We don't just build GT3 engines here... but this is seriously the stuff that keeps James awake at night! If any of you guys also have either a 996 or 997 GT1 based Twin Turbo and are experiencing more engine vibration/noise than you'd think was normal we've unfortunately seen our fair share of this nasty symptom. It's not the same IMS failure you here/read about on the M96/97 engines (that is more common too).


How many degrees of play in that crank shaft?!?! At first you won't even get any check engine lights/codes either. This type of set up is in all the 996/997TT GT1 engines but luckily NOT I repeat NOT in our GT3s- phew. One has to wonder why... The only other thing I can say is of the turbo engines we've seen with this failure there seems to be a correlation of a light weight flywheel into play as well which _could_ be exacerbate the problem due to additional transmitted vibration.

To check for this if you're worried you can rotate the crank shaft back and forth and it it feels loose at all then the next step is to remove the driver's side upper cam cover and observe the relation between the crank shaft movement and the cam shaft movement. Obviously you want to nip this in the bud before it gets bad and leads to a total catastrophic failure.

The noise is most noticeable at idle and when gently increasing the revs to 2000 and then releasing the throttle pedal. It's kind of frustrating that the Turbos don't have the same design as the GT3 but there you have it (or hopefully not!).

 

Could you compensate for a LWFW by using a lighter crank pulley on the other end? Newbie question. Thanks for your time.

 

I wonder what the part looks like on a GT2RS, which uses a LWFW.

 

Is the failure related to mileage or does it occur regardless of wear ?

 

It's certainly happening on cars with over 40k at least... But it's possible the LWF's are accelerating the issue....
I have a hunch on the RS they're using the same as on the GT3
I don't know that it'd make a huge difference... just a sloppy design really