my 03 sunfire timing chain tensioner just went out, car has around 110,000 miles
i got a timing chain kit and replaced the whole thing because i didnt know what part was broken but it looks like the upper chain tensioner that installs in the back of the engine was the cause it was stuck closed when i took it out providing no tension on the chain at all, i got lucky and got it replaced before my chain broke and engine went out of time.
just thought id give a warning to anyone with an ecotec that if their car is getting over 100,000 miles may want to consider get a timing chain kit installed before its too late, the kit comes with a revised timing chain oil nozzle which i guess provides more oil to the timing chain and a revised timing chain tensioner which is supposed to work better/ last longer, etc $150 well spent if you ask me