Amroth

So I was driving down the highway when I heard a loud noise in the engine bay. The battery warning came on so I knew one or more of the belts have come off. I stopped my car after 30 seconds on the side and opened the engine lid.

The pulley assembly for the alternator had come off and the parts were sitting on the engine tray. Unfortunately they caused some minor damage when they flew off, especially making a small chip on my cooling fan (hopefully not bad enough to need a replacement)

I picked some out except for one of the large pulley halves and it was so hot that I burned my finger. It seemed jammed anyway so I decided to pick it out when I got home. the alt belt was loose and didnt seem to be rubbing badly on anything, so I decided to limp home since the battery should last enough for another ew minutes (the cooling fan and compressor belts/ pulleys were fine.

That was a big mistake, that pulley piece came loose while driving and jammed against the crankshaft pulley towards the end of the drive home, effectively grinding the edge away to a degree and rendering the part unusable. This was a hard lesson to never EVER leave any loose parts when driving (duh, what was I thinking!)

Here are some pics until I make better ones. Apologise for the quality. My questions are:

1- My garage painted the fan and put it back in late 2014. So thats way too much time to tell them "You guys didn't torque the pulley nut properly" I'm guessing?

2- I will inspect the nut again to make sure the threads are ok. If they are, all I need is a new pulley half and I can do this at home with my torque wrench, right?

P.S. Is it normal that the bolts on the cooling fan pulley are not the same?

Rocket Rob

The pulley bolts/nuts should be the same but there is no harm if they are not. They should be M6 studs with nuts but I have replaced one of mine with a bolt when the stud broke. I will replace it eventually with the correct part.

I would inspect your fan carefully to make sure that its ok. The picture makes the chip look significant. You don't want the blade breaking and flying off damaging your engine cover or anything else.

Is there a torque for the alternator nut? Not that I've seen. I've always done it as wrench tight.

Amroth

Hey Rob

I will take a proper photo so you can see it the chip properly. Thanks for the info about just needing it to be wrench tight. I suppose its something I should check every couple of months

Do you think I'll have enough battery power for a 20min drive to the workshop? I need to ask the OPC for a steering rack recall and gearbox fluid top-up anyway...

I guess if that pulley half didn't get grinded I could have fixed it on the spot eh :/

Vandit

In addition to the parts you recovered, there are 6 thin shims that go either between the pulley halves or on the nut side of the halves. These are used to adjust belt tension. On a new belt, typically all 6 go between the pulley halves.

There is a torque spec on the nut but I forget, and actually applying it would require some type of crow foot torque wrench arrangement.

I usually aim for good and tight with a bit of blue Loctite.

Rocket Rob

Found the torque spec. Its 37 ft-lbs.

https://rennlist.com/forums/964-foru...correctly.html

911Jetta

Not the best picture, but it shows the shim/pulley arrangement.
I hope the fan is still OK?

-nick

Bad luck. If the fan is just chipped paint, then make sure to touch it up soon with some good enamel. Bare magnesium deteriotes quickly.

Odd that you lost the thin tension adjusting shims, or they were left out. Might as well check to make sure the hub bearing spins smoothly and the alternator shaft spins smoothly too.

AVI_8

Hi, from the pic of the fan you posted it looks not too badly damaged, you should file it gently and dress it out with a round file until the damaged area is blended, that should prevent any stress cracks from forming.
That's what aircraft engineers do to jet engines when they've ingested a stone or bird, you'd be amazed at the level of damage which is still within tolerance after such damage.

cscrogham

Don't drive the car that far with no cooling fan.

JohnK964

Inside belt is still on fan should turn as usual

cscrogham

Copy that