Other then mileage is there a way to tell when it is time to change a timing belt? Does the belt show a particular wear pattern? Car in question is a 93 965 with 110k miles. Belt has 7K miles and there a very fine crack in the rubber on the inside of the belt next to one tooth. Crack goes across the whole belt width.

It is so easy to change the belt that it isn't worth the risk & worry to keep it on there. Make sure your car has had the damper added to the exhaust cam also to increase your interval to 30K, (I think.) This should have been done by Volvo at the first 20K service. You can see it as a black device behind the spokes in the cam pulley on the exhaust side. (It will be deferent looking than the intake side.)
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'96 965 at 89K. Had '85 745 Turbo Diesel for 200K.

If you have a crack across the whole width, change it. I first discovered Volvo's ridiculous timing belt life when my 20,000 mile belt snapped. As a first time Volvo owner I wasnt aware of the fact that the belt needs changing at every major service to be safe.

Graeme
1 Volvo(960)First and last. Once it's fixed, it's going.

If there's a crack across the whole belt on any tooth, it's time for a replacement.

Occasionally I've seen it where the belt is joined, that it will have a similar crack across the entire width (on the inside of the belt). You can sort of see the mark if you look at it carefully. But I'd be suspicious of the belt anyway with a crack in it. If it busts that tooth, it will break more also.

It might also pay to find out why the new belt has a crack like that. I put a brand new belt on a car with a different problem related to a tight top end. A hundred miles later, it had a similar crack in the belt, and it had jumped time.

It's unlikely that you have a similar problem, but out of the interest of potential expense vs. preventative expense, I'd get it replaced or replace it, whichever you usually do. Perhaps there's someone else who had a similar belt crack in the same manner.

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chris herbst, five volvos.