I was told years ago, by a mechanic, that my 1968 Buick Riviera’s timing chain would never need to be replaced. I would like to read some comment on the validity of that statement. Thank you.
If timing chains never needed replacement, why do parts stores sell replacement timing chains?
Here’s an example of a stretched timing chain. http://video.aol.com/video-detail/p1010141/3231110855
Timing chains will eventually wear out. If you change oil frequently and use the right grade (viscosity), a timing chain will easily last 300,000 miles in moderate driving.
If all the above are true for your Riviera, you could still be on the orignal timing chain.
However, most timing chains will start to get noisy after 250,000 miles and when that happens they should be replaced. I only ever replaced one, on a 1984 Chevy Impala V8 at about 275,000 miles.
Your mechanic is wrong; no timing chain lasts forever; what usually happens is that the car bites the dust through mismanagement, or gets sold, before the timing belt wears out.
“Never” is a bit strong a word. I don’t think they need replacement very often.
My experience has been that the vast majority of timing chains last through the life of the engine. I think I replaced one in a 65 Ford Falcon, and it was in conjunction with another repair, not the sole reason to replace. However, that particular car and engine has several mechanical issues, as I recall.
On some cars, the cam gear (sprocket) was made from cast aluminum with a plastic overlay covering the gear teeth. This was said to reduce noise…What usually happens, the plastic coating gets brittle and flakes off and the chain starts slipping over what’s left of the teeth. Failure. But some cars were equipped with two steel gears and no plastic coating. These, for the most part, would last the life of the engine which was considered to be 10 years. Your engine and car are now 40 years old. So now it’s just a matter of which major component will fail first. It might be the timing chain, it might be something else…Engines do not wear out one part at a time. If the timing chain is loose and sloppy, the entire engine is also getting loose and sloppy…
I’m sure that the mechanic probably meant one of two things (or both). First, unlike a timing belt, a timing chain is most often not replaced as part of routine maintenance at a specified interval. It is more like a part that you leave alone unless it shows some indication of a problem or potential problem.
On the tail end of that I’d imagine that if something killed an engine on a '68 Rivera it was probably something other than a timing chain - i.e. that the chain would very often outlast the rest of the engine.
If you have some reason to suspect a timing chain problem (e.g. noise) then you should deal with it.