I found the source of the noise from my engine. It seems the belt tensioner is bouncing around while the engine is running. I suspect at 125K, it is due for a replacement.

While watching the belt itself, I notices the alternator pulley move in and out slightly while the engine is running. I wonder if the that is normal or is it due for replacement as well?

If I'm going to have the belt tensioner replaced and possibly the alternator, is there anything else that is wise to do at this time? I did have the belt itself replaced 10K miles ago so it is still in good shape.

Thanks,

Most unusual for the tensioner or the alternator pulley go bad. I wonder what kind of belt you got when you had it replaced.

Klaus
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Did you do your Random Act of Kindness today?

The replacement belt was installed at a dealer so I assume it is OEM.

Funny thing is the service tech agreed that the tensioner was the problem and source of the noise. Now that he replaced it, I still get the noise and still see the new tensioner bouncing around while all the other pulleys seem to be spinning smooth and true.

I can't imagine what would cause this condition. Could the belt be somehow faulty in that it is stretched at one spot?

Just wondering if anyone has had this problem on the boucing tensioner and 1 Hz sound that comes from the belt as a result.

I have the same problem on my 2000XC.
I did replace the pulley and the noise is still there.
However mine only makes the noise when cold and pretty well go away when warmed up.
I tried spraying on a belt dressing and that did not change a thing.
I used the hose trick, hose on the pully and the other end to my ear and the noise appears to be from the pulley.(go figure)

I'll wait and see what happens.

You need to take a close look at your new belt. Specifically at the weld/join on the belt. Make sure it is seamless and flat. Any imperfection will cause the tensioner to bounce over the mark.

Klaus
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Did you do your Random Act of Kindness today?

I seems to me the problem is coming from the alternator and I've decide to replace it. I know how to get the belt off but I'm wondering if I can remove the alternator from the top or is it one of those operations that require the bottom valence panel to come off or the right wheel etc.

Is there a good reference on the web for alternator replacement steps for the 00' V70?

This is all I could find for a 2000. 1999 and prior are different and harder.

http://www.justanswer.com/volvo/1e9no-trying-remove-alternator-2000-volvo-v70.html

I am still surprised that you haven't replaced the serp belt. From your initial write up, you didn't have this problem with the old belt???

Klaus
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My advice is free, so you got what you paid for...

I forgot to mention that I had a little cooling system work done on the car while we were on holiday. The shop noticed the problem with the belt and tried a different belt as a test, but they found the problem persisted. They suggested replacing the alternator as they've seen this problem before. That's why I decided to give it a try.

btw -- I'm also going to replace the belt with a new one anyway while I have everything apart.

Update: got everything apart tonight. The trick to getting the old alternator out was to orient it with the backside facing up and then rotate the alternator so the bolt flanges were in a plane parallel to the timing belt.

One question: Does anybody know the torques for the A/C compressor and alternator bolts?

A/C mount bolts are 29 lbs, probably the same for the alternator. If guessing, 25lbs would be safe.

Klaus
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My advice is free, so you got what you paid for...

I found the alternator a little tricky to remove/install so I snapped this pic of how I got it in/out of the engine bay. The way it worked for me was to orient the alternator with the backside facing upwards and then rotate it so the alternator mounting flange plane was parallel to the plane of the timing belt. It was still a squeeze but it worked.

Also use a t-60 torx bit to rotate the serpentine tensioner to get the belt on and off.

btw -- engine now runs as smooth as new with the new alternator.

Thanks for the help Klaus