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Repair gone wrong

I recently had the water pump changed on my Mitsubishi Eclipse. The mechanic recommended changing the timing belt. I agreed and a day or two later the repairs were completed. However, about two weeks later, the car was being driven to work under normal conditions at about 35-40 mph and the new timing belt broke causing damage to the interference engine. I had it towed back to the mechanic that did the original work and they diagnosed and verified the timing belt had broken. They stated that the tensioner caused it to break.

My question is this…
Is the mechanic responsible for the damage to my engine as he had just previously replaced the timing belt? Should the mechanic have checked and replaced the tensioner when changing the timing belt?

Yes and yes.


+1. The mechanic should check every part of the timing belt system, including the tensioner. If it broke a short while later, it should have been obvious that it was failing. If you want a new or rebuilt engine, be prepared to go to court. His insurance should cover it, but he might balk at using it.

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If a tensioner was suggested and you turned it down, no liability. I am not familiar with this car to know if a tensioner replacement is SOP or not.

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This is the right answer. If you did not decline a tensioner, then it’s on him.

I do know that some mechanics will not replace the tensioner unless it shows obvious signs of problems. Personally I think that’s nuts - you’ve already done all the surgery to get down to it. It doesn’t cost much more to just replace it, and then you have peace of mind and aren’t risking exactly what happened to you.


I did not turn down the tensioner. It was not offered as part of the recommended repair. Had it been I would have gladly payed the $65 for the part.

I agree.

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Most mechanics I know will turn you away if you decline to replace tensioner. Too much of a hassle for them to deal with.


Your mechanic made a serious mistake. You are not expected to know about things like tensioners and replacing them, the mechanic is the “expert” here. In most cars the tensioners, pulleys and the waterpump are changed routinely when a timing belt is replaced, because the labor for the belt alone is a big item and all those parts are easily replaced when the belt comes off.


Around here, the first replacement typically does not include the tensioner and pulleys. I asked about it when the dealer replaced the timing belt in 2012 on my 2005 Accord V6 at 105,000 miles. They said they could do it, but normally didn’t. They would inspect it and the seals when they got into the job and then call me if these teams needed replacement. The other two shops I got estimates from didn’t normally do it either.

I’m not so sure the tensioner failed. Did you see the “failed” tensioner?

This is a tough one. It’s entirely possible – maybe the proper word is “conceivable” – the existing tensioner tested ok but decided to fail at that moment, and it would have damaged the engine whether or not the timing belt had been replaced. The only thing that would have prevented this then would have been a shop policy to replace the tensioner along w/the timing belt as routine practice.

Here’s one bit of data: I’ve replaced the timing belt on my 200K miles Corolla 3 times over the years, and on my VW Rabbit twice, and never replaced a tensioner yet. Still has the original tensioner. It has always tested good, no sign of worn out bearings to date. Probably the best advice is to have the situation assessed by another shop. They might be able to spot what caused this.

Absent that, OP may never know what happened. If allowed to venture a guess, I’m thinking along the lines of @insightful above, something about the timing belt install job went amiss. Admittadly just a guess. But having replaced timing belts a few times before, I know there are some mistakes that would be easy to make. The tensioner bolt wasn’t tightened properly, belt pulley’s got installed incorrectly, some kind of belt alignment piece, spacer, etc got lost during the install, etc.

They told me the same thing on my Acura. I told them to replace them anyway. They ignored me. I made them do the job over again. I don’t screw around with that - they’re asking me to have a part go 210,000 miles when if it breaks, it takes the engine with it, and they’re right there staring at it after $1,000 worth of labor to tear down to it. I don’t think so.


Yes, any tensioner or idlers should always be replaced during any timing belt job.

This is a mechanic error.

Now, the second part. This is an interference fit engine; meaning the engine will suffer damage if a timing belt breaks for whatever reason.
The intake valves in the cylinder head will hit the pistons and bend the valves. In rarer cases a piston may crack, rod may be bend, or rod bearing will be damaged. In most cases at a minimum a cylinder head repair will be needed.

Odds are he will balk at covering this for you no matter no matter how obvious the fault is.

I see from the previous quotations it may not be an obvious fault, sure Senior Safety would always replace the tensioner, but it does not appear to be a standard, and yes I would love my mechanic to be Senior Safety, but in the real world Senior Save a buck often rules.

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I’ve had people approach me about various repairs and who want to skip a part or process so they can save a buck. My answer has always been take it elsewhere because I’m not shortcutting anything.


I called the local Mitsubishi dealer and asked if the it was standard to change the tensioner when installing a new timing belt. He stated that they highly recommend changing the tensioner along with the belt and in fact their timing belt kit comes with a timing belt, water pump and tensioner.

I originally took the car in due to a coolant problem in which they ended up having to replace the coolant pipe and water pump. This is when they recommended to change the timing belt. It never had a problem with the timing belt before they changed it.

They say the belt broke because of the tensioner[too tight from whomever did the last timing belt a few years ago]. They also had a tensioner bracket bolt break upon the 2nd reinstall of the timing belt.

When they installed the new timing belt the first time, should they have had to adjust the tensioner? It seems to me that in order to take the old one off one would have to loosen the tensioner and then readjust/tighten it to fit proper with the new install. After fixing the tensioner bracket bolt, and replacing timing belt a 2nd time, why would the mechanic still not say anything about a installing new tensioner?

Say what?
These guys are bozos. Once this gets resolved, I recommend you seek out a new shop to patronize.

Does a tensioner need to be adjusted on every timing belt install regardless of the type of tensioner or whether it is new or old?

Yes, as a minimum. In the case of the Mitsu Eclipse, the tensioner is basically a pully assembly that includes elastomerics (see attached link). In this case, it should be changed. The rubber breaks down over time.

Their trying to blame whoever changed the belt years ago is blasphemy.