1992 Lexus SC 300 belt tentioner going out

Hi ecaterinis1. Welcome to the forum. You are expecting way too much in the way of foretelling the future. There's no way to tell when parts like that will fail. Some failures on some cars can be predicted based on mileage and past history. Timing belts are one example, and GM products have a ton of "pattern failures". But 6,000 miles ago there was nothing wrong with your tensioner so why would you replace it? Also, the bearing or bushing inside a tensioner's pivot is sealed and hidden. The only clue, by looking at it, that it is defective is if the belt is walking off-center or is starting to shred on the sides. When that starts to happen, belt failure is usually only a few miles away, not 6,000.

Very often, when the mechanic IS aware of things to look out for, (Honda timing belts breaking at 60,000 miles is a perfect example), and he recommends preventive repairs so you don't break down on the side of the road, he is accused of trying to sell you parts you don't need. Your tensioner is not one of those parts that can be predicted. The tensioner on my '88 Grand Caravan with 379,000 miles is original. I also have replaced defective ones on vehicles with less than 3,000 miles, so you just can't tell.

To look at it from a different angle, how would you have felt if the mechanic said, "there's nothing wrong with your tires, transmission, belt tensioner, engine, power window motors, etc, but I think you should replace your wiper motor. It's working fine yet but it's going to burn out in 6,000 miles". For that matter, if part failures could be predicted, we wouldn't have need of tow trucks. Just bring your car in for repairs a day or two before the breakdown occurs. Wouldn't that save a lot of headaches? :)

caradiodoc

This is just a guess, but I would expect somewhere between $100.00 and $200.00. My experience is related more to Chrysler products during the 1990s. At that time, a belt and tensioner for my aunt's Dynasty cost a total of $75.00 for parts and labor. A common serpentine belt from the dealer today costs around $40.00 but belts for some engines are three times longer and three times more expensive than belts for other engines. I can't guess on the cost today for a tensioner. Ford's are made of plastic and last as long as you would expect plastic to last in that application. I don't think a typical steel tensioner should cost more than $100.00, but remember, I'm thinking from the 1990s yet. Labor at most shops is approaching $100.00 per hour. It takes less than a half hour to replace a belt and tensioner on OLDER Chrysler products. It's more involved now on almost every brand and model of car and van so you might expect it to take an hour or more. It depends on how hard it is to reach the mounting bolts.

Most shops charge labor according to a "flat rate guide" so they should be able to give you a very close estimate. That guide allows them to charge the same amount of time as any other shop for the same repair. Only the hourly shop rate and cost of the belt and tensioner will vary. Under the flat rate system, if the mechanic runs into trouble with getting a rusty bolt loose, or any other unforeseen circumstances that makes the job take longer, you don't pay for the extra time. On the other hand, if he is very experienced, has a lot of additional training, or has invested in expensive specialty tools and equipment, he might get the job done faster than the stated book time. You still pay the same amount for labor and the mechanic gets paid the same amount, but he can move on to the next job sooner. It's the same as paying ten bucks for a haircut regardless if it takes the barber five minutes or an hour. The faster he works, the more money he earns. The checks and balances is if the barber or the mechanic screws something up due to their haste, they have to do it over again for free until it's done correctly, and you don't pay again. It's in the mechanic's best interest to not waste time AND to do it right the first time.

Caradiodoc