Here's what I gather from my haynes manual and searching the site, couple of questions at the end.

Protocol:

With cool engine, open rad drain at bottom, drain fluid. Open engine plugs drain here as well.

Fill through expansion tank with hose water.

Run engine with expansion tank cap off until engine goes to first temp reading all the while adding water as needed with heat on full. When first bar is reached put cap back on and run engine for two more minutes.

Drain system as described and refill cool engine with proper mixture of antifreeze and distilled water.

Couple of questions: from searching on this it seems like there is a major concern that cool antifreeze will come in contact with a hot engine block and that it will do big damage. How exactly is this avoided, my impression is that as long as the engine is allowed to completely cool between flushing and draining that there should not be a problem… I don’t know and need to know what you could do to screw the process up and cause major damage. Secondly, I plan on changing the thermostat as a preventative measure. Is there anything else that I should swap just as a throw away part on a car with 190k (when doing this for the first time in who knows how long. Certainly not since I got the car two years ago I know that much). Third, there was also this issue that I saw when searching that said you can introduce air pockets into cooling system if things are done improperly so how exactly is this avoided. Lastly what does heat on high mean? Is that just highest temp highest fan setting or do I need to throw on the defroster or something else in addition?

Thanks for the help,
CDT

__________________
2002suzukiGSF600S
1985 190e 2.3

I'm no Tech expert by any stretch but here's what I did on my 91 190e 2.6.

As a preface, my benz (just bot) had the bright green stuff and had a lot of brown rust particles suspended in the coolant. It seemed appropriate to do a full fledged flushing of the system.

1. With cool engine, drain coolant at rad and engine block plugs. I have one engine block drain plug which is a bear to get to even under the car on your back. Closed plugs.

2. Removed the thermostat and reinstalled the tstat housing cover.

3. Filled with water thru the expansion tank. Put on tank cap.

4. Ran the engine for 10 minutes with heater on and fan on high.

5. Waited till next morning, guareenteeing engine was cold and repeated step 1.

6. Reinstalled t-stat.

7. This time added Zerex Super Flush and filled with water thru the expansion tank.

8. Ran the car for about 5 days totalling about 6 hours normal driving. Checked the expansion tank every morning and added water as necessary to fill line.

9. Drained car again at rad and closed plug.

10. Installed Prestone flush kit unto heater inlet hose and flushed system as per instructions out thru expansion tank until water was clear.

11. Drained rad yet again, closed plug.

12. Installed new t-stat and upper heater hose (as original felt mushy).

13. Filled with Zerex G-05, took like 3 qts. Installed new expansion tank cap. Ran engine for 10 minutes with heater on high again. Let car cool for about 3 hours and topped off with more Zerex.

I checked the coolant level for the first few days afterword and added as needed - I didn't have to add much.

I recommend new tstat and cap - both mine were suspect and using either Zerex G-05 or the Mercedes coolant.

HTH


Doug Stang