So I've read many of the thread related to changing the coolant. I decided to not use some coolant flush as I was not really having issues with the system, so I just pulled the lower radiator hose off and collected the fluid- pleasantly surprised at how good it looked; no chunks or ugly stuff. Ran the garden hose thru the upper hose until it seems like water. Put the lower hose back on. Put in the upper hose 1/2 gallon of vinegar and filled the rest with distilled water until it started to come out the top exit of the radiator. Ran for 15 minutes with the heater on full, driving around. Got up to 80C on the gauge. Emptied about 3o minutes later via the lower hose removal, and then filled back up again from the upper hose with distilled water. Drove to work 23 miles. Emptied and filled (the same each time- about 1 1/3 gallons) with distilled water. Never gets over 80C- actually cooler than with the old coolant. Drove home and emptied and refilled. Done this now four times and going to do it three more and then fill with one gallon of Zerex G-05.

What should I do instead?

Pull the block drain plug. I just did my '83 and was able to catch 10 quarts of coolant. I'm sure I missed some on the block drain, so the real capacity is a little more.

Agreed.

If you pull the block drain and flush with a garden hose at the back of the head, you can eliminate all of those intermediate flushes. There is nowhere for the coolant to hide.

I'd like to pull the plug but it's hassle to get to it, and it's literally a two minute job for my current flush technique with one tool- a socket driver to loosen/tighten the two hose clamps. The remove the top/bottom hose regime needs no personal clean up or prep besides the bottles of DW in the wagon.

On a side note, why is it running cooler with just distilled water? My drained coolant looked very good and the old hoses were in great shape for what I think were the OEM parts.

On the last drain and fill should I fill with the Zerex only to get the ratio correct?

Pure water is a much better heat transfer agent than coolant. If it weren't for the fish we would never have had to deal with anti-freeze, but that's a whole 'nuther story.

__________________
1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

Ok then, it'll get just the one + gallon of Zerex and call it done.