Sounds like pre ignition at starting - (cranking)
No audible knock at idle or through rev range - loaded or free revving
I did rebuild opti & installed spline shaft wrong which resulted in knock just off
idle. Re installed opti & checked for knock before replacing waterpump!!

Car runs well except for knock at startup.
Is the opti spline still incorrect or can something else cause this pre ignition ?

Thanks
Patrick

 

can you get a sound clip?

 

Knock does not occur at every start - intermittent
Will try & get sound clip.