What are the tell-tale signs of a worn timing belt?

 

If its got lots of cracks in it, and edges of the teeth look rounded and its got more slack than its sopposed to have, or over 100,000 miles.

 

They are cheap. Best to just replace it, the rad hoses and serp. belt. You can buy just the belt or a kit that comes with new tensioner. If waterpump is origanal you may want to change that too while it is apart.

 

The symptoms of a worn timing belt are that the engine doesn't run any more. In most failures that I've seen, the belt ends up loosing a few teeth, and the valve and sometimes the ignition timing get too far off to run. The tensioner will keep the crank, distributor if equipped, and cam in good time as it will take up any slack on the 'undriven' or unloaded travel of the belt. One portion is in tension pulling dist & cam, the other side is along for the ride. Most times the crankshaft will eat a few teeth, and that's that. It won't hurt the valves, and generally happens when one goes to restart, and it just won't.
Some belts had rounded teeth from the factory and some had square cornered teeth. Vintage dependent and I have no clue why.
tom

 

So no real performance difference until it breaks?

 

no. unless it has skipped time. then it will run if at all.