603 block coolant drain
 

My coolant is getting low, and its probably pretty old, so I would like to drain out every drop of coolant and refill with new. Where is the drain on the motor? And how much does the entire system hold, engine and radiator and overfill tank?

Thanks much

Oh, and i *think* it has the green stuff in there now, should I switch to the MB orange stuff?

turbodiesel I didn't realize the orange stuff was MB. how long do you think it's good for?

First, Isn't there a plug on the block to allow complete drainage?

Second, to rekindle the antifreeze debat... The orange uses chemical that capture any calcium or magnesium in the water mixed with it. The green stuff makes small white crystals which can be seen in the radiator in stead. If these crystals accumulate it blocks the fine passageways of the MB radiators. The orange is supposed to be 100,000 mile stuff too.

One can always be safe and stay with the MB coolant.

Yeah, im trying to find out exactly where the drain is on the block.

ALso, if I do convert to the MB stuff, do I have to completely flush my system of all the green stuff? Like run a garden hose thru and make sure every drop is out?

turbodiesel,

The block drain is usually on the passenger side of the block, near the center (looking from front to back) or a little forward of center. I believe it is a 19 mm hex head bolt just screwed into a small boss on the block. On a 240D it is right next to the bracket that supports the front of the starter. It is in a similar spot on my 190E 2.3-16 although the starter is in another location.

If you are going to drain the block, you should use the garden hose method to rinse the old stuff out, and you should open the drain at the bottom of the radiator to get the most solid stuff out the shortest path. I would also recommend getting the MB citric acid powder to flush the system, which means another drain and flush cycle. I use the MB antifreeze exclusively, and it is clear, not orange (and has been clear for ten or more years now). I do add Redline water wetter, which makes the whole concoction pink, but also helps identify coolant leaks if you get them (a more apparent pinkish residue builds up at the leak). Good luck and I hope this helps, Jim

Thanks Jim,

How would I go about flushing the block? Take the thermostat out and put the garden hose there and let it run thru? And how about the radiator? I've never done this before..

turbodiesel,

I am not sure about the exact configuration of your radiator, but the 240D has a small plastic threaded plug on the bottom on the driver's side. When you unscrew it, the plug drops down an inch or so but has a lanyard to hold in the hole (it does not come off in your hand). I imagine this is similar on your car. When you open this drain plug, most of the coolant will come out (take the cap off the expansion tank too and set the heat controls to full heat on - with the car running in your case as this is all done by actuators that do not respond when car is off - the 240D has a mechanical actuator connected to the temperature selector knobs in the car). The 240 has no expansion tank, the cap to fill the system is right on the radiator so you just run the garden hose in the top of the radiator.

If you run water in the expansion tank the fill line to the system should carry it into the block and the radiator should fill up without taking the thermostat off. I reinsert the radiator plug, let the system fill, drain it out, repeat until it looks clean and feels clean. With antifreeze in there it ususally feels a little slippery.

Then I do the same thing except with the block plug. Once the system is pretty clear, I run the car to normal operating temp with just water in it and drain it out again. When I use the citric acid stuff, I add that at this point when I refill the system, run the car for a good half hour at temp, and drain and flush a few more times. Then I refill the system with the antifreeze and water wetter. I usually try to do this with the car nose aimed uphill (I have a small hill in my yard) so the air will not get stuck in the head, or the heater circuit as I am filling it. Hope this helps, Jim

Jim:

I just got a bottle of the citric acid from MB (see my other thread), I also read that it should be used to make a 10% solution, meaning I would, in theory, need 2 bottles.


Do you get 2 bottles, or jsut one, when you flush your system?

Capt Kirk,

When I got my citric acid it was a largish jar of powder with no instructions. I asked the parts guy at the dealer how you use it, and he did not know but asked one of the guys in the shop. He said to just dump it in the radiator/coolant fill opening, and fill the system with water, then let it run at temp for about half an hour. That is what I did and it seemed to work. Jim

Thats the same advice I got. But I was looking at the CD and it said to make a 10% solution and run that. Hearing that one bottle worked for you is reassuring because I'm flushing the system tomorrow, and I don't have a 2nd bottle :D