Changing coolant
 

I want to flush my radiator and change my cooling liquid for my 300TD. Does anyone knows what's the recommended method for a change of cooling liquid?

This is the procedure I use. It is done on a cold engine.

1. Drain fluid. Open radiator petcock and engine block plugs.
2. Remove the thermostat
3. Reinstall the t-stat housing and upper radiator hose
4. Disconnect upper radiator hose at radiator
5. Flush system with garden hose through upper radiator hose until water runs clear
6. Disconnect heater hoses, open heat valve
7. Flush heater core
8. Flush overflow tank
9. Drain as much water as possible from cooling system
10. Siphon water from overflow tank
11. Reinstall thermostat
12. Button everything back up
13. Refill cooling system with specified amount of antifreeze, bring up to level with water, preferably distilled
14. Run car, top off coolant
15. Keep adding water as required every morning until system is topped off.

you forgot to turn the heater on when you start the car after filling, I usually leave the cap off for about 10 miutes with the heat and fan on then cap it drive around let it cool off over night and check again, I don't normally pull the therostate but not a bad idea

http://mb.braingears.com/
 

Mike, the maintenance manuals from the link you provided (http://mb.braingears.com/) are missing pages (coolant change page too) for 300TD and 300D models. Do you know any way in which I could find those pages?

Finally
 

I finally found the procedure at http://mb.braingears.com/123_DISK2/program/Engine/617/20-010.pdf by manually browsing the server :book2:

The problem is that the coolant tank from the pictures and what I have on my 300TD Wagon are not nearly the same. I wonder if whether I could find that drain plug on my cylinder crank-case?!

I don't think the coolant tank makes much difference. The drain is on the right side of the engine (when you're in the car) above the starter, and below/behind the turbo (if you have one). By all accounts, it is a pain to remove. I managed to flush mine without removing the drain, but I did several flushes to make sure I got everything out. Good luck.

How
 

And how did u managed to flush yours? Disconnecting the hoses?

Finally, can you tell me why is it such a pain to use the drain?

I basically disconnected the heater supply and upper radiator hoses and flushed through the cold engine and heater with a hose until the water was clean. Then I refilled the system with water and a flush and ran it for a few days. I then flushed it with a hose again, dumped a couple of gallons of demin water through the system to get rid of the tap water. I refilled with 50/50 mix of MB antifreeze and demin water, leaving the top hoses off as I filled. I ran the engine with the heater on and topped of the coolant as required. Keep an eye on the coolant level for a few days to make sure all the air is out of the system.

It was just difficult to get to the drain plug on my turbo, and I am told it takes quite a bit of torque to remove the drain plug. If you search this forum, you will find several discussions of the best way to flush. It probably is better to remove the drain plug, I just didn't want to deal with it at the time.