OM603 Coolant flush procedure

[speedy300Dturbo]

I'm currently in the process of flushing the coolant in my 1987 300D. I drained the radiator and block, added the flush solution, and then attempted to fill the system to capacity (10 quarts). I only managed to get 5-6 quarts in, and now the level in the coolant tank doesn't want to go down any lower. What gives? Squeezing the upper radiator hose doesn't seem to do much. I recall someone mentioning that it takes some time for the coolant to "sink in" to the system, and it's possible to get in almost 9 quarts before starting the engine. How long should this take? A few hours? Thanks in advance!

[psfred]

That engine holds air forever.

Best way to bleed is to squash the upper radiator hose down, then crimp the small line going to the tank shut and release the upper radiator hose. This will suck a bunch of coolant into the engine. Repeat, filling the tank as necessary, until it won't take any more, then start engine and stand by for the thermostat to open. Tank will suck down, keep adding coolant.

You won't get the whole amount in, but for a flush who cares? When you fill with fresh coolant, expect to have to top off a coupe times over a week or so as the air works out. When the heater core stops gurgling it's full.

The other option of filling through the upper radiator hose works too, so long as you don't pour in too fast so the air can get out.

Peter

[romansek]

Remove temperature sensor on top of the engine where the upper radiator house is connected. The air will have way to escape. When you see coolent flow thru openning install temperature sensor. Problem with air in cooling system will be solved. Good luck.

Roman
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87 300SDL 152K
86 300SDL 212K
86 420SEL 225K
81 300D 139K

[dieseldiehard]

I am thinking "why didn't I think of that?"
Is that the three terminal sensor? I had to replace mine because it went kaput and the fan ran all the time. I also had an air pocket on my '87 300D and never thought to bleed it thru the sensor, brilliant idea!
I also have a connecting plug to feed 12V to the heater pump - OOPS, this is the OM603 (OK I'm tired and its getting late) - is there a heater pump like the W123/126 on this car?
I use that method on those cars to operate the heater pump when flushing the system (all power must be off, as the mono valve goes into rest state that way) and it works. I haven't really read a procedure for flushing the 124 and plan on doing it regularly.
BTW, thsi subject reminds me, I gotta add the RedLine Diesel Water Wetter soon, summer is almost over! The proper way would seem to be draining some of the existing fluid first in order to let the additive go from the overflow tank down into the radiator, then put what was drained out back into the tank, right? I suppose it would take a long time to mix into the system if simply added to the tank.

[romansek]

Dieseldiehard on 300SDL I have two sensors. The three terminal sensor I read on this forum does not like to be washed. I losted two of them on my cars. If your fan work continuosly just unplug conector to the sensor. The second terminal controls A/C. When my A/C stoped working unpluging the three terminal sensor solved my problem.

Roman

[WANT '71 280SEL]

This is a general flushing question. So you added the flush solution and coolant (50/50 mix w/ water) to the tank. (after draining out the old coolant from everywhere of course). Then you can add everything through the upper radiator hose into the radiator? Then, you start the car and let it run until the engine gets up to running temp to open the thermostat? Then you drain all the coolant/flushing agent out of the radiator and the block?
Where is the coolant plug on a 617 motor? I am speaking of my '79 SD. I know there is the big plug where the block heater goes in, but where is the other one?
Thanks
David