C240 Coolant/Anti-Freeze Flushing

[EPineda]

Help! I just bought a used 2003 C240 4Matic with over 50,000 miles. While checking the fluids, I noticed bluish/greenish color on the coolant/anti-freeze reservoir as if the original CLEAR-colored MB coolant has been inter-mized with non-MB fluid. I would like to drain the coolant completely and replaced with original MB but unsure where to look for the radiator and engine coolant drain plugs and how many are in this car, as well as the engine air purge(?) plug if any. I done this before on my 300E and it was quite easy. I am just not familiar with this model.

Can anyone please help me by telling me where to look or to find the drain plugs and how many coolant drains I need to open for a complete flush? Is it also recommended to replace the thermostat?

Thanks an awful lot!

[Ali Al-Chalabi]

Not all the cars soming from the factory have the clear fluid. Some of the cars do have blueish fluid in from the factory. Not sure if the formulation is any different, but the color sure is. If it is not clear, that alone does not necessarily mean that it does not have the proper MB coolant in it.

Procedure for a change will be pretty similar to what you did on your 300E. Drian the block, drain the radiator, and refill. It should self-bleed itseld after a refill. Just keep the expansion tank topped off, run the engine, and it should purge most of the air out itself.

[Ethan]

Ali is absolutely correct.

I think at www.mbklasse.com under the username "9KRPM' I posted some nfo on doing a C240 coolant change.

When I did my coolant change on my rwd C240 I couldn't get to the engine drain plugs, though you may have better luck than me.

I ran the heater on high and left those settings when I flushed ( engine off ) and when I purged air bubbles ( engine runnning ).

The radiator drains easily enough, and the refill took one container of MB coolant plus one gallon of distilled water, I mixed both together beforehand.

Ran the engine with the pressure cap off for over five minuted to purge any air bubbles after the refill.

My factory fill was dark blue, then with the added regular yellow color MB coolant my resultant fluid was blueish/green.

You know how to remove the plastic engine cover?

[EPineda]

Thanks to Ali and Ethan for their kind assistance. Both of you could be correct that my C240 might have come from the factory with the bluish color coolant. It sure is strange though. I've had quite a few MB's but this is the first time I'm hearing about colored coolant. Usually, it is clear in a white gallon container. Just playing safe to minimize the possibility of future expensive replacement of a radiator.
In the event I decide to flush out the coolant, is the location of the drain plug on the engine block similarly located at the right side (of the engine block) as in the 300E? How about the air purge plug, is it also on the top of the block?
Thanks again!

[Ethan]

the air purge is the pressure cap on the reservoir.

radiator drain is drivers side bottom, red plastic

[EPineda]

Thanks, Ethan!