I'm going to go ahead and drain, flush, and refill the coolant. I've read some conflicting statements regarding the removal of the engine block drain plug. Some say remove it, some say don't remove it. Its in a hard location to access anyway. Can I just drain and flush using the radiator drain plug only? Even the tech guy at the MB dealership didn't even mention the engine block drain plug.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

That block plug is easy to get out with a 10 or12 inch extension if you take the aircleaner off the car...

And having done this myself...I recomend doing it...you will see rust and debris come out thats too heavy to exit by other means.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I agree - you'll get a lot out of there, you really should remove that plug.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Ok then, will do. Although, I'm going to have to put it off for now. I had a little leak where quite a bit of the coolant leaked out. I've fixed the leak, but I need to add some green coolant to get me through till thursday, since I can't just add MB coolant to the green stuff that's already in there. Will any "McParts" brand coolant do for now until I can get the proper stuff in?
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

I had an interesting experience with the 617.

I'm in the process of redoing the head. The radiator was drained, the thermostat housing was completely removed.

I'm staring at the return hose to the water pump. The hose is filled with coolant. So, the 617 is filled up to level of the head (lower part) after you have fully drained the radiator.

Got underneath and removed the block plug. About 3 quarts of coolant headed out of the block in short order.

There is no possible way of changing the coolant properly on the 617 without removing the block plug.

Brian, I believe that removing the thermostat and replacing it with the "stuck-open thermostat looking device" that MB describes in their service bulletin on flushing will allow one to use a flushing machine, attached to the radiator inlet somehow and that should do a fair job of getting all the coolant mixture out. I don't know about heavier residue though. I know an Indy that has such a machine but I've never asked how he likes it. I've always drained and refilled 4 or 5 times till the water runs clear.
I've never seen the special temporary thermostat either, has anyone ever used one?

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Plus if you do a citric acid flush you are going to have chunks of calcium and rust floating around in it.....

Take my word on that....I got out lots of that stuff on my W116.

I will be doing my W123 in about a month when I put my block heater into that at the same time.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I would simply add water, there isn't any need for adding antifreeze provided you plan on flushing sometime soon. a 20% mixture will have some anti-corrosion protection left (not like 45% but still ok for a few weeks).
As for the drain plug, I saw one that wouldn't come out even with a 5 ft breaker bar extension, the engine was lifting off the mounts with the force and it was simply stuck! One risks a cracked block if heat is applied unevenly (ie. this is delicate process!)
Just be aware that it might be really hard to get an old drain plug out!
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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

I can only relate to one drain plug. This plug came out with almost no effort. It's quite a bit smaller than the plug for the block heater (which I found laying behind the starter..........apparently some mechanic dropped it in there some time in the past)

I have a suspicion that the struggles are with the larger caps (for the block heater) that sit above the drain plug.

I'd be interested to see if anyone else has difficulty with the 617 drain plug. The threads are very short and they don't seem like they ever would be impossible to remove.

What is the best approach position for a 1984 123 Turbo 300D?
Also, for our 1976 300D , is the block drain plug in the same relative position?

Thanks,
Rich