Hey everyone,

Long time thread stalker, but first time new thread. I went through 20 pages of searching to no avail (which, btw I can’t get over how many other sub-forums have issues with belts; keywords “bad pulley”), so here’s the dilemma:

Well, first a little history;
Bought the car in Sept 14. Wasn’t looking for a new car, but happened across it. 51k miles on it, black with grey/black interior, panoramic moon roof, heated seats, etc. Didn’t know it was a titanium or what that meant, but the mileage was low and the price was right. Went home and started reading up on it. The car build was from 10/06 so I thought maybe I got lucky and it had the revised coolant pipes. I was incorrect. May 2018, at 135k, the pipes went out. Towed it to the dealership because... why not. They told me it would be $1200 in parts and $1300 labor. I told them, “No, it’s going to be $75.00 to tow it home.” Towed it home and started tearing it down. Did the pipes, replaced plastic hoses, spark plugs, etc. Took my time and tore it down the first weekend, rented a car, waited for the parts and put it back together the third weekend. As I was putting it back together, I noticed the perpendicular cracks on the serpentine belt. I’m no mechanic, but I knew it needed to be replaced. Six or eight months ago the drive shaft went out. Not a big deal, I knew it was going to happen. The local indy quoted $50.00 to change it out (I got the one from amazon for $200). So, yeah, he changed it. I picked it up the next day and he mentioned I should change out the belt. Oh yeah, I had forgotten about that. He quoted $150 to change it including the $100 for the OEM Continental belt. He needed a week to order it and I would drop it off the following weekend. Well, for whatever reason, something came up or something, I forgot about it...

This past Friday evening I started up the car to drive home from work and I heard a squealing with a tap coming from the driver front tire. It must be the belt because we’re experiencing a lot of humidity up here lately. Drove the 25 miles home and didn’t think anything of it. Went out to run errands late Saturday morning with no squealing or tapping or anything. Well, the belt reminded me... at a stoplight... of a four lane city road... at 1:00pm... on a Saturday afternoon... that it needed to be replaced. A subtle, whispery pop and the car stalled. Tried to turn it over and nothing. Hazards on and pop the hood and I could see the remnants of a battered and bruised and, frankly unhappy, serpentine belt spewed across the engine bay. Luckily a police officer was driving by and blocked traffic while I pushed the car off the main road and waited for the tow truck. The tow truck put it up on the flatbed and I can see strewn rubber dangling out of the plastic undercoat like the dragon from Thor Ragnorok with its tongue hanging down. This little piggy was not going all the way home today.

So I had it towed to the indy because he had already quoted me and I figured it would be $75 or so to tow and now was probably a good time to replace the belt.

Then he called me this afternoon to stop by and see what he was seeing. Well, if I have to leave work early to make sure the car’s ok, then so be it. I stopped by and he said that when he put the belt on and turned it over this morning he heard some squealing and saw some smoke. By the time he went over to the engine bay, the smoke was gone, so he couldn’t identify which pulley was seizing. He checked every pulley by hand before putting the belt on and felt no play. He started it up with me there and there was no squealing or smoke. We let it run for about 15 minutes, turning on econ and turning it off, rotating the steering wheel, giving it gas, etc. No smoke, no squealing. So far as either of us could tell, nothing is seizing. Battery is fine as well. Have not seen a dip in voltage in almost five years (other than the android radio install with its WiFi always on debacle, but that’s another story). So the question is:

When does a pulley intermittently seize?

We did look at the shredded belt afterwards and noticed there seemed to be some melting on the middle channels. The belt shredded along the channels (not in the direction of the cracks, which, btw were definitely worse).

He requested to keep he car overnight and will turn it over cold start tomorrow morning to see if he can identify which pulley (ie maybe it’ll smoke again?). But, he seems as baffled as I am. Thoughts? Suggestions?

 

Oh, forgot to mention, 154k on the odometer now... so far as I know, other than the above listed, everything is original.

 

154k on the belt as far as you know? I would assume when it broke, some bits got caught around one of the pulleys and that was what the smoke was from after the startup since you said it was shredded. Just a guess.

 

Fair guess. Thank you.

 

The A/C Compressor pulley spins all the time but only has load on it when the A/C clutch engages. Maybe it's intermittently locking up when it tries to engage.

 

At 154k - the Cayenne is way overdue, for Serpentine belt replacement. OEM belt only good for 90-110k. Might as well do the water pump too.

Start collecting metric tools like, right NOW...

 

Having done something similar on a prior vehicle, a piece of gravel had gotten caught into the belts and rather than being ground to dust, flayed the belt right down the middle and left only a scratch on the metal pulley.

 

Thanks for the feedback, guys. Still waiting to hear back from the indy. I can’t remember the last time I had the A/C on... maybe last year? It was definitely off when the belt went. If it’s not under load, I wonder if it could intermittently seize.

 

So he ran it a few times for hours today with no squealing or smoke... so perhaps just a piece of the old belt like previously suggested. Only way to find out for sure is to drive it the fifty miles to work and back tomorrow. Thanks for the help and time, everyone! If it pops again, I’ll be back.

 

I can’t remember the last time I had the A/C on... maybe last year?
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You should always run the AC even when just using heat/defroster. It not only keeps moisture out of the interior air, but it exercises the compressor. At least run it, on purpose, 10 minutes a month at a minimum.