Pontiac Repair: timing chain, cam gears, high mileage

Question
99 grand am 2.4.  car wouldn't start, to it the a shop they said it was the timing.  they replaced the time chain, value are good, ran good for about 70 miles, then it wouldn't start again, just turns over.  back to same shop, they said time was missed up again, what could be causing this, thanks.

Answer
Hi Terry:

Well with out seining it I can't say for sure but My guess is either the tensioner for timing chain is bad or one of the shoes/guides for the chain broke. There are 3 guides along with the one on the tensioner one of those may have broken. Usually the one on the top between the 2 cam gears is the one that breaks and then the chain Will jump. usually it jumps when your trying to start the car they don't usually break when you are driving down the road which is a good thing because then they bend valves in the head which gets ugly. when they jump time when your starting the car it usually doesn't bend any valves. On Any of these engines that are high mileage I ALWAYS quite the chain/guides and tensioner with the job. It's a case of pay me now or pay me later because stuff like this happens when you piece it back together. to do it all at one time doesn't require any extra labor because it's all apart anyways to do the job twice because you didn't replace all the parts with new ones gets costly and is counter productive. good luck :-}