You MUST use distilled or deionised water. Benz insists on it in ROW. The is no reason why the US should be any different. Variable water quality can destabalise the entire coolant package.

I thought the coolant was a pressurized system, so it had to be pumped in by some compressor or something to keep it pressurized. Is that not the case? The DIY at the top of this thread doesn't incorporate pressurizing.

No pressurisation required. The system pressurises as it heats up. It is a closed system by definition.

Niice..Ive been putting off doing a coolant flush because I thought Id need a pressurizing pump of some sort. Now its next on my to-do list once it gets a little warmer outside.

Thanks Glyn.

Not pressure, but vacuum…I use the W210-589-00-91-00 Radiator Lock Cap to pull 5-8” out of the system after a flush / fill…

Vacuum??? - what are you talking about - A vacuum would reduce the boiling point of the coolant. Pressure is required to increase the boiling point of the coolant !!!

Yeh Im pretty sure its supposed to be pressurized (not vacuum)...it says so right on coolant reservoir. But what Glyn makes sense in that after you put the coolant in, running the engine will automatically pressurize the entire system because its a closed loop.

Damn right it's a pressurised system. A vacuum can lead to cavitation & cavitation erosion which can be massively destructive and would cause boiling at a lower temp.

There is only a slight vacuum in the engine jacket water system when the engine is cooling down. This vacuum draws coolant from the radiator expansion tank.

This is maybe what BF JC is speaking of?

I am not suggestion cavitation, not at all (Or running a coolant system in vacuum under load)...quite the opposite actually, in that this tool is used to pull all air out of the closed loop (and rather complicated series of hoses) system, thus making it only coolant, no air. There is no vacuum placed in the system for use when the engine is on, only to extract the air after a full flush / refill. Once you extract all of the air, you remove the Cap and replace with the OEM Reservoir Cap

Mercedes-Benz WIS says to use Vacuum Cooling system filler, PN 285-589-00-21-00...

It is amazing to see how much air (bubbles) it will pull out of the system after a drain...You can then use the Cap with 124-589-24-21-00 or any other set up to pressure test the whole system...which of coarse is then, pressurized!

Sounds like a good system & safer for the engine. Airlocks can cause over heating damage.
I learn a lot from this forum!!

Excellent - now we understand one another - thanks BF - your initial post was a little cryptic

For DIY'ers - pulling a temporary vacuum to evacuate air is an elegant solution for dealers to ensure that the vehicle does not need a coolant top up a day after service but leaves the dealership with coolant at the correct level - but for DIY'ers that are reluctant to go to that expense there is nothing wrong with squeezing the hoses to avacuate major air. The rest will come out within 24 hours of running & you can do a final top off of coolant if necessary the next day - remember to do it when the system is cold.

um I didnt wanna make a new thread since its coolant related.. But I've been getting "CHECK COOLANT LEVEL" message on my dash for a few days now.. like when it was really cold it showed then again after a few days.. or sometime randomly after i start my car.. the coolant level seems to be normal.. i have an 05 c230 kompressor 6spd with 63k.. should i do a coolant flush.. wut coolant is good the Zerex G05 and where can i buy that ?

check your windshield wiper fluid. they're on the same circuit, so if your windshield wiper fluid is low, it will trigger the coolant level as well.

This isn't true for an 05 model. I'm not sure which year they fixed that stupidity on, but I know on my 05 the washer fluid warning is something to the effect of "Please add washer fluid", along with a washer fluid icon.

I have an '05 as well and when my windshield washer fluid is low, it says check coolant. I'm speaking from experience.

^^ hmm that could prolly be it.. i use my wiper fluid every minute haha.. cuz my blades kinda suck.. but i thought the coolant and washer fluid thing was on the older w203s no the 05 and up ones? anyone know

That's strange! You've got me, maybe that problem is specific to the C230?? Someone deserves to be fired for that design.
I can see myself pulling over during a sudden downpour to check my coolant because of that...

doesn't hurt to check and top-off your wiper fluid.

will do it tmrw ^ thanks.. oh whats the best place to order new oil filter for m271? we cant get the fleece anymore right?

You're right...No fleece!

...just get it at the dealer, it's not that expensive!

OK i topped of my windshield washer fluid and i still get the CHECK COOLANT LEVEL message on the dash when i start the car.. the temp is around 20 degrees.. where can i buy the coolant? is Zerex G05 the right one for my 05 c230 kompressor?

So i'm going to be performing this today or tomorrow.

I'm not sure where to find this "cap" on this step:
-What I did is flush the old stuff out with tap water...just open the cap and put the garden hose in there and wait for a few minutes.
-Wait for the tap water to drain out, then tight the plug back on.

Any one have a pic or can guide me where to find this cap?

I'm about to flush the system out since i have to replace my auxiliary pump tonight or tomorrow. Any suggestions or add-ons tips that any one wants to give me on top of what was posted on the step by step by the OP.

Thanks!

I used a similar process on my c55, except after running the hose for about 10 minutes, i closed up the drain, put the cap back on and ran the heater on full for about 5 minutes to circulate water thru the heater core. I then re-drained and did this a second time to give the heater core a good flush.

I also filled with G05 and distilled water rather than tap water.

Please be very careful doing this when hot as the cooling system IS pressurized and opening the radiator cap may cause steam to escape.

where do you get distilled water from?