I would do them by 120k or so, it may specify in the manual. GM ecotec engines having overextended chain tensioners is extremely common. Don't wait until it starts to rattle when cold or you start getting cam codes because you may already have damage by that point. This is not something to attempt to DIY unless you're very sure you know what you're doing.
I've done them myself on several of the 2.2 and 2.4L ecotecs and it takes a couple of hours and a few special tools, otherwise having a shop do it the estimates were $750-900 or so.
I've done them myself on several of the 2.2 and 2.4L ecotecs and it takes a couple of hours and a few special tools, otherwise having a shop do it the estimates were $750-900 or so.
