I just bought a 2007 Toyota Rav4 with 108K miles. I assume the timing chain has never been replaced. The scheduled maintenance in the manual does not mention the timing chain needing replacement at any mileage interval. Does this mean I should just forget about it?
Timing chains are not like timing belts. In most modern cars they will last as long as the car. There is no scheduled replacement for it.
It’s not the timing chain that fails on these engines, but instead the timing chain guides. These plastic guides become brittle over time and start to break off. If a piece of the guide falls down between the timing chain and crankshaft sprocket, it can ramp the the timing chain off the sprocket, and then you end up with a big mess.
Overall, I agree with FoDaddy.
However, since this is a used vehicle, there are many unknowns.
If the previous owner was in the habit of doing a lot of full-throttle acceleration runs, he may have stretched the timing chain.
If the previous owner used “extended” oil change intervals, it is possible for there to be a build-up of oil sludge in the crankcase. Oil sludge impedes the flow of oil to many parts of the engine–including the timing chain, and can severely limit the life of the timing chain.
However, the good news is that–unlike timing belts–a timing chain will almost always give an audible indication that it has stretched. Do you hear a noise similar to that of a chain vibrating against a piece of metal? If you do, that is a very bad sign. If you don’t hear any noise of that type, then motor on with confidence.
Just one other bit of advice:
Unless you can confirm through maintenance records that all required maintenance has been done, up through the major 90k service, then you need to have everything on the 30k, 60k, and 90k maintenance lists done. And, even if the maintenance schedule does not mention it, you do need to change automatic trans fluid every 30k miles.
As others have indicated the timing chain is not considered a maintence item i.e. it is replaced on condition. However, the oil and filter should be changed on a regular basis. If you drive short distances, tow, or do other severe driving, follow the severe oil change intervals. The last thing you want is sludging up of the cam drive system. Also, the Rav-4 probably has a variable valve timing mechanism that does not tolerate sludging.
Keep the Rav well maintained and you will get a lot of miles out of it.
Forget about it.
Just change the transmission fluid(s), spark plugs and whatever filters are due and drive on.