Car Doctor Q&A: Who’s At Fault When Auto Repairs Go Wrong?

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This week, AAA Car Doctor John Paul fields a question about a timing belt that failed just months after replacement. Who’s at fault, the car owner or the shop?

Q. I took my 2000 Mazda 626 into a shop to have the timing belt and water-pump changed. About a month after the belt and water pump were changed, the car started running rough. I took it back to the shop and asked them to take a look. They told me it just needed new spark plugs and they replaced them. A month after that, my car died on the road and wouldn’t start.


When I had it towed back to the shop, it appeared that the timing belt frayed and had broken. When this happened it damaged the valves and they also told me that the cylinder-head was warped due to overheating. They told me this happened because of a faulty timing-belt tensioner. My question is can a warped head cause the timing belt and tensioner spring to fail and who is responsible?

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A. The repairs that were performed were completely related to the failure of the engine. Since only a couple of months have passed since the repair, I would say the shop is responsible. In my opinion, considering the age of the car, the shop should have replaced the belt tensioner as part of the service that was performed. In fact many parts manufacturers sell a timing belt kit that includes the water pump, timing belt and tensioner as well as any gaskets, seals and pulleys.