TonyG230

Question on changing my antifreeze on my 02 C230. I have found the drain on the Rad. and the drain bolt on the engine block. My question is, the rad has no cap but the container beside the rad with the coolant cap does look like an overflow but I don't think it is. Will the coolant go out of it as I drain the rad and will the rad refill through it? The other question is how far do I fill it? Not sure if there shoud be some space for expansion?

MB-Dude

The container next to the radiator is probably is the overflow canister. Most MB overflow canisters dispense coolant from the bottom of the canister - look for about a 1" rubber hose running from the bottom of the canister to the base of the radiator. Also, if possible, take a sample of the fluid in the canister - if it looks like engine coolant, it probably is. To my knowledge, no other component uses a radiator cap, except the coolant circuit.

Changing the radiator coolant is fairly straightforward and it sounds like you've identified at least the radiator drain pet****. Personally, I would hesitate using the engine block drain plug... it may not be what you think it is. Instead, I would drain the system using the radiator pet****, and then disconnect the lower radiator hose at the radiator. This should drain virtually all the coolant. Reinstall the radiator hose (and while you're down there, check to make sure the hose is still in good condition). Whatever you do, save the environment and dispose of the coolant safely, as per your local regulations. During this, remove the radiator cap to allow air to displace the existing coolant.

At this point, I personally fill the engine coolant system with straight water (through the overflow canister), reinstall the radiator cap, and run the engine for a couple minutes – with the passenger cabin heater on HIGH. This step ensures at least fresh water has purged out any remaining coolant. Stop the engine and drain the radiator/engine as noted above.

Once the second purge is complete, refill the radiator with a proper mix of water and antifreeze, run the engine a mile (with the heater on HIGH) and recheck coolant level. You may need to readjust the coolant level once more, in a day or two as the last bit of air is released from the coolant system.

mercedestech2

Take the cap off of the reservior-the thing you see sitting to the side. Remove the bottom front belly pan. You'll see on the d/s of the radiator on the bottom a reb knob. Above this red knob you'll see a drain outlet. Attach a hose from this drain outlet to a suitable bucket of sorts. Open the knob, coolant will flow. When it's done flowing close the knob, remove the hose, reattach belly pan. Take bottle of coolant, fill reservior. Start vehicle, as reservior drains fill with water. Do this until car is at about 80C coolant temp as indicated by the cluster. When at 80 press the front defrost button on the ACC pushbuttons. No need to adjust temp as the defrost button defaults the temp to high. Rev the engine a bunch, even hold it at 3k and blip the throttle a few times until hot air comes out of defroster vents. Top off reservior and you are done.

TonyG230

Thanks for the info but still not sure about how much Anti freeze to put it. The reservour is not an overflow as the cap is a rad cap and designed to release under pressure so do I leave room at the top or fill to the top? AC on or heater on should do the same thing, wouldn't it? to fill up after start up. The block is also in question as I see a nipple same as Rad on the drain bolt and would like to drain to make sure "all" is out.

MB-Dude

The tank that has a radiator cap on it performs the function you think, but is not considered an "overflow tank" in the older, more traditional sense. The way the system works is that the radiator itself is completely filled with coolant and excess coolant is stored in the little tank. As the radiator coolant gets hot, it expands. As the liquid expands, it "expands" (or "overflows") into the little tank. When the engine cools, the coolant contracts, thus "drawing" coolant from the little tank. Any air in the engine cooling system is forced out as the coolant expands into the little tank. Hence the little tank is called an "Expansion Tank".

How much antifreeze to put in is completely dependent on the weather you expect. Being in Canada, you want more antifreeze than water. However, do not run 100% antifreeze. Not sure why, but it was always told to me that that's a no-no. Generally, a 50% antifreeze-50% water is a good place to start. Regular tap water will do just fine. For more details, the antifreeze container should have a little chart on it comparing freezing temperature to the antifreeze-water ratio. Follow the instructions on the container.

As for the amount of coolant mix to add, if you look inside the Expansion tank, you should see a little plastic tab or "wall" close to the side of the tank, under the radiator cap opening. This piece will be molded as part of the Expansion Tank and is the level gauge. When the coolant is not hot (un-expanded), the level should be close to the flat part of the level gauge. The gauge does not move, so do not look for anything movable. In fact, if you see something movable in there, something’s broken!

Also, your car will tell you if it's low on coolant fluid... the little yellow "Low Coolant" light will come on. If it does, simply add a little coolant mix.

TonyG230

Many thanks MB Dude. I have had the cap off to see the level when the engine was cold but didn't look for a level mark inside. I just noticed that it was about an inch below the top of the container and figured that the space was for expansion. Most cars give you a cold level and hot level and this is my first MB product. Don't like taking my car in for regular maintenance and will do the basics myself. Love the Forum for answers. The clutch fluid kind of has me but can see a rubber boot on the tranny case and think the bleeder is behind. The brake master looks like it does double duty and also is brake master of sorts. Not crazy about buying brake fluid from MB because their prices are triple from auto parts stores. Problem finding dot 4 that is good for 500 degrees. Valvoline is but it is Synthetic and don't think MB fluid is. Don't like mixing. I might have to bite the bullet and pay MB for brake fluid. Maybe I will find some Gold in the bottom of the tin, ha ha.