Not even ideas ??
Talking about engine of my G60. I noticed this new effect weeek ago after few cold starts at -10 degrees celsius. Very noisy knocking sound between few second (3-4s). Silent 4 seconds and then knocking few times and silent..knocing and so on... and only at idle. It seems to come from lower part of engine. I've changed rattling water pump and inefficient steering pump about year ago. Oil pump this time ? Any good ideas
Check the main crank pulley. is it wobbling? I too thought I had a bad rod until i found a thread on vortex talking about the crank pulley bolt shearing and causing the pulley to wobble or fall off completley. If your pulley is wobbling when it runs do a search for "crank and bolt" on the Corrado. there are 5 or so threads on it.
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former"
I had the same problem after AC deleting and installing a new H2O pump. the bearing for the pump shaft to the pulley died causing the pulley to wobble like crazy.
We went through everything until we actually saw it. It sounded totally like it was the bottom end and expensive.
I've been told that the bottom ends on the G60s are fairly strong and unless they have been beat on, should last a long time. I'm at 220,000km and have no problems after the new pump got replaced for another new pump.