Serpentine belt came off pulleys. Problem itself.. or a symptom of something worse?

[crew]

Hey guys,

Was driving home this past Thursday, had the AC going and went to step on it to get a guy off my back, and the car went into limp mode. Got her over to the side of the road, and couldn't get her to start and idle. Checked the CEL, and got coolant temp. sensor (p2181) and cyl. 2 misfire. Pulled the plugs, they looked alright, and the temp. sensor has been on for a while - assuming thermostat stuck open, haven't gotten to replace it.

Long story short, got AAA to drag me home (it was less than half a mile to my house, ironically). My dad comes over and we take a look, and he's getting the same thing I was.

Car will turn over, and reach maximum of 2k RPM, but will not idle or move forward. We pop the hood, and find that the serpentine belt (intact), is off track. I really don't have any more information than that, but I am curious if there is potential for this to have been something popping the belt off track, or if it's a symptom of something more serious. I want to have some idea before I call my shop to have her towed over.

Car has 140k currently - had my timing belt replaced approx. 25k ago, and my serpentine belt was said to be in good condition, so it was left in. It still seems to be intact, but will be replaced anyway.

Any ideas? Pic for clicks:

[mec]

First thing you should do is reconnect the serpentine belt. Get a 17mm box wrench and Stick it over the tensioner and pull back, then reinstall the serpentine belt. Go on a drive, clear codes and let us know what happens

[aluthman]

If there is no resistance on the tensioner, you'll know why the belt came off.

[crew]

Will I be able to access the tensioner without removing anything?

Also, if someone has Bentley and can post an image of the proper path - I searched online (quickly, on my phone, at the time) and couldn't find it.

I will give it a shot tonight if I can manage!

[Charles.waite]

Will I be able to access the tensioner without removing anything?

Also, if someone has Bentley and can post an image of the proper path - I searched online (quickly, on my phone, at the time) and couldn't find it.

I will give it a shot tonight if I can manage!

The tensioner release arm is right next to the top pulley of the serp belt.

[yeoj112689]

I would think the tensioner would be the main place to look. If it was any other pulley I would think you would hear it and know well before it broke.

Other options would be:
Wrong belt
placed on wrong
not placed fully on track to start

[crew]

The tensioner release arm is right next to the top pulley of the serp belt.

Got it. So it'll just be a matter of releasing it, if it's still in tension?

I would think the tensioner would be the main place to look. If it was any other pulley I would think you would hear it and know well before it broke.

Other options would be:
Wrong belt
placed on wrong
not placed fully on track to start

I'm assuming that the belt was correct (was never replaced), and if it was off track for 25k miles, I'd be impressed.

Provided the tensioner is the failure point, what will it look like / how will I know ? I have seen other threads with failure in so much as the entire thing coming apart, and I do not believe that is the case here.

Provided the tensioner is still in working order - any ideas as to why the belt may have jumped in the first place ? Overload with AC blasting and sudden acceleration?

Thanks for all the help so far, guys. Much appreciated. Just want my baby back on the road asafp.

[Charles.waite]

Honestly, aside from a broken pulley, the only reason the belt would come off is a broken tensioner.

[crew]

Honestly, aside from a broken pulley, the only reason the belt would come off is a broken tensioner.

I have to agree with you, since the pulleys all seem to be functional.. I was just holding out hope that it might be a fluke. We'll see tonight.

[fly300kts]

A seized component might trigger that as well: steering pump, A/C clutch, idler, tensioner

Phil

[yeoj112689]

I would replace the tensioner and go on with your business as long as nothing else looks off. You do not want to get stranded somewhere, end up paying more to get it home than the tensioner would of in the first place.

If it was another failed component I would think it would break the belt not throw it off.

[crew]

A seized component might trigger that as well: steering pump, A/C clutch, idler, tensioner

Phil

Phil - should all components rotate freely when the motor is not running?

I wish I was next to the car right now, I won't be able to check all this until late tonight, but I can't remember from Thursday night (was away all weekend).

[Charles.waite]

Phil - should all components rotate freely when the motor is not running?

I wish I was next to the car right now, I won't be able to check all this until late tonight, but I can't remember from Thursday night (was away all weekend).

Yes they should.

[crew]

Does this look to be the correct path / components ? Or at least close ?



Sent from my HTC One X using Tapatalk 4

[yeoj112689]

The components should all be free moving with the belt off (outside of the crank)

[Charles.waite]

Does this look to be the correct path / components ? Or at least close ?



Sent from my HTC One X using Tapatalk 4

Yea that's it. Sorry I snapped a pic of the Bentley diagram earlier but I forgot to post it.

[crew]

So, sorry for this terrible (portrait) video, but it doesn't look good for the crank pulley. Attention to the rotation axis and the sudden stoppage when rotated, I couldn't get a great grip on it or reach it by hand.

Thoughts?

[schowe]

From the looks of that video, looks as though maybe your crank pulley seized up. I'm not completely sure of the design of these ones, but on my Nissan, it was as simple as removing the crank bolt (a large impact wrench was used) and swapping out the pulley. On my old car, it was the rubber harmonic balancer that would dry-rot and crack/fall apart over time. You might want to pull the bumper off and take a better look at it.

[crew]

From the looks of that video, looks as though maybe your crank pulley seized up. I'm not completely sure of the design of these ones, but on my Nissan, it was as simple as removing the crank bolt (a large impact wrench was used) and swapping out the pulley. On my old car, it was the rubber harmonic balancer that would dry-rot and crack/fall apart over time. You might want to pull the bumper off and take a better look at it.

I will hopefully have some sunlight left tonight when I get back.. this would be my first time pulling bumper - is it the retaining clips on the skid plate and then 11 (?) screws on top? I peeked the DIY but didn't give it a once-over. Looks like a T25 and T30 will be needed. I think at the least I'll hold my camera down close enough to get an idea of what the front looks like.

Will a crank pulley failure have any impact on timing ? I'd love to keep her out of the shop, if it's simple enough that I can do it myself. I imagine replacing the pulley would entail the bolt too, and may as well replace the belt while it's off.

[Charles.waite]

I will hopefully have some sunlight left tonight when I get back.. this would be my first time pulling bumper - is it the retaining clips on the skid plate and then 11 (?) screws on top? I peeked the DIY but didn't give it a once-over. Looks like a T25 and T30 will be needed. I think at the least I'll hold my camera down close enough to get an idea of what the front looks like.

Will a crank pulley failure have any impact on timing ? I'd love to keep her out of the shop, if it's simple enough that I can do it myself. I imagine replacing the pulley would entail the bolt too, and may as well replace the belt while it's off.

Looks like the crank pulley lost a few bolts. I would NOT drive the car at all. If the pulley gets jammed it could affect the timing belt and potentially cause it to snap, more or less destroying your engine.

You've got the take the front end off and put it into service position and replace those bolts. You might have to replace the pulley too if its bent. I wouldn't mess around with the pulley to be honest.

[crew]

Looks like the crank pulley lost a few bolts. I would NOT drive the car at all. If the pulley gets jammed it could affect the timing belt and potentially cause it to snap, more or less destroying your engine.

You've got the take the front end off and put it into service position and replace those bolts. You might have to replace the pulley too if its bent. I wouldn't mess around with the pulley to be honest.

Poor thing has been sitting at my curb ever since, no need to worry about driving it.

Stranger things have happened, I'm sure.. but any chance that the pulley itself sheared along the bolt path? It almost seems like that is the case, rather than just having lost bolts and hanging. I will hopefully be able to take a look at it better tonight, but no promises.

I think regardless, I'll have to bring it to my shop and have them diagnose it, to make sure no more additional damage has been done. If the pulley needs replacing, should I go ahead and go lightweight, or is it moot? I've heard minimal vibration as a result, but I am just feeling it out.

[fly300kts]

Light weight pulleys are not recommended because you lose the damping function

Phil

[Charles.waite]

Poor thing has been sitting at my curb ever since, no need to worry about driving it.

Stranger things have happened, I'm sure.. but any chance that the pulley itself sheared along the bolt path? It almost seems like that is the case, rather than just having lost bolts and hanging. I will hopefully be able to take a look at it better tonight, but no promises.

I think regardless, I'll have to bring it to my shop and have them diagnose it, to make sure no more additional damage has been done. If the pulley needs replacing, should I go ahead and go lightweight, or is it moot? I've heard minimal vibration as a result, but I am just feeling it out.

DO NOT go lightweight. The vibration from those is absolutely terrible. Go either OEM or fluidampr those are the only two options I would consider.

It's possible the pulley has some rounded out bolt holes, but I doubt they're sheared, there really isn't that much stress on the pulley. My guess is they weren't properly torqued when they were replaced by the stealership. Its dead simple to replace them, it's just getting the front end off that takes a bit of time. You don't need to touch the crank bolt either, the pulley fits over the crank bolt so you just undo the 6 (or 8, I can't remember) pulley bolts, replace said bolts, and button the front end back up. The crank bolt is torqued to 50ft lbs + 180* or something absolutely insane so you need a specialized massively long (like 5-6feet long) breaker bar to torque it properly. So as a rule you don't touch that unless you absolutely have to.

[crew]

Light weight pulleys are not recommended because you lose the damping function

Phil

That's one thing I remember reading - thanks Phil!

DO NOT go lightweight. The vibration from those is absolutely terrible. Go either OEM or fluidampr those are the only two options I would consider.

It's possible the pulley has some rounded out bolt holes, but I doubt they're sheared, there really isn't that much stress on the pulley. My guess is they weren't properly torqued when they were replaced by the stealership. Its dead simple to replace them, it's just getting the front end off that takes a bit of time. You don't need to touch the crank bolt either, the pulley fits over the crank bolt so you just undo the 6 (or 8, I can't remember) pulley bolts, replace said bolts, and button the front end back up. The crank bolt is torqued to 50ft lbs + 180* or something absolutely insane so you need a specialized massively long (like 5-6feet long) breaker bar to torque it properly. So as a rule you don't touch that unless you absolutely have to.

So, is 25k miles a reasonable estimate for improperly torqued bolts to wiggle themselves out and cause the belt jump? I drive practically all highway, 150 miles per day, and not unspirited.

This is frustrating, because if the cause is indeed bolts being improperly torqued - assumedly after my timing belt job, then I don't want to take it back to the same shop (wasn't the stealership).

Any recommendations for a shop around north Delaware ? I had taken it to The Audi Shop in Wilmington.

[crew]

Also, if I manage to get to the pulley - what torque would I be looking at for those 6 bolts ?

Tonight will probably just entail getting the bumper off and getting a closer look.

[Charles.waite]

Also, if I manage to get to the pulley - what torque would I be looking at for those 6 bolts ?

Tonight will probably just entail getting the bumper off and getting a closer look.

Edit. here are the torque values: 10Nm (7ft-lbs) plus 90deg (1/4 turn)

Theyre TTY (Torque to Yield) stretch bolts and should generally be replaced every time they're undone. I would do that, they're cheap. I'm sure a local dealer would have them in stock.

[fly300kts]

Also, if I manage to get to the pulley - what torque would I be looking at for those 6 bolts ?

Tonight will probably just entail getting the bumper off and getting a closer look.

Europaparts has the pulley (I replaced mine at 140K) and the replacement bolts

[crew]

Edit. here are the torque values: 10Nm plus 90deg (1/4 turn)

Theyre TTY (Torque to Yield) stretch bolts and should generally be replaced every time they're undone. I would do that, they're cheap. I'm sure a local dealer would have them in stock.

That's a very good point. It's worth the peace of mind.

Europaparts has the pulley (I replaced mine at 140K) and the replacement bolts

I could've sworn I only found the replacement bolts at Europa, but I will check again. They're very local, so I could hopefully get it quickly.

Thanks for the help guys! I will let you know what I find tonight.

[fly300kts]

Voila

http://www.europaparts.com/catalogse.../?q=06f105243j

http://www.europaparts.com/catalogse...t/?q=n10303607

Phil

[aluthman]

Im putting a Fluidampr on my car along with an IE crank pin kit. If you need any of the OEM parts I'm taking off, you can have them for the cost of shipping.

[crew]

Im putting a Fluidampr on my car along with an IE crank pin kit. If you need any of the OEM parts I'm taking off, you can have them for the cost of shipping.

That would be ideal!! How many miles on yours?

I would potentially only need the pulley itself, preferring to pick up new bolts, but I am hoping to get home in enough time to pull the bumper and have a closer look.

I will shoot you a PM tonight. Thanks!

[aluthman]

My car has around 106k on it. I'll have the parts back as soon as my engine returns from the machine shop if you want pictures or whatnot.

[crew]

Well, I didn't get to pull the bumper, but I found a telescoping mirror and did my best to record what I found.

The pulley face is totally sheared. It's hard to tell without pulling the bumper, but it looks like one of the bolts is missing.

Now what ? It seems like this would be a precursor to something more serious.

[aluthman]

As long as the timing belt gear didn't shear the keyway, I would think you would be fine internally. Hopefully the pulley was just installed improperly and that's what caused it to come apart. You need to get it apart to be sure. I pinned my crank and bought a Fluidampr in hopes of preventing this on my engine.

[crew]

As long as the timing belt gear didn't shear the keyway, I would think you would be fine internally. Hopefully the pulley was just installed improperly and that's what caused it to come apart. You need to get it apart to be sure. I pinned my crank and bought a Fluidampr in hopes of preventing this on my engine.

I'm hoping so. If one bolt is missing, that would lead me to assume that it worked its way out, and the others may have been loose enough to throw the axis off track and jump the belt. Maybe the irregular forces on the wobbling pulley caused the lock and shear ?

Another fat chance, but maybe I'll be home in enough time to try the bumper tonight. I got home late last night (like I said, I work 65 miles from home), and it was dark before I put all my stuff down and got back outside.

But yeah, definitely let me know when your stock parts come back, aluthman - I would love to entertain that idea as a replacement.

[crew]

Just got her back earlier this week, and she's running fine.

The crank pulley was sheared, and a small piece of metal ended up under the timing belt, shifting it about 3 teeth.

Could've been much worse - happy to have my baby back. Thanks for everyone's input/help!