the cam belt tension spring on my premacy 1.8 snapped and caused the inlet and exaust cams to slip 9 teeth, luckly the valves did no hit the pistons , but they could have, costing me dearly.
mazda know about this problem and have sent a technical bulletin to their dealers
it says the spring should be checked at 54000 miles,when the cam belt should be changed
but mine snapped at 49000 miles
the spring snapped because the small plastic gromet in the cam belt tensioner had worn away
causing the spring to rub metal to metal
so change the tensioner and spring when you change the cam belt to avoid a large cost and being towed to a garage when you break down it the middle of nowhere
the part mumbers are as follows
1.8 engine fp01 12 700a tensioner
2.0 engine fs01 12 700b tensioner
fs01 12 711 tension spring

 

this spring is also fitted to the mazda 6 and can cause the same problems