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How many miles did you get until your timing belt failed?

Yes, (Subject) that’s the question for 2004 to 2006 Tundra trucks. It may be that newer Tundra trucks don’t have the problem in some way. What damage occurred?


I think you will find nearly all of us will change the timing belt when specified by mileage or time, so finding someone who actually had one fail would be rare for most folks here.

Go to web site for info on timing belts for '04 - '06 Toyota Tundra trucks. My '01 Sequoia has a timing belt. I got it changed before it broke at the 90K miles as recommended by Toyota.

In the gates site it will tell you if the motor has a belt or not. It also tells you if it is an “interference” motor or not.

An interference motor suffers extensive damage if a belt breaks. Valves collide with pistons, breaking and bending values, breaking pistons, damage to head, and cylinder walls in block can also occur. Repairs will cost several thousand dollars, sometimes it means a change of motors.

A non-interference motor just stops running suddenly, but isn’t locked up. There is no damage to valves and pistons. Repairs costs are for a new belt, and other items such as a water pump and tensioner which are often replaced with a timing belt; about $600. Other costs are the tow, and any damage due the stopping whereever you happen to be when the belt lets go; ie in the passing lanes of a busy bridge with no place to pull over.

Why are you asking? Did yours fail before the replacement interval?

This is not a contest anybody would want to win. It’s like asking “how many miles did you drive without changing your oil before your engine expired?”. The winner loses.

The truck is at 94K miles, and I’m trying to sell it. Judging how to deal with the sale with that problem hanging around is troublesome. Personally, I’m a big fan of data collection. There is none in this case. Maybe the mentioned above may offer a clue.

However, my contention is that the auto/truck dealers are depending upon fear to sell a replacement to some degree. They reveal no data. Certainly the recommendation of 90K is helpful, but they must have some idea how the probability of failure increase above that. I would think the mfger would protect himself from an “error” by at least knowing a satisfactory upper bound, so he didn’t have vehicles failing left and right.

This is all a matter of fairly simple statistical analysis. I’m sure they have done it, but the consumer doesn’t have any knowledge of it. It would probably take some independent agency to collect sufficient data. Anyone want a new career and job opportunity? :slight_smile:

Very interesting information. I’ll take a look, but see my response below about a needed “statistical analysis”. I had a timing chain failure on a 1985 Camry decades ago. I was stopped at a light. :slight_smile:

I think newer Toyota trucks may have something going for them along the lines you mentioned.

The trouble with using statistical analysis on something like this is that, to your buyer, the only data point that matters is the truck you’re trying to sell him. If the average truck can make it to 110k miles on the original timing belt, that’s really neat, but doesn’t help me much if mine is a statistical outlier and breaks at 94k. So putting myself in the position of a potential buyer of your truck, I don’t care about your statistics. I care about whether you followed the scheduled maintenance.

Most people who know enough to ask about timing belts know that the 90k (or whatever) mileage recommendation is one with a safety margin built in. That’s as it should be. Note that it’s called a safety margin, not a cheapskate margin; you change it as scheduled so that you don’t go in to that safety margin.

Having just come off of a T-belt job for someone else who had gone slightly into the “safety margin” and having seen the condition of the belt, I’m still an advocate for not getting into the safety margin.

Also as a potential buyer, I’m going to see that you decided to comfort yourself with statistics as an excuse for not changing the belt on time, and I’m going to assume that you did the same thing with all the other things you’re supposed to do with the car. So now I’m assuming that you failed to break the engine in properly, and you didn’t get the oil changed when you should, and you didn’t change the transmission fluid when you should, etc etc. I’m going to assume that you’re trying to sell me a ticking time bomb, and I’m going to go give my money to someone who did what the manual said they were supposed to do.

Because statistically, a poorly-maintained vehicle will have more problems than one that was properly cared for.

One of the regular contributors here used to work at a company where they made and tested timing belts. He said some would go out to over 400K miles before they broke. He, in no way, implied that it was OK to go beyond the manufactures recommended replacement schedule.

If I told you I had the same truck as you and I went 94K miles before changing the belt, how would that help you?

Some cars chew up belts faster than others. How lucky do you feel?

There is data, you likely will never see it. Mfg’rs run the motors on test stands and record the results. My 1st job post college was with the mfg’r of timing chain for GM. I’d bet the testing is similar for timing belts.

In our tests the mfg’r accepted 10% early failures, and about 90% failures after the designed replacement interval. Some chains simply never broke, but most did by 2X time the designed life.

Therefore my educated guess for a Tundra (with 90K recommended replacement interval for the timing belt) is about 5 to 10% fail before 90K miles, making this a relatively rare covered under warranty repair. Between 90K and 120K miles about another 10% fail. After 120K miles the failure rate will get much higher. By 200K miles about 90% fail. All this is a guess, but again the mfg’rs know the stats, but the buying public won’t get that info.

How much of a gambling man are you? At 94K you haven’t gambled in the high stakes zone yet. At 110K and up then you are getting into a high stakes game. That’s because the cost of a failure is high. My Sequoia is an interference motor and I’m pretty sure yours is too.

The daughter owned a Ford Escort that didn’t need timing belt service until 90,000 miles. But hers snapped at 70,000 miles. It happened as she was accelerating from a stop. Luckly it had a non-interference engine.


I you avoid vehicles powered by engines that employ a timing belt, you avoid all of these concerns…

Car makers who still want to be in business 5 years from now have seen the light too…

Great posting, Shadow, and I agree with you.

I’d rather buy a vehicle with a timing belt that I can change…then buy a vehicle with a chain…but is so unreliable that I have to spend weekends working on it just to keep it running during the week so I could go to work (which is why I sold my last GM product).

Even if you could collect up enough empirical data to be statistically significant, it would likely be useless because there are far too many variables involved and most people aren’t aware of what they are and if they even apply to their usage patterns.

The engineers most certainly employed a HALT life test method to determine worst case MTTF. They know what factors contribute to degradation and they maximize them during testing. Then a “battle” ensues between marketing and engineering to determine the advertised change interval (which is likely longer than the engineers wanted it to be).

The factors that contribute to belt degradation will vary in magnitude by region and usage. For example, heat is a known degrading factor. Year round operation in Phoenix, AZ is going to be vastly different than someone in Refridgerator Falls, MN :slight_smile: No way the mfr is going to list all of these factors so you can determine that your particular situation warrants a belt in 210k miles vs 90k miles. First of all, they didn’t test every combination of factors and secondly, even if they did it would be confusing to most consumers.

Where do I look on Gates? Do I need to join, search (timing belts), or look in a specific section?

Once one derives the probability distribution function, it is either well known or derivable from the data, one has probabilities to look at. They are very useful. Without some solid evidence of the condition of the belt, I’ll stick with probabilities.

“Also a potential buyer…” Wrong assumptions. Well maintained. In this case, it’s a coincidence the need to sell the truck occurred around the 90K. If I were to keep ownership, then I would very likely be considering the belt change.

See my comment about the pdf just posted. I have seldom seen in reliability theory any need to use many variables on something of this type. I would guess, it’s been a long time since I’ve done this sort of stuff, that it’s a simple exponential. There are a multitude of such distributions that could be used. I seriously doubt a mfg is going to play around with multivariate distributions.

BTW, I would not attempt to get into statistical methodology to sell a vehicle. At most mention a margin or error.

I’ve never had a timing belt failuyre, but my neighbor had hers fail on a VW Passat at 58,000 or so, just before the change out mileage. The dealer gave her a hard time, citing “abuse of the vehicle”!!!

She vowed NEVER to look at another VW and has been driving Hondas ever sice.