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I was thinkng about the Ecotech last night and I was wondering if it is a valve-interference engine. Also I wonder how bad the timing belt will be to replace.
 

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Not sure if it is valve interferance or not, but there is no timing belt. It's actually a chain... double roller, if I recall correctly.
 

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bob95065 said:
I was thinkng about the Ecotech last night and I was wondering if it is a valve-interference engine.
what is this? ive never even heard of it before

edit: actually used search and lo-and-behold there was the answer. :leaving:

ok, so that explaination was good, but im still a little lost. so the interference engine is a good thing or a bad thing? im confused.
 

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swatthefly said:
what is this? ive never even heard of it before

edit: actually used search and lo-and-behold there was the answer. :leaving:

ok, so that explaination was good, but im still a little lost. so the interference engine is a good thing or a bad thing? im confused.
It really isn't a bad thing, and not necessarily a good thing. All it is, is just that when the piston is at full TDC, and if the valve were to come down at the moment, it'd hit the piston. But then the cam and crank timing are such that they won't ever touch each other. Thats all it is, just clearance. I think just about any high compression engine runs an interference design because of how close the piston must come to compress.
 

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swatthefly said:
what is this? ive never even heard of it before

edit: actually used search and lo-and-behold there was the answer. :leaving:

ok, so that explaination was good, but im still a little lost. so the interference engine is a good thing or a bad thing? im confused.
I think it becomes "bad" only when the timing belt or chain snaps. If that were to happen in an interference engine, the pistons and valves would all smack together, bending all the valves. On a non-interference engine, if the timing belt/chain snapped, it wouldn't cause any major internal damage to the valves or pistons.

A lot of 4 cylinder engines used timing belts, which do not last nearly as long as chains, and are more susceptible to breaking. So regular maintenance of the belt is critical in an interference engine to prevent very costly damage. Since chains tend to be much more robust, having an interefence engine is not as big of a deal since the chains generally last the lifetime of the motor (although I have seen some engines that call for chain replacements too, but not all).
 

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A lot of GM's V8's (305 for sure and 350, I think) had timing chains but when put into passenger cars (vs trucks) had fiber reinforced plastic sprockets. This was done to get the engine a little quieter. I've spun the teeth of the sprockets at 120K miles in a 305. But because it was a "non-interference" engine, no real damage was done (other than having to hitchhike from nowhere with a wife and two toddlers). Had it replaced with the steel sprocket used in truck applications.

Anyone know what the timing chain sprockets are made of? Hoping they're steel and not aluminum or plastic.
 

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bob95065, do you own a Porsche 924S or 944? :D

Most 924S and 944 owners have a very good knowledge of valve-interference engines due to the fact that if the timing belt goes bad and snaps you've just totalled your valves completely. It's a very common occurance too because most people don't know the belt has to be replaced every 30k miles I believe. It's a very horrible experience if you're a lucky owner of a 1989 944 Turbo S since it had special Na filled valves that cost about $100+ each valve I believe to replace now.
 

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Ecotec's are interference engines.... a friend of mine had a brand new grand am, at 23k miles the timing chain broke. since it was still under warranty he got a nice long list of parts & labor costs with a total of 0. would have been about $1700 though.

Most older timing belts need replaces at 60k... newer car by law have to be 100k or 105k.... That consumer protection, thank you california. Chains should be checked for wear though... bad things can happen, most just decreased performance, but the gear can lose teeth or if the chain get loose enough it could jump a tooth
 

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neither a good or bad thing,until timing chain or belt breaks then it becomes a bad thing. because piston will hit the valves and most likely cause damage.
 

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It really isn't a bad thing, and not necessarily a good thing. All it is, is just that when the piston is at full TDC, and if the valve were to come down at the moment, it'd hit the piston. But then the cam and crank timing are such that they won't ever touch each other. Thats all it is, just clearance. I think just about any high compression engine runs an interference design because of how close the piston must come to compress.
its not a good or bad thing until the chain or belt in other cars breaks,then it becomes a bad thing because of parts interfering with one another resulthing in bent valves...by the way "usualy" chains are better (longer lasting) on a small car outlasts the vehicule,but not the chev 2.2 ecotech has a chain but is the weakest point in the car. i have a 2005 cavalier and it broke. so i have been doing a lot of research and it seems to be a big problem that chevrolet keeps quiet, some people had the chain break at 70 000 km a belt lasts longer than that !! now i have to find out if the valves are damaged.
 
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