Vectra pinking after snapped timing belt repair.

I recently was unfortunate enough to have my timing belt snap on my

1999 2.0 16v Vectra, and I have taken the car in for the major repair, head, valve sets, timing pulleys, tensioner, belt etc.

Just got it back yesterday, and the car appear to drive fine except that I have discovered I am now getting a "rattle" on hard acceleration. This mostly occurs in 2nd gear, but can happen in 1st and 3rd. The sound comes from the offside, and eventually goes as speed increases, or if I go easier on acceleration. This never occured prior to the belt snap, and I am wondering what this is most likely to be? I am thinking probably pinking, but I have been offered other suggestions of stretched auxilary drive belt, or tensioner issues. Trouble is I wouldn't know exactly what symptoms these other suggestions would appear as.

I will probably go back to the garage that did the repair, but I'd like to have some idea of what it might be, so that I know they'll address it. Any ideas?

Unfortunately I'm not particularly expert on car repair, so any advice in lay terms would be gratefully appreciated.

Thanks very much Paul

First thing I would make sure of is that all exhaust heatshields are secure and not cracked or broken. The rattling noise that some of these make when they start to work loose can sound very much like pinking.

If the heat shields are OK, and if the engine is definitely pinking, then there could be a problem with the knock sensor. I would expect the engine management light to come on if the sensor was completed disconnected, so the wire may have been kinked and as such have anintermittent open circuit in the cable, or the plug may not be pushed home fully. This sensor is located at the back of the engine, in the middle of the cylinder block, underneath the inlet manifold. The plug is connnected underneath the black plastic trunking the runs the wiring loom across the injectors, between 2 & 3 cylinders I think!

HTH

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