Hey guys...

I've poked around a lot of the threads on various forums (6speed, renn, pistonheads, etc.) regarding the constant, ambient "rattle" that's apparently common in 996TT engines.

I'm referring to the "play" tolerance of the Intermediate Shaft (IMS) and/or its subsequent bearing assembly.

The general consensus is that it's likely within "tolerance", but that it's certainly not a badge of engineering achievement on Porsche's part.

From what I've been able to gather, this is kind of related to the symptoms that plagued the early model 996 NA 3.4 engines. Basically the 996TT/GT2/GT3 engines were largely strengthened and used more robust internals than the NA engines.

But, of course, there's some controversy about all that as well.

Bottom line, movement, or "play" or whatever is going to lead to excessive wear, which can lead to engine failure.

I just can't help but feel a bit depressed listening to my car's rattle... it's like I have a car with terminal cancer or something. Sure, there's probably a number of years left.

But someday... the "big one" is coming.

Ugh.

Maybe I'm missing something?

You guys know if there a pre-emptive fix or solution of any kind?

Cheers

-Chris

 

I have the rattle as well, and I've asked the guys at RUF every time I'm in for service if it's normal. Every time they tell me my car is fine, the rattle is par for the course with turbos, and some are just a little more noticeable than others.

When I asked if there was anything I could do to eliminate the rattle, Hans said sure - tear the engine apart and rebuild it. So - I'm okay with a little rattle.

 

I will have to find the thread on this, but their was a guy that tore his engine apart for the rattle. He found that the bearings were worn, but not excessivly enough to cause the rattle. The gear lash was within specs too. He fixed it be replacing the IMS. My guess is it has something to do with the gears and how close their tolerance is, but the manual seems to clearly define the tolerances. And being within tolerance can still cause noise. I have not heard of the normal idle clattering to cause further engine damage. I know people who have the normal clatter and track their cars without issues. I would talk to an engine builder that knows these engines well and see what they say. It sounds to be more of a nuisance than anything else.

 

Thanks for the input VAG and leftlane - makes me feel a little better :-)

Hopefully my well maintained rattlebox will last a few years down the road...

-Chris

 

There are some guys back east doing a preventive repair. Bearing is upgraded as is the support. Special tools needed to do it, so you'd need a good indy to do it. One of the shops I use has done it a number of times, but it's too early to tell if it's a permanent fix. I have seen the results of a failure tho and it ain't pretty. The cars that haven't had problems are those who have been run fairly hard: track days, etc. Seems to get an oil film up around the bearing and help its longevity.

I was hoping the GT1 block was immune to this fricking design flaw.
http://www.lnengineering.com/ims.html

 

great thread topic. good read on the link... but was seriously hoping not to have to take preventative action on this, that this engine's "life span" was designed so that it's meant to be rebuilt, before the IMS fails.

 

mine rattles a little bit at idle but I am used to it.

 

Are you talking about the rattle under light acceleration and low speeds? I get that sometimes- never really thought it was an issue....i'm starting to reconsider that now

 

Can't hear mine cause my wife never stops talking

 

Your exhaust is not loud enough I can't hear any rattles at all!

 

We all have the rattle.

 

+ 1 and it is normal

 

normal rattle, i would worry if it didn't rattle. i would think there is something wrong with the car....

 

If it goes away when you rev off idle, it's supposedly normal...

 

+1..