Timing chains, not belts -- to change or not to change?

my 2002 RAV4 with 130k miles has a timing chain, not a timing belt… everything on this car works so well, and is so reliable, is it unreasonable for me to ignore changing this chain for awhile? for how long? I hate to start a needless major mechanical “repair” fearing I’ll get some “car guy” (uh-oh) who doesn’t know what’s he’s doing to screw up something that’s working well… I don’t think there’s any way to just “check” the chain easily, or know if it’s about ready to give out…

There are exceptions, but as a general rule, timing chains are good for the life of the car.

A timing chain is made of metal, is very strong and lasts a long - LONG time. A chain can wear prematurely if a motor does not get clean fresh oil as it should with scheduled maintenance. If you’ve taken reasonably good care of your car the timing chain should be fine.

The symptoms of a worn timing chain is a “slapping” metallic noise in the engine. That is caused by a chain that has stretched and the system that keeps tension on the chain has reached its limit of travel. A chain that is loose and making noise can cause the timing of the valves to skip which can result in engine damage.

Do you have a mechanic telling you the timing chain is shot? Is there noise in the engine? Some cars have a system the automatically takes up the slack in a chain as it wears. Other cars have an adjustment that needs to be done by a mechanic. Perhaps you are being told your timing chain is due for an adjustment, which is a whole lot easier and cheaper than replacement.

Most decent OHC engines use roller chains, running in oil, which will last longer than the rest of the engine. Why do you feel you need to mess with this? “If it’s not broken, fix it until it is”…

Uncle, that’s a very complete, thoughtful response. Thanks. I am a regular “maintainer” and have heard no noises as you describe, nor is anyone saying to make a change or adjustment. I just know that many mechanics say that those with timing belts instead of chains are told to replace regardless of whether there are any clear indications of problems. I’m going to leave’er alone for now. Again, thanks for taking the time to reply.

lenjack, thanks for your prompt response. I’m with you on this one. Hoping the chain and the car will outlast me.

Timing chains are meant to last the life of the vehicle. Even when they or their corresponding parts wear out they’ll start making a clackking noise long before breaking. It sounds kind of like a collapsed lifter.

The only one I ever had to change was on my '89 Toyota pickup…after 200,000 miles. The rest of the pickup lasted another 138,000 miles with no major work.

Over time, timing chains can stretch, even though they’re made out of steel. And I’ve seen cases where a stretched timing chain was able to be removed off the crank/camshaft gears without removing neither. This isn’t timing chain failure but timing chain wear, and effects the engine performance.

Then there are timing chain systems that use plastic teeth on the camshaft gear. In these caes, it’s not the timing chain that stretches/wears out, but instead the teeth on the cam gear come apart and then the timing chain jumps time.

Then there are timing chain systems that use timing chain tensioners/guides. These systems have friction surfaces made from plastic that the timing chain rubs against. When the plastic friction surfaces wear out/come apart it cause the timing chain to jump time.

So it’s not as cut and dry on how long a timing chain/timing chain system will last on todays vehicles as it used to be. But I’ve replaced stretched timing chains on American V8’s with just a little over 100,000 miles on them.