Edgy01

This afternoon while troubleshooting an odd tinny noise from the rear of the car (seemingly only when in SPORT mode) I experienced a serpentine belt failure. The 06 S has a bit over 34,000 miles on it and first displayed a "Warning Battery Generator" display (central) at the same time the steering got very heavy. We (I had another Rennlister with me!) then began to think through the symptoms as we were inward bound to the house fortunately at this time. The first thought was BELT! Within perhaps 60-120 seconds the warning "High Engine Coolant Temp" alert displayed in the center. I watched the coolant (EGW) go up, and the oil temp climbed. I literally rolled it into my garage and shut it down. It began to steam like a locomotive! Popped the hood and looked around. No serpentine belt. There was a small piece of it left under the engine deck. We later drove back up my street and looked for the rest of the belt but never found it.

Several weeks ago I had been mentioning to my service representative about the smell of burning rubber under the deck. They never checked it out. I'm guessing that it began to go south back then, finally letting loose today, fortunately, VERY close to the house. I'm glad I wasn't out on Route 1 or something at Big Sur, out of mobile phone range. I've been doing the usual visual belt inspection at service intervals, seeing no indication of deterioration.

1 800 Porsche, and they will be picking it up Monday morning. Stand by this channel for more as it is learned.

ADias

That was unfortunate and unusual. A belt failure at 34k miles and less than 3 years !?! That is unacceptable.

Was your belt ever touched and perhaps tensioned wrong?

Edgy01

I've never adjusted the tension on the belt but it felt spot on every time I have done a cursory inspection. The tension felt the same as every other serpentine belt I have tested on other cars, including other 997s.

gota911

34,000 miles for a belt is unusual. It could be that one of the pulleys has started to bind, putting additional strain on the belt. The worn out belt could be the symptom and a bad pulley the cause. Make sure they check all of the pulleys before they put a new belt on the car.

uzj100

Hmmm, good tip, Tim. Dan, I'm going to try to make it in to the dealer on Monday to go over it with you. VERY glad we were close to your house and NOT on our Rte 1 trip!

ADias

It's either that or a bad belt. It's unfortunate that Dan only has a little remnant.
In any case, this is a fluke.

Edgy01

Thanks for the tip about a poss. bad pulley. I'm going to retrace my route on my bike tomorrow to look for more debris!

ADias

Thinking about it... does a bad pulley make sense? Unless it was a deflection pulley or the AC pulley (and you were not using the AC to not notice its low output), which might not be noticed, any other pulley would have a symptom, like higher temp (water pump) or lower voltage (alternator) or heavier steering (power steering). What do you think?

Looking at the serpentine belt diagrams on the M97 and the new 9A1 engines, the M97 has a fairly convoluted path through 8 pulleys. The 9A1 is far simpler (less tight) w/ only 6 pulleys...

dD/dt

Something like a bad alternator bearing would cause an increase in friction/wear and eventually failure without necessarily affecting the alternator. Could be an idler pulley, or any of the other accessories. Also, if anything has become misaligned, that would create a problem. I went through this when I got a new alternator on a 95 Maxima - the new one didn't get shimmed, or the shaft was a bit shorter, or something (long time ago) - anyway, misaligned pulley and the car chewed up 3 serpentine belts in a week.

Any possibility of little rodents taking bites and creating stress risers?

GSIRM3

Several months ago, I noticed a strong smell of rubber burning coming from my engine compartment on my 07 S. At the time, I thought it was the clutch that I was smelling, but I had not been driving the car hard, and in fact never abuse the clutch. My belt has not failed and I just went out to the garage to check it and it looks OK, but I wonder now if I have a problem.

Fishdoc

Thanks Edgy for heads up.
Hope problem is worked out without a snag

Macster

can cause pulley to be slightly misaligned. Belt thus runs out of position as it encounters this pulley and one edge will rub against side of pulley. This can wear out belt enough to cause it to fail if wear reduces belt's width sufficiently. The belt is under extra strain too from its ribs mistracking the grooves of the pulley.

Or this failure mode can wear side of pulley to the point the side of the pulley simply falls away and allows the belt to severely mistrack. In this case the belt can then shredded and break or just jump off.

(And not finding belt is not uncommon. Lost motorcycle chain once and looked all over where it came off -- just a block from house -- for it and never found it.)

The belt may be a single point failure or it may arise from some other failure with the belt failing being the most obvious sign.

Whenever a belt fails a thorough inspection of all the accessory drive pulleys and belt idler and tensioner rollers is called for to ensure their is no underlying cause of the belt's failure.

Sincerely,

Macster.

kdurg

Interesting thread. Dan, glad you made it home ok and didn't get stranded.

Question for those that smell the burning rubber: Do you notice this smell after really getting on the car and hammering it ? Or, is it during normal driving ?

gota911

I am guessing that what you are experiencing is the cosmoline heating up after the car has fully heated up. It smells a little like rubber burning. Porsche puts the cosmoline on the bottom of the engine to protect it.

springgeyser

I keep a a spare belt in my car. It's cheap $34 insurance.