Hello,
I am writing to provide an update and conclusion on the issue I previously mentioned in the above post, in order to contribute to the collective knowledge on the topic of VarioCam issues in 996 Mezger engines (996TT/GT2/GT3).
Background: My Porsche 996TT was experiencing a rattling noise at idle and while driving, particularly when the VarioCam high-lift was activated. In addition, there was reduced power, a check engine light, and fault codes P0021/P0022/P1349/P1358 and Porsche Fault Code 325, indicating excessive cam deviation as per the Durametrics tool. The noise changed depending on oil pressure and temperature, and the issue showed similarities to what the BMW community encounters with some VANOS designs when they fail.
To get to the point, the Porsche 996TT/GT2/GT3 models utilize cam phasers similar to those in the BMW M62TU engines, typically found in late 1990s BMW 740i vehicles. These cam phasers are prone to aging and wear of the seals used in their construction. Thankfully, after establishing the connection between the cam phasers used in 996s with the Mezger engine and early BMW VANOS systems, I contacted Chris at Dr. Vanos in Austin, Texas (
https://drvanos.com). Chris was able to rebuilt my cam phasers, which resolved the issues.
Recommendation: If you own a 996 with a Mezger engine and you need to open the top end for any reason, I highly suggest having your cam phasers rebuilt. As these cars age, just like the BMWs, it is only a matter of time before the seals in the cam phasers wear out. Although I have heard of very few cases of this happening in 996TT/GT2/GT3 engines, I suspect we will see more occurrences as time goes on.
Here are the parts numbers this applies to:
996-105-051-73 - for the 996TT/GT2
996-105-051-93 - for the 996GT3
996-105-051-95 - for the 996GT3
I cannot confirm if there is a difference between the specific cam phasers used in these models, but based on the information I found, the cam phasers in the 996TT/GT2 can adjust the intake camshaft by 15 degrees, while the GT3 cam phasers provide an adjustment of 12.5 degrees.
Please feel free to reach out if you have any questions or comments.
Jeff