Owners of Ecotec 2.2 engines should heed the warning to have the timing chain, it's three plastic guides, as well as the balance shafts chain and it's three plastic guides replaced at or near 100,000 miles. I've never seen so much plastic for chains to rub against in any engine before this. Bolt breakage on the front timing chain guide is rampant. The upper one is not too bad to repair but as in this care, the lower one is horrible. I was unable to get the lower front guide bolt out and will have to find a mobile mechanic who is willing to come and try to get the broken lower bolt out. Had I designed this engine I would have tried to avoid the plastic guides by using small gears as idlers to make angled turns with the chain. I'm not going to come right out and call this a bad design, just not the best design possible. This otherwise good engine is marred by this not very durable chain guide design. I'm at about $750 in parts into this repair and now need a mobile mechanic to remove a broken bolt so I can continue repairing it. A machine shop replaced all 16 valves and their guides and I'm replacing the lifters. RE-assembly I can handle. This bolt issue is a complete bear.

I warn owners of the Ecotec to have their chains and guides replaced at 100,000 miles. It is a strange phenomenon for people with a "good running engine" to tend to leave it alone as if it will continue on forever. This is NOT the case with the Ecotec. In a constant war of friction between the chains and the plastic guides, something has to give and it is the plastic that loses the battle. If you own one, PLEASE take it in at your CONVENIENCE and have them changed rather than letting them break, leaving you on the side of the road to have it towed and far more expensively repaired at your EXTREME INCONVENIENCE.

Update from Jan 14, 2016: I removed the head and had a machine shop replace all 16 bent valves, guides, and valve stem seals. A metalwork shop repaired the lowermost timing chain guide broken bolt. This meant me pulling the block out and putting it back in. New head gasket and bolts. New Cloyes timing chain set and Balance chain set installed. Dropped and cleaned oil pan. Total cost of parts and outsourced services $1200. I did the work myself so there was no labor charge. Before the failure it wasn't using oil between changes. Afterward it uses a quart each week. Runs great but uses a lot of oil now.