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Timing Belt Jumped 1 Tooth

jvs007

By jvs007,
in General Maintenance

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jvs007 Rising Star

jvs007

Posted
Posted (edited)

hey ppl, got timing belt, water pump, idler pulley, tensioner and cam seals changed on my r32 gtst, mechanic put it all in, test drive went good, on the way back heard a 'crack' type noise and then engine started coughin etc.

pulled it apart found belt 1 tooth out.... how does this happen ???

i trust the guy enough when he says he checked everything, has this happen to anyone before

result is loss of compression on piston 2 and 6, head comes off, finds out 2 inlet valves on 2 and 6 bent ! doh !!

thanx in advance ppl

Edited by jvs007
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Fry_33 Proficient

Fry_33

Posted
Posted
hey ppl, got timing belt, water pump, idler pulley, tensioner and cam seals changed on my r32 gtst, mechanic put it all in, test drive went good, on the way back heard a 'crack' type noise and then engine started coughin etc.

pulled it apart found belt 1 tooth out.... how does this happen ???

i trust the guy enough when he says he checked everything, has this happen to anyone before

result is loss of compression on piston 2 and 6, head comes off, finds out 2 inlet valves on 2 and 6 bent ! doh !!

thanx in advance ppl

The only real way a belt can jump is a tooth is from lack of tension or incorrect alignment to start with. If the tension is correct then the teeth stay in mesh with the sprocket. Which belt did you install? Did it have the timing marks on it so that it is easier to align? Hopefully it gets fixed well and you have no further problems.

Jmaac Proficient

Jmaac

Posted
Posted (edited)

When u install the timing belt and lock off the tensioner one side is actually tensioned more than the other, and this uneveness causes it to move one tooth on startup. Sounds like your mechanic put it on and didnt turn the motor over to even out the belt tension out before checking the alignment of marks (lazy). I found in many old RB30s that I had to line up the belt with one tooth out up on the cam for it to line back up properly when the tension became even

Edited by Jmaac
Fry_33 Proficient

Fry_33

Posted
Posted

It will probably just come down to how it was installed as Justin has said. The installation of a timing belt is pretty basic but you just have to take your time and make sure it's done right. It basically consists of just removing everything until you can get to the belt. Take off the old one, replace idler and tensioner and put the new one on with all of the marks in the right place. You then rotate the belt around two or more times and while there is still some tension on the belt tighten the tensioner. Then put everything back together. This is a simplified way of how the manual says to do it. You need to rotate the belt around so that the teeth of the belt mesh into the sprockets otherwise you get the situation explained by Justin.

Good Luck

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