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AV996TT

intermediate shaft failure

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I posted over at the 6speed forum about a ticking noise from my engine, thought I'd get some feedback from over here as well. I've pretty much just chalked it up to normal engine noise from reading some posts here, but since my extended warranty was coming up, I decided to take it in to the dealer to get a last look. I was told that the noise is louder than most turbos they've heard and that it would require them to drop the engine to diagnose. They said they will remove the oil pump and check that first, as that is where they think the most sound is the loudest, but I believe the suspect something else inside the motor. They mentioned maybe a camgear or something. Since, it is an extended warranty, I am stuck with the labor cost of pulling the motor in case nothing is broken. If they find something then I'm ok and the extended warranty will hopefully cover the labor and parts. Otherwise, I'm out $5000 just to pull the motor (est. 40 hrs labor) . Does that seem excessive?? Anyway, my saving grace here is that if there is something, then I have an extended warranty I've noticed another previous post that seems to be exactly what my diagnoses has been and it was an intermediate shaft failure. I also had the chain tensioners replaced in response to this problem.

Here is a link to some vids of my car when you hear the sound:

and when you don't:

seems the noise is not present when the motor is cold. When it warms up then it gets pretty loud.

Odd since you would think the the engine would tighten up when it got hot. So, I think that eliminates chain slapping.

Here is a link to cpu77's problem that seems to be very similar to mine.

http://www.6speedonline.com/forums/996-tur...thanks-umw.html

any of you know what the difference is between a gt2 motor and TT motor? is it less prone to this type of failure? I thought they were both the same split case design.

Edited by AV996TT

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Intermediate shaft(or bearing) failure is a known failure with the M96 engine. The TT uses the aircooled split- case design with the 8 main bearing crank. It is pretty much the same as the GT-2. And is very reliable. The TT sounds you posted are identical to the many air-cooled (normally aspirated)911s I have owned over the years. And which have the same basic intermediate shaft design as your TT.

It is interesting that the chain tensioners were replaced- the chain will rattle if the tensioner is collapsed - but usually only when cold.

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You asked about 40 hours to pull and reinstall engine. That is excessive. I just went through this at my Porsche dealer and it took them 10 hours out and 10 hours in.

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You asked about 40 hours to remove and reinstall the engine. I just went though this at my Porsche dealer and he charged me 10 hours remove and 10 hours reinstall.

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40 hours seems excessive to me as a well. But I know from talking to the tech that is replacing the engine on my 996 C2 that a pulling a Turbo engine is a lot more work. Twice the time from what he said (which I guess would equate to 40 hours.)

Just passing along what I was told.

Edited by phillipj

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Whoa! Time out here!

AV996TT - your profile says 2001 996TT.

The 996TT does not have an intermediate shaft failures that I am aware of.

The engine design is much different than that used in the 986 and 996 normally aspirated engines (M96 engines).

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AV996TT - your profile says 2001 996TT.

The 996TT does not have an intermediate shaft failures that I am aware of.

Oh yes it does! I know it first hand, having had one last August. A friend of mine had it too about 1.5 year ago, and there are quite a few exemples on the net too.

I'm in a bit of a rush right now, but will post more details later.

And yes, 40h just to pull the engine out is way too much.

Edited by pierre

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The intermediate shaft build in the Turbo and GT2/3 is a lot smaller and shorter, more important is the much better bearing instead of the M96 half floated large shaft which Loren indicates.

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The intermediate shaft build in the Turbo and GT2/3 is a lot smaller and shorter, more important is the much better bearing instead of the M96 half floated large shaft which Loren indicates.

That's a relief to hear. I should hear more from the dealer on Monday or Tuesday. Hopefully, it's something else less major.

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That's a relief to hear. I should hear more from the dealer on Monday or Tuesday. Hopefully, it's something else less major.

Any news from your shop?

BTW, here a few examples of intermediate shaft failures:

- A friend from Sweden wrote this:

I just faxed you a copy of the repair receipt for my 2001 996 Turbo

(WP0ZZZ99xxxxxxxxxx). The car had 95000 km at the time. The engine had to

be removed, opened and lose parts in the intermediate shaft (Swedish:

Mellanaxel) had to be tightened. I was just lucky that the screws did

not fall off and damage the engine.

- in UK

http://www.rennteam.com/showflat.php?Cat=0...true#Post186661

http://forums.rennlist.com/rennforums/show...ad.php?t=249775

- in Ohio

http://forums.rennlist.com/rennforums/show...ad.php?t=355517

http://www.6speedonline.com/forums/996-tur...iate-shaft.html

http://www.6speedonline.com/forums/996-tur...thanks-umw.html

- UK again:

http://www.renntech.org/forums/index.php?s...c=8295&st=0

- CA

http://www.6speedonline.com/forums/996-tur...n-noise.html#12

- 996 GT2 too?

http://forums.rennlist.com/rennforums/show...7&page=2#27

- people become unsecure

http://www.pca.org/tech/tech_qa_question.a...F-2D309C7DB7B8}

http://www.renntech.org/forums/index.php?s...=22586&st=0

- 997 TT too?

http://www.6speedonline.com/forums/997-tur...und-engine.html

http://www.6speedonline.com/forums/997-tur...d-engine.html#7

About the 997 TT: a very reliable source told me they've found the very same potential problem on at least 2 997 TT engines. This shows the issue hasn't been fixed by Porsche and still might happen on any current generation Turbo.

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Some of those examples are repeats - or the same people posting on multiple boards.

And, some are 996 Carrera's - which are not even the same engine.

I think they can and do occur but not very often (especially in a factory stock engine). MHO.

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Some of those examples are repeats - or the same people posting on multiple boards.

And, some are 996 Carrera's - which are not even the same engine.

I think they can and do occur but not very often (especially in a factory stock engine). MHO.

Sure, these are only a few examples I found browsing the forums. It definitely doesn't show the complete picture. Again, just a few examples.

And I agree, this doesn't occur very often. But the issue is for real, and when it happens, it causes a serious engine damage. I don't understand why Porsche hasn't at least fixed it on the new generation engines... Besides, whether the engine has been tuned or still is bone stock is not relevant.

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The heads were removed on Thursday and some scoring was noticed on the passenger side camshafts and lifters. They stated possible oil starvation on that side , as the driver side cams showed no sign of damage. The crankcase was split on Friday and they noticed the intermediate shaft bearing had failed and the bearing surface toward the other end of the intermediate shaft was really worn to where you could see a copper like color. The dealer is going to write up their findings and submit to my warranty company. I should know what the decision is by the end of next week.

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any news on this??

I must admite when i got my 03 996TT a few months back it did scare me to hear a super car sounding like a tractor when at idle... I searched on here and found no end of it's normal and not a problem.. now your getting me worried... my noise is no were near as bad as yours sounds but still a little clanky... my warrenty only lasts for 6 months so now i'm wondering if it's worth spending the £1500 on an extended 12 months just in case... it's catch 22 spend the money and nothing will happen money lost... dont spend the money and i can bet as soon as the time ticks to no warrenty time my engine willl un-mount itself and walk off in a big bag... sods law... GRRRR

hope your gets fixed all ok.. I would love to hear what it sounds like after you have had it sorted out.. if you can do that that would be great....

O by the way can you not remove those horrible lumps of plastic each side of your rear plate?? i'm in the uk and i know the plates are diffrent sizes but those humps make the back end look... well ....humpy...or is it law over there to have them? sorry off topic but just wondering...

Edited by atomicveilside

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Take note that Turbo and GT2/3 engines makes more noise ( by construction ) on the rear side than Carrera's.

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Ah the old intemediate shaft failure! Makes a guy want to cry! I have a brand new GT2 motor and it still clanks:) Not like it was before the swap though. The whole experience really made me HATE porsche! At least Porsche gave me the full treatment. Without lube. Call me if you like! I actually got alot of help from Kevin at UMW. Super guy! Nothing like blowing $80k on a used car with 13k miles that develops a serious issue at 14k!

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Just so everyone is clear, these two pic's show the intermediate shaft for the TT/GT3 (and all air cooled 6cyl Porsche's for the last 60 years) and the intermediate shaft for the M/96 engines (which has ZERO in common with the air cooled or late 993 engine based water cooled engines)

The TT/GT3 shaft VERY VERY rarely fails. It is not in a sealed roller bearing like the M/96 based engines. It literally sits in what amounts to 4 bearing clam shells. What you do not see in this pic is the shaft running the oil pump.

B

post-2685-1235374680_thumb.jpg

post-2685-1235374685.jpg

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What I understood from a Porsche technician is that the problem seems to be loosening of the bolts that secure the gear on the shaft. Whether this was from improper factory torque settings during assembly, inappropriate strength bolts, or a design flaw of some sort is unclear. The failures are relatively rare but disasterous for the few that have it.

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Thanks RoadsterDoc :)

I *thought* ALL the aluminum gears were riveted on ??? Maybe that was only in the race engines? Now I need to dig out some parts!!

B

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