Timing Belt Question

Is there a way of telling whether a timing belt needs to be replaced besides the miles on the car? It seems like there should be a way of diagnosing such an expensive repair, but I haven’t been able to get the same answer from any two mechanics.

Not really. A timing belt can look perfectly fine on the outside. But what can’t be seen are the reinforcement cords inside the belt. And it’s the failure of these reinforcement cords that causes the timing belt to fail.


A timing belt isn’t really an item to think of as a “repair” - at least you hope not.

It is a basic maintenance item - like oil changes. Follow the manufacturer’s recommended replacement intervals. In terms of consequences, the alternative to that ranges from bad to really disastrous.

We just had a post on this; no, there is no reliable way of telling that a timing belt is going bad, or when it will fail. There is a time and mileage figure in your owner’s manual or you can get it from the Gates website, which lists belts for nearly all cars that have them.

There is no real definitive data on how long they last. The replacement interval is a good guide which is both miles and time(whichever first).

It is all a balance on how much risk you are willing to take if you are educated on the consequences if it snaps.

My sis in law is running around in a Jetta that needs a replacement. She is “risking” it as the car is already in need of repairs/maintenance besides timing belt that exceed its value. She got differing opinions too. I think she also gave up on changing oil 6 months ago too, as the vehicle will not pass emissions.

The way to avoid these problems is to ask the salesman at the time of purchase “Does this car have a rubber timing belt?” If the answer is yes, then ask “Does it have an interference engine?” if he says yes again, walk away and find a car you like where the answer to at least the second question is “no” and hopefully BOTH questions are “no”…

If everyone did this, rubber timing belts would soon be a thing of the past…

Do you know if a 2000 Lexus RX 300 has either of these? Thanks for the feedback. I appreciate it.

Having a chain with a interference engine is going to cost you a LOT more then having a timing belt…unless you never keep your cars past 200k miles…If so then a chain is definitely cheaper.

Lexus V6(yours) is an interference design with timing belt.

Only a small minority of auto owners think about 200k+ ownership.

At least 150k ownership is starting to become more standard, they should create a better timing belt design to last the 150k interval.

It’s got a timing belt, but the Gates lookup doesn’t say interference.

Only a small minority of auto owners think about 200k+ ownership.

Yup…I agree…but those of us who do…a timing belt for a interference engine makes more financial sense. Every vehicle I’ve owned with a chain…the chain had to be replaced <250k miles. And chains can be very very expensive…especially if you have to pull the engine to drop the oil-pan.

Your Lexus is due a timing belt change based on time — 8 years (96 months). The time (as well as mileage) intervals are stated in your scheduled maintainence booklet, or the owner’s manual.

Actually, sometimes there is a way to determine whether or not a timing belt needs to be replaced, besides miles on the car. One time, I removed the upper timing belt cover on an older Ford Escort. I found the belt had in fact lost about two rows of reinforcement cords. I don’t know how many rows of reinforcement cords there are, but about one third of the belt was gone, and only two thirds of the belt remained and it was pretty well shredded with cords sticking out everywhere. At that point, I was fairly confident that it was, indeed, time for the belt to be replaced. Even though it was still running fine. So barring a very (visibly) obvious worn out and shredded belt, I guess the other way of determining it’s time to replace the belt is when your on the side of the road with bent valves and holes in your pistons. Long story short: NO. Change the belt.

You say the timing chain on all the cars you have owned have needed replacing before 250k miles. Using a 60k recommendation to change the belt that many cars have you would be on your 5th belt by then. Also, timing chains say goodbye they get noisy and start slapping the case before they break but belts turn your engine to junk without warning.

Using a 60k recommendation to change the belt

Where are you getting the 60k recommendation for timing belt change??? Hasn’t been that short of an interval in 20 years. Wife’s 96 Accord and my 90 & 98 Pathfinder had interval changes of 100k miles. Most other vehicles I know of that have belts…have a recommended change of around 100k miles.

Also, timing chains say goodbye they get noisy and start slapping the case before they break but belts turn your engine to junk without warning.

Yes they start to make noise…And chains don’t have to break to cause problems…If they slip (which belts rarely do) then you just lost an engine as the piston slams into the slightly opened valve. I agree belts break without warning…however…very very rare do they break BEFORE the recommended interval change of 100k miles. Change the belt per manufacturers recommendation (usually around 100k miles) and you’re fine.

I’ve had noisy chains on older cars that had over 200k miles on them…but I’d usually just ignore it. But with an interference engine when the chain starts making noise…you should replace it ASAP…at a cost of $1500+.

The last part…Since replacing a timing belt is a LOT less complicated then replacing a chain…if you have a little bit of technical car experience you can probably change a timing belt in a afternoon. A chain…most novices will balk at it. I replaced the chain on my 74 Chevy Luv (Made by Isuzu). To remove the chain you had to drop the pan. To drop the pan you unbolt the engine mounts and jack up the engine about 5" so you can maneuver pan out. Remove the valve cover. Then remove the upper and lower timing chain covers…And as long as you’re replacing the chain…might as well replace all the guides and the gears (3 in this engine). And as long as the pan is dropped…clean out the screen (or at least check it) of the oil pump pickup. Scrape all the old gasket material off…etc…etc…etc…needless to say…A LOT MORE INVOLVED.