What causes cambelt jump a tooth?

[Neo Badness]

Had my car in getting a new cambelt at the garage. Have taken it back to them as was seriously impossible to drive throttle cutting in an out and never knowing when it was going to have power, then struggling up hills etc.

They have replaced the ISV with a spare I had saying this has (allegedly) cured the idle/throttle probs.

However, when I called they said that the cambelt had jumped a tooth hence being like a 34hp motor.
Now they fitted they belt etc should they charge me for it?
And also what causes cambelts to jump teeth?

[Cable]

Did they replace the tensioners?

The cambelt should never be loose enough to jump teeth, only risk is when the belt isnt tensioned properly and engine is rotated anticlockwise.

was the problem there as soon as they put the belt on?

[warnesey333]

When I changed the belt on mine the belt slipped a fair few times.

The tensioner wasn't tight enough and like neo says, if its turned anti it will easily jump as its not pulling the longest length of belt its pushing it.

If they've caused the problem, surely they shouldn't charge you for it?

[Neo Badness]

Did they replace the tensioners?

The cambelt should never be loose enough to jump teeth, only risk it when the belt isnt tensioned properly and engine is rotated anticlockwise.

was the problem there as soon as they put the belt on?

Yeah was a new VW cambelt/ tensioner/ waterpump. Taken to VW specialist. Seemed ok initially but has got progressively worse. However I've only done about 200miles max since it was done.

It would imply either it wasn't fitted properly or that the tensioner has failed?

[Neo Badness]

If they've caused the problem, surely they shouldn't charge you for it?

I hope not mate, I took it to professionals as I didn't really know what I was doing. It appears that neither did they

Now to be fair to them they said they would give me an update tomorrow so I will give them oppertunity to make it right.

Cheers for the knowledge though guys.

[Jay]

I'd question them as to how they think it could have happened when they recently done the belt change, then subtly imply it was their shoddy workmanship 

[danny_p]

correctly installed cam belts don't jump teeth : FACT

it was ether fitted wrong or fitted a tooth out

[jezza16v]

Or the key on the crankshaft pulley has failed and let it slip a bit???

[Thom89]

correctly installed cam belts don't jump teeth : FACT

it was ether fitted wrong or fitted a tooth out

Not fact! I could make a list as long as your arm that could cause a cambelt to jump!  thorough investigation is the key here to avoid serious damage
Thom

[Wayne]

correctly installed cam belts don't jump teeth : FACT

it was ether fitted wrong or fitted a tooth out

Not fact! I could make a list as long as your arm that could cause a cambelt to jump!  thorough investigation is the key here to avoid serious damage
Thom

+1 sound advice