when should timing belt be replaced...?

On a 2001 Toyota Corolla, when should timing belt be replaced?--owner's manual is not clear. I currently have 100K miles on it. Will changing timing belt improve performance any?--I noticed it has slowly become a bit sluggish over the past year or so altho it runs fine otherwise with zero mechanical problems.

When timing belt is replaced, is it advisable, as a mechanic suggested, to have water pump, tensioners and other assorted stuff done at the same time? He quoted me about $250 for timing belt alone but double that if everything else he recopmmended was done too.

Thanks.

It should be done about every 100,000. No performance gain, but if it breaks, you're up for nightmarish repair bills. :cheers:

I've just been told elsewhere that my Corolla actually has a timing chain--not a belt. Someone told me the reason the manual is vague about Corollas is because the chain is expected to last more or less the life of the car and need not be replaced under most circumstances. True?

timing chains last longer than belt but over time, it gets loose and noisy. while replacing the timing belt, you have best access to change water pump, pulley etc.