Yidney

I'm having trouble finding a detailed coolant flush procedure the way it would be done if you were not taking shortcuts or mixing old with new. I know about the drain at the bottom of the radiator, but what about the block and heater core? I understand there is a drain of some sort in the block. Where is it located on a M273? Any risk loosening that - such as "they usually break off" or anything? We have very detail tranny fluid instructions on the forum. I'm surprised I cannot find a similar coolant one.

Plutoe

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irokdastar

I think the best method without having to look for plugs and try to open something that you might thread or have other issues with . Just got and buy 4 gallon of distilled water its like a $1 each at Walgreens . drain the radiator and fill with the distilled water . Run the car for 15 minutes making sure you have enough water in the system . once you get to operating temperature run the heat inside the car so it can go through the heater core . Then drain and keep doing this till you get clear water in the system . then drain the radiator and measure how much water it holds then fill it up with coolant . I think total system takes 3 gallons . Please check this I am not sure . now add the same amount of coolant as measured coming out of the radiator . make sure you use regular coolant not 50 /50 mix . warm the car up again and check the level and your done .

Yidney

This makes sense. I think Rodney said the system is self bleeding, so you don't need to do all the stuff you need to do on Audis, etc. Of, course, you do the final level check when it's all cold. How many times did you flush it? What did you do with all that waste coolant? I think I read the system holds like 9.7 quarts, so 2 and a half gallons. So as long as you can fit 1 and a quarter gallons in the radiator on the last fill, that should be a 50/50 mix.

irokdastar

I did this on my bmw. for the waste coolant I took it to AutoZone they recycle it for free. . I had to do this about 2 times but again it depends how dirty your coolant is . If you cant make it 50/50 due to the radiator not holding enough coolant . don't forget the reservoir you can add coolant only there to make up for it . Also you are you ok if its not 100% 50/50 . If you add more water your freeze point goes up . SO as long as your in the ballpark you should be fine.

Rutland75

At what mileage should the coolant be replaced?

irokdastar

It depends on the color really . If it looks clean then its fine . You can go to autozone and buy test strips so you can see how good or bad the coolant is .

Rudeney

The system is self-bleeding. I've never worried about draining the heater core and block - I've found that draining from the radiator get about 85% of the old coolant out.

degeja

Mercedes service manual says 140,000 miles or 15 yrs.

Yidney

I'm not doing it because it's old. I'm doing it because I'm replacing my water pump and I'm not going to put old fluid back in.