Hi, my Mazda 323F (99, 74K miles) has just had a snapped timing belt, cam shaft and one of the rockers has smashed. Don't know what the damage will be to the valves etc as it's still on the way to the garage where a new timing belt was fitted less than 12 months ago. I've done 18K miles since the timing belt was fitted and had the car serviced. I broke down 150 miles from home and had a garage there look at it, they said all the tensioners, water pump, fuel pump were running fine and can't understand why the belt would snap unless it had been over tensioned.
The Garage that did the timing belt (and all the services since I've had the car) state that they've never had a timing belt snap before and will send it away to find out why it happened, they also stated that they use very accurate measuring equipment to check the tension on the timing belt (sorry I'm not a mechanic!) but I guess the tools only as good as the person using it.

The timing belt is made by ADL who apparently only have a warranty for 12 months or 12k miles! The belt has a very unclean tear diagonally across it, the layers of the belt haven't started to come away. The garage that did the timing belt also stated that a stone may have got in and caused the damage but the cover looks good to me and whilst it's not airtight it's certainly good enough to stop and stone getting in.

ANy help or opinions appreciated as I get the impression from the garage that looked at the car when it broke down that it's been over tensioned and I get the impression from the garage that did the timing belt that they've fitted it correctly and something else is to blame. To be fair they haven't looked at it yet but they seem to be setting everything up for "it's not our fault" line.

 

Do not believe I have ever seen a specification for timing belt tension so don't know what kind of 'accurate equipment' could measure it. The timing belt snapping is one thing but what about the camshaft and smashed rocker??? When a belt breaks it simply breaks and you stop moving and get towed to shop to have another put on. The engine should be clearanced so valves should be ok unless UK engines are different than US. Find out more about this camshaft problem and rockers. Overtightening of the front cam pulley bolt can absolutly cause the front of the cam to snap off.

 

Thanks babyhuey, neither can I? The valves and piston heads were all fine, it's had a new set of rockers/followers fitted along with the cam shaft and a cam belt kit (including hydrualic tensioners). I've got my car back but at expense and I'm still scratching my head to whats gone on. The garage think that the belt has snapped due to a stone or something but how it's got in I've no idea. I've kept the old belt just in case, does anyone know of any company in the UK that will test the failed cam beltto find out why it snapped?

THanks