I've been plowing through the archives but couldn't isolate answers to these questions.

1) How do you completely drain the coolant system on the M103? I've been refreshing some of the coolant by draining from the petcock on the bottom of the radiator but that won't get all of it.

2) How do you go about flushing the system using citric acid or just plain water? I've always tried to avoid using tap water but I guess that's the only way to flush the system.

Thanks in advance,
Bud