m103 Coolant Flush
 

Hey all,

Any pointers on how to do a good coolant flush? I'm thinking open up the block and rad drains and stick a garden hose in one of the heater hoses until it runs clear, then let it drain and refill with 50/50 of distilled and the good MB stuff. Does this sound about right? I don't need to do any kind of detergent wash, I don't have oil in the system. Just need to get rid of the incorrect green coolant;)

I forgot to add, where exactly the m103's block drain?

There are block plugs on each side. I just unscrewed the one that is on the passenger side underneath the manifold and did the radiator drain on front right bottom of the radiator. You should by the Prestone Flush Kit and install on the driver's side heater hose that connects from the firewall down to the rear engine block. You can leave it installed after you are done.

Thanks

Try a citric acid flush, you'll be suprised at how much gunk is released. Buy citric acid at the pharmacy.
When you refill, put the car up on jackstands or ramps and s l o w l y refill with the breather cracked on the t'stat housing.
This is all laid out in the FSM.

Here is the method I use for a good coolant flush.

1. Drain fluid from radiator and engine block
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. Run engine for a bit during flushing to get the fluid from the water pump and other dead spaces.
10. Drain as much water as possible from cooling system
11. Run a shorter flush with distilled water to displace the tap water
12. Siphon water from overflow tank
13. Reinstall thermostat
14. Button everything back up
15. Refill cooling system with specified amount of antifreeze, bring up to level with water, preferably distilled. The amount of antifreeze you need can be calculated from the published cooling capacity for your vehicle.
16. Run car, top off coolant
17. Keep adding water as required every morning until system is topped off.

At the end when you fill it back up, be sure to burp it properly as you don't want air bubbles in the cooling system. To do this, put the car up on ramps, run it with heat full blast to make sure it circulates through the heater core, and keep refilling until it is full. On my 300E I found it easiest to use the bleed screw on the top of the thermostat housing to bleed the system, although it was quite messy (get a nice big bucket).

Thanks for the great tips everyone! When I do the flush I'll set up a post with the results so I can let everyone know how it worked!