Hi, bit of a strange problem here. Car wouldn’t start, tried to turn over and then made a screeching sound. Tried new starter motor and same problem. It then started and started knocking sound. Timing was out and knocking was value hitting piston. Reset timing and discovered belt had jumped 4 teeth. Reset timing and back to not starting and  screeching sound. It has a dsg box, could this be jamming? Car currently in with mechanic and this is info he has given me? Thanks 

How unlucky, that sounds rare and hopefully a cheap fix. Let us know what the problem I’d if you get a solution. 

What engine? If the timing has slipped to the point a valve has made contact with a piston it will most likely need to top end rebuild. unless your an experienced tech and can do yourself or the car Is still under warranty it will be a costly repair.

One important piece of information required is what engine do you have fitted?

 

I would have originally suggested a DMF issue which can give a knocking noise and starter motor issues until you mentioned jumping 4 teeth. You don't usually hear the knocking noise for long( if at all)  if you have cambelt failure as the engine usually stops due to lack of compression as the valves are hit/bent by the pistons.

 

How did they check the cambelt had jumped 4 teeth - and have the garage just re-fitted the same one? 

 

Whatever it is sounding expensive. Does the garage know what they are doing?

Edited 28 April, 20206 yr by bigjohn

Are you sure you have given it to a real mechanic as pretty much everything about your post is very worrying. There are so many questions that need answering, we don't know the mileage or the year or the engine, or the service history. 

 

Ultimately, only somebody with the car in front of them can sort this one, if the valves have hit the pistons its a top end off job at the very least.