vectra - vectra di
my vectra 98 2.0di has recently started to make a funny noise when the ignition is turned to the first stage. it sounds like somebody knocking once on the bonnet. the fault is obviously engine related (pre start) but the weird thing is that it can only be heard from inside the car. open the bonnet and turn the ignition and you can barely hear it in the engine bay. but the noise is definetely in the engine compartment.

anybody experienced similar or any idea's what to check.
i think it is related to the preheat system purely because with the ignition on the first stage preheat is the only thing becomes active.

cheers
 

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