Hello

What is the service (ie change) interval for the thermostat?
I'm coming up on 5 yrs at 68,000 kms. and want to know if I should change it as part of routine maintenance.

Thanks
Walt

change it when you do your coolant flush and might as well do the housing and gasket as well, thats ho wi did it at 48,000 when i did my coolant.

There isn't actually a change interval for the thermostat specified. That's not to say they CAN'T fail, but I haven't experienced this as being a common problem on most cars these days. My 2002 currently has 234,000km on it, with the original thermostat. It always runs at a consistent temperature, and has never given me a reason to question it. To my knowledge, my 1965 even has its original thermostat in it, and it too works just fine.

I've had to change a couple of them over the years due to them sticking open and running too cold - but I have yet to have one stick closed causing an overheat condition.
I would think that GM wouldn't have buried the Eco's thermostat in such an awkward place (requiring removal of the exhaust manifold on automatic cars) if it was expected to be a maintenance item. I suspect that they expect it to last the lifetime of the car without service.

If for some reason the car was overheated (hose, rad failure, etc.), then I would replace the thermostat at that time - but otherwise I wouldn't go through the bother. My brother traded in his 2002 GT with the Ecotec earlier this year at 176,000km, and it too never had an issue with temperature - we just changed out the coolant at the 5 year mark.

Changing it at this point wouldn't cause a problem, but most likely isn't necessary. Draining the cooling system on these cars is easy anyway, so unless the temperature becomes erratic, I wouldn't worry about it.
John

Hey John

Thanks for the post. I've had them stick closed on me in the past with other makes of cars. One time, the engine light came and soon after the head gakset went on it. Anti freeze started leaking into the engine.
Since the ecotech is an all aluminum engine, I don't want any overheating. Since rading your post, I'll leave the thermostat allone when I change the coolant next summer.

Walt

ps If the thermostat in the ecotech does fail, does it fail open or closed?

I don't think there's ever a way to predict "how" something may eventually fail, but there seem to be more diagnostics included in GM's manual determining that it's sticking open, rather than closed. The "sticking closed" scenario seems to fall into the "unlikely last resort" category in their scheme of diagnostic troubleshooting - if that offers any peace of mind.
In the manual, replacement doesn't actually APPEAR to be terribly difficult if you have a manual transmission - but most of their diagrams seem to conveniently have a lot of stuff already removed for illustrative purposes. Since they only show such a small specific area in their diagram, it's very difficult to picture overall - especially since I own a 2200 myself. I remember looking briefly at my brother's Ecotec when he had it, and it didn't look like a lot of fun. A shop had told him that his water pump was leaking when he had it in for an oil change. I looked myself and couldn't see any sign of leakage - maybe a slight bit of weepage indicated, but no wet leaks. He had the car for over 1.5 years after that, and it never appeared any different, or required any coolant to be added. I guess they missed out on their unnecessary $600 estimated job... and some people wonder why I still like doing my own oil changes.
John