I'm in the middle of flushing my coolant right now on my 1988 300e (m103) and I've run into a problem. So far I have emptied the radiator and expansion tank wih the radiator drain. Right now I need to drain the block but the drain plug is REALLY stuck. I can't get enough leverage on it because it's pretty tight in there and I don't want to go spraying wd-40 all over my engine.

The plan is to use the degreaser and citric acid and then flush. All of this seems necessary because the coolant that came out of the radiator was VERY dirty.

Anyway, I'm thinking right now that I will fill up the expansion tank with plain water, then drain the radiator again after running the engine. I want to continue this until it runs clear. Is there any problem with this besides taking a very long time?

Can anybody think of a better way to do the flush or to get the drain plug out?
Thanks for your time.

Peter

1988 300E
1988 420SEL