nickbw898 wrote: ↑05 Jan 2018, 03:17 That's all true but there is another component on the shedual for change at the same time/miles interval and I have found many don't know about it. It's the alternator pully (AOC) which has a ratchet like mechanisum for preventing over-run. This is somewhat difficult to replace in situe (but doable with the right size tools and smallish hands) it also adds another £50 to the parts list. If the bearing etc goes out it will take ot the cam belt in all likelyhood.
It is indeed wise to inspect all running pulleys on the serpentine belt, when replacing the first timing belt.
My experience on a 2003 S60 at 100K miles is different: the A/C pulley was noisy (like a friction noise from the dry bearing) so I went replacing the bearing. The old bearing was indeed dry it may have lasted another 10K before seizing. We don't have the diesel engine here (the infamous and excellent D5) but the guys in Europe have plenty of them. Plenty of owners had their D5 engine destroyed when the A/C pulley seized not far from the 120K miles mark, the serpentine belt wrapped around the crank pulley, and the timing belt was forced to slip on the cams. However, this rarely happens on the gasoline engines when the A/C pulley throws the serpentine belt.
I've also removed and inspected my alternator at 100K miles. The clutch pulley was working fine, with no play. I don't think it will last another 100K miles, but no doubt is good for some 50K miles or so. What is interesting is that upon removing the regulator, the brushes inside were worn at about 2/3. So just by the brushes the alternator had only about 1/3 of its life remaining.
Finally, the bearing on the tensioner on the serpentine belt had a bit of play and was slightly dry: it may have lasted just another 20K miles so I went replacing it.
So basically indeed at the 100K mark both belts and all pulleys need inspected as there are a few that need attention. The only one I believe it's solid and will last until the second belt, it's the water pump. I have one day searched about 6 or 7 water pump failures on S60's reported on several forums: all without a single exception were aftermarket units that some mechanics put in place of the original unit. Some of these happened to unfortunate owners who bought the car with the timing belt already replaced, not aware they were already running on a cheap aftermarket water pump. As a general rule of thumb, if a seller says the water pump was also replaced, chances are the job was done by a cheap garage who doesn't know Volvo and who used cheap parts.