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Several mechanics have suggested that it isn't necessary to replace the cambelt if the car's travelled less than 10,000 miles even if the vehicle is 7 years old. Is there a way to check if it is needed or if it isn't? The vehicle is an Audi A3.

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  • Welcome to Motor Vehicle Maintenance & Repair! Commented May 15, 2021 at 14:12

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Miles driven isn't the only factor that governs the safe lifetime of the belt. They don't put the age condition on the service schedule for no reason - the materials the belts are made of (particularly rubber-based ones) perish and weaken over time. This occurs due to exposure to temperature extremes, to motor oil (and other substances found in the engine bay). Same goes for the metal ancillaries to the belt - the tensioner etc. Sometimes this damage will be visible, sometimes it won't.

You could probably get away for a while longer, but how long is anybody's guess, and you only really know that you've gone too long when it snaps. When they came up with that 7 years figure Audi decided that few enough of the belts would snap before that time that they could live with the ensuing warranty claims for the ones that didn't make it.

Which isn't to say that they all snap/fail after 7 years and 1 day - but that the likelihood of them snapping increases to the point where they didn't want to take that gamble. And a gamble it is - because if it fails then you're going to be in for a big bill. Assuming it's an interference engine (and most of the ones I can think of for the A3 are) then you're going to be looking at replacing belt, tensioner, waterpump, some (possibly all) of the valves, probably some damage to the pistons and it you get particularly unlucky it might even damage the head in the process. If you get extra-special-super-duper unlucky it'll have broken bits off one of the valves and ground those metal fragments into the cylinder walls and at that point the engine is basically so much scrap metal.

Unless the value of the car itself is less than the cost of getting the belt done (hard to imagine in a 7 year old, low mileage A3) then it makes sense to get it done IMO.

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You don't have to do anything, it's a judgement call.

If I remember correctly the service interval for most Audi cam belts is in the range of 70-80k miles, or 5-7 years depending on the engine type. So if you want to or must follow the stated service intervals you should replace the belt.

However, if mechanics with good experience on VW/Audi engines all agree you don't need to replace it yet then that's good evidence you could skip it for now.

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You can do a visual inspection, to look for signs of wear or cracking.

However I have seen belts that "look" in good condition just "fail"...

But given the cost of the damage if it fails then I would get it replaced, at 7 years old I would think it is a good investment.

Had the belt replaced on my car as it is 15 years old - just good insurance.

Your choice on how you spend your money.

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  • What's the best option to have it checked out since I've had 3 mechanics tell me otherwise?
    – Ryan
    Commented May 15, 2021 at 8:28
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    @Ryan what did you not understand in my answer?
    – Solar Mike
    Commented May 15, 2021 at 10:24
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    I agree with Solar but i've seen some belts "set" because they are stationary and under tension so long. They look ok whilst not touched but if you turn the engine over by hand it can reveal cracks you didnt know about.
    – Mauro
    Commented May 15, 2021 at 15:45

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