General: Odd noise, aux belt area

[Nick44]

As it happens, I have the alternator off my car in my hand right now!
(See my post Alternator Pulley)
The is no play at all in mine front-to-back (or in and out if you prefer)
The fact that you noise almost goes away when not under load could be related the the freewheel pulley I'm discussing, when the load in the aux belt is reversed slightly when freewheeling or engine braking.
Might be your clue to a fix.
The freewheel pulleys are known to go, thus my issue as well!

[zodski]

Nick44 - Looked at your post, and it does look as if this might be a possibility. Where did you order your freewheel pulley from? Thanks for the info.

[Nick44]

Well Zod,
As I havn't been able to fit it, it's available!

Part # is 30667878 £61.50 + Vat is what I paid at Volvo dealer.

[Nick44]

This is what it looks like, and the tool you need to fit it with.

[Nick44]

Just thought of a test for you Zod to avoid paying for a freewheel if you don't need one.
Take off the alternator and clamp it down to a bench or similar.
Put a Torx No 50 into the alternator shaft centre, and put the other end in an electric drill.
Spin up the alternator.
You are now driving the alternator on the output side of the freewheel.
If no noise, it's the freewheel, if still noisy it's the alternator.

[zodski]

Thanks for that idea, Nick. I'l do it tomorrow and see how thing go.

[grass hopper]

if the engine speed is steady and the noise is still there then it wont be the free wheel on the alternator.

listening to the clip at steady throttle the noise is still there.

[Georgeandkira]

Hello, A) Nick44: great posts on freewheel and tool. Thanks. B) zodski: If you can remove the alternator, just bring it to a rebuild shop near you. Either way (freewheel or alternator) they'd be able to fix it. Most all shops install rebuilds anyway. Kira

[zodski]

As Nick44 suggested, I have taken the alternator off and run it with a drill to see what happened. I didn't hear the noise from the video I made, so assume the bearings are okay. I did notice that there was a lot of black dust that fell out of the pulley when I took the end cap off. I also saw that the pulley moved a good 2-3mm up or down the shaft. In fact, at its lowest point on the shaft, it could actually rub against the alternator body (perhaps explaining the occasional, but rare, rubbing sound from the engine?).

Grass hopper, at higher revs (speeds), the noise does get quieter when the engine is allowed to come back to cruise revs. Its a lot louder during acceleration, and virtually quiet when the car is slowing down. Does this mean that the freewheel pulley could still be at fault?

As the alternator and air con. pump are the only two components on the aux. belt that have clutches, and I think I have eliminatd the air con. pump, it still seems to me that it is now most likely that the freewheel pulley is the problem (I would assume there to be only a change in frequency across various speeds if the source were the tensioner or PAS pump).

If this is the case, and I need the car yesterday and have advice not to use it until fixed, can anyone recommend alternator rebuild shops in the Sleaford/Grantham (Lincolnshire) area, or do you need a new home for the replacement kit that you have at the moment, Nick44?

[Nick44]

Sounds to me as if you have isolated to the freewheel pulley then Zod.
Loads cheaper than an alternator!
Yes, I was intending to return my unwanted pulley to the Dealer, so if you want it PM me your snail and I'll stick it in the post for what it cost me.
The special tool I borrowed from a friendly mechanic, but as your freewheel is that buggered I would be tempted to slice off the outer belt pulley with an angle grinder, grip the remains in a vice and just unscrew the shaft with a Torx 50.