sgla

Hi All,

Got a PPI done on a 2002 Porsche Carrera 4S with a Tiptronic transmission (776.2) from a reputed tech. PPI noted that "During the test drive noticed a drive line noise that starts around 50 miles per hour that changes with throttle input. Something in the drive line is failing,"

Talking to the tech he said that while cruising around 50-60 mph, trying to feather the throttle results in a clanking noise similar to when a dual-weight flywheel is replaced with a single-weight flywheel in a stick-shift car. Discussed everything from transmission mounts to a remap of the TCU, but couldn't come up with a solid theory.

Not looking to walk into a transmission grenade, so looking for some advice,

Thanks,

SG

theprf

Likely culprit is the rubber donut on the front driveshaft, which is easy to check. Other possibilities could be CV joints, wheel bearings, tires, and I would put the transmission last in line. Without hearing the noise it's difficult to locate it to a specific component.

sgla

Thanks prf for the response!

The tech was unable to get a recording of the sound while driving the vehicle down the highway. CV joints were replaced in 2018, the noise happens when driving straight down the highway and gets louder with throttle application, so could be the wheel bearings. Tires also seem fine (recently balanced), but good point on the rubber donut on the front driveshaft, I will ask the tech if they saw anything there. I would also agree that it's unlikely that it's the transmission since these 996.2 tiptronics have the reputation of being pretty hearty, but don't want to rule anything out.

theprf

I wouldn't be so quick to thumbs up the tires, when they're old they can get very loud.

sgla

Quickly went back and double checked, tires are Michelin Pilot Sport PS2 (N3) from 2017/2018 and seem in decent condition.

theprf

It's tough to diagnose noise while driving and even harder on a forum. How familiar is the tech with 996's?
Anyway some other noise sources could be serp belt, A/C compressor bearing, serp belt idlers, induction leaks, motor mounts, trans mount, things not installed correctly, etc.
There's a lot of stuff back there! If someone's repaired something and omitted a bolt or not routed a hose properly it can transmit noise. Saggy motor mounts are very common and can let the power unit move around, perhaps something's touching occasionally.

cdk4219

inner cv joint failure comes to mind