The best way to drain the reservoir and the radiator is to get under the hood with a bucket and a screwdriver. The lower part of this system is a 2" hose that attaches to the bottom of the radiator on the passenger side. This is the fastest and easiest way to "flush" the system and this is the way they do it at the stealership, trust me...
Once you find it (picture shows it from top and bottom) loosen the clamp with your screwdriver and place a bucket right underneath. The one I used fit right in between the floor and the bumper. Once you are ready remove the hose and let the fluid drain in the bucket, you will get about 12 qts of fluid. Take the cap off the reservoir and the system will drain faster
Once it's dry do one more step before putting the hose/clamp back on. pour some of the coolant in a glass and put it back in the reservoir, this will "flush" the lines and radiator a little bit more. Every time I do this I get more debris.
Put the hose back on and use the same clamp, try to put it on where it was and do not over tighten it or the clamp will damage the hose.
Service the reservoir with ONLY MB or Zerex G-O5 coolant. I got mine at NAPA for $10 each. you will need 12 qts of coolant. Buy the 50/50 already mixed if you like the convenience of having the product all ready to go.
I wasn't able to put all 12 qts in the reservoir the first time. Just bring the coolant with you and the first time you drive the car the fluid will work its way into the system. the "low coolant" light may come on, this is normal. Service reservoir next time you stop and the engine cools down.
REMEMBER: Never open the reservoir cap when the engine is hot, wait until the engine cools down to service reservoir. It took me 3 times driving my car before I could put the 12 qts in the reservoir.
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If you drain it from the lower hose, that should drain the block. The thermostat is usually located on the top side of the engine to allow flow through the upper hose when operating temp. is met.
12 qts. removed is quite a good amount.
If you drain it from the lower hose, that should drain the block. .
You said "should" but you don't know. The precodure said to remove the block coolant drain plugs also when doing the coolant exchange. The plug is there for a reason. Take the tranny service for example, on automatic tranny that have the torque convertor, just by dropping the pan and replace the filter does not remove all the fluids. The torque convertor still hold alot of fluid if you don't remove the drain plug on the torque convertor.
Drives: 2007 GL450 2005 C55 2002 C32 sold 2001 ML320 sold
On my 2002 ML320 using the bottom hose method as described, managed to put 11 quarts of the Zerez 50/50 mix back in after draining. I did not measure how much i took out, but assume it was close to 11 quarts based on what i put in. I did have to drive around for a while before the last quart out of the 11 total would go in though.
Thanks for the detailed write up. I just did my radiator flush today thanks to your informative write up and pictures.
Only thing I did different was use MB coolant. The dealer also told me if I am doing this my self to use only distilled water, as tap water contains chemicals such as Fluoride and Chlorine which are not good for the radiator considering it will be sitting there for years. I was actually planning on using tap water before that conversation they had with me. Made sense, so I spent the $3 dollars buying distilled water.