1992 Legacy Turbo makes very loud knocking noise that fluctuates with engine RPM'S but ONLY when defroster set to defrost or heat/defrost.
Started about 50 miles after dealer did head gasket.
NOT going back- they did plug wires and coil in response to my ?'s about low idle induced vibration that was NEVER an issue before gaskets et al and is still a problem.
Where to start??
Could it be vaccuum related??
What could they have missed (or misconnected) in the re. and re.?
Heater, fan and all controls work fine. No problem on vent or heat setting.
Car seems fine except for this dreadfully frightening knock
I searched but could find no reference to anything similar anywhere.
ANY advise greatly appreciated.
