring on the oil filter.

There are two o rings and, during an oil change only the large one is usually replaced. But a worn smaller o ring can cause oil pressure to be lost when the engine is off.

I replaced the o ring yesterday and what relief to find no clatter at start up. I've spent months worrying about this problem!

Hope this may be of use to someone else.
Alan

Excellent piece of detective work and this must be a relief , no more sleepless nights then !!

Good work and surprising fact to come out of this is .... Why is the o ring not replaced at the change ?
 
e92 said:
Thanks. Does it sound a little like the cold start in this video? (9 seconds to 11 seconds in the video)

https://www.youtube.com/watch?v=hY4uqd7vzGA



drabux said:
This is the culprit. Apparently many Indys and some OPCs do not replace it as a matter of course. https://www.design911.co.uk/fu/prod126866/Oil-Filler-O-ring-Porsche-996-Turbo-GT3---997-Turbo-GT3/

I think this may be the same sound. It's hard to tell because of the microphone but it certainly lasts for about the same amount of time. The noise happens while oil pressure is being built up.

Among OPCs, apparently, this is a known issue and culprit but I cannot fathom why it is not widely known. I have read about many Megzer engines with cold start clatter and my suspicion is that this silly o ring would fix a fair proportion of them.
 
I've listened again and that's the noise. Yes.

If you know the history of the car, the question to ask is whether the noise started after an oil change.
 
My car started making that noise but only if I had left it a few days. I did some research and watched videos like the one I posted which showed most made that noise as the oil pressure built up. All the other forums said it was normal and that these cars were designed to be used daily and there was nothing I could do about it. Good job finding out what the issue could be, I will definitely be ordering the o ring. Once again thanks a lot



drabux said:
e92 said:
Thanks. Does it sound a little like the cold start in this video? (9 seconds to 11 seconds in the video)

https://www.youtube.com/watch?v=. hY4uqd7vzGA



drabux said:
This is the culprit. Apparently many Indys and some OPCs do not replace it as a matter of course. https://www.design911.co.uk/fu/prod126866/Oil-Filler-O-ring-Porsche-996-Turbo-GT3---997-Turbo-GT3/

I think this may be the same sound. It's hard to tell because of the microphone but it certainly lasts for about the same amount of time. The noise happens while oil pressure is being built up.

Among OPCs, apparently, this is a known issue and culprit but I cannot fathom why it is not widely known. I have read about many Megzer engines with cold start clatter and my suspicion is that this silly o ring would fix a fair proportion of them.
 
thanks for this :thumb:

I've had this on mine for the last 2 years. It's really bugged me that I couldn't resolve it.

Car is going in for a service in a couple of weeks so 'O' ring now ordered. Lets see if it sorts it
 
9 seconds to 11 seconds in the video

Intentional with that timing?

I think so!!

:thumb:
 
Just had a look in the garage & it appears the filter only comes with the large O ring in the pack.

Also, looking at the prices from D911, they are at least double the price of an OPC for the sump plug seals, so the O ring will likely be the same...
 

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