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1998 S420
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My engine was running a little warmer than usual so thought I would flush and fill the coolant system. Was going to replace the thermostat but the lower real bolt on the housing is impossible to reach - must have to remove a bunch of stuff from the front of the motor. So not doing that now unfortunately by here's my problem. I drained my radiator and pulled the lower radiator hose to make sure I drained most of the coolant from the radiator. I filled the coolant reservoir and let the engine run until I thought the thermostat opened then put the cap on. Engine now overheats and aux fan runs once the temp builds. I loosen the cap on the coolant reservoir and allow it to empty itself. Putr the cap back on and run for about 3 minutes down the road and once again the temp heads toward 120. Shut it off and repeat the procedure. I am doing something wrong with filling the system. I seem to have created an air lock of some sort. Would appreciate any tips from anyone who can set me straight on the proper process to follow. Very grateful for any info!
 

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nothing broken. finally!
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WITH A COLD/COOL ENGINE:

1. drain radiator and coolant bottle
2. open bleed nipples on front of engine, 1 per side, drain coolant out of there.
3. change your thermostat. you may have to get the bottom bolt from below the car. here is where i tell people you cant do squat to these without a lift.
4. pre mix your mb coolant and water watter to your liking. 60/40 works good, 70/30 even better, where the 30 is destilled water, the rest coolant and the water wetter just on top
5. attach all your hoses and stuff back in and fill your water bottle.. some of it will immediately drain into the rest of the system but eventually stop.
6. crank the car and keep filling the coolant bottle until level settles about halfway in.
7. adjust as needed, check for leaks, check eng temp.
8. attach cap and test drive
 

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'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
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You ask the "correct" method? Here's what you need to do it the WIS specified way:

Make your life easy, crack open your wallet and get this device for $69 bucks. You can suck out every drop of air in the system, and re-fill with NO bubbles.You can also check for leaks at the same time..

Cooling System Vacuum Purge Tool,Mercedes,BMW,VW,Honda: eBay Motors (item 370452769858 end time Dec-02-10 21:02:27 PST)

And the procedure:

http://www.benzworld.org/forums/w140-s-class/1444114-photo-diy-coolant-service-la-vacuum.html
 

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'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
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Did you measure what amount of fluid you drained and put the same volume back in?
Yes. But its not an exact science, by any means. Place a few 100 cc's "extra" in your "fill" bucket.
 

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current fleet: 1996 s500; 1997 BMW 328ic; 2000 Nissan Frontier; 1966 AC Cobra
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WITH A COLD/COOL ENGINE:

4. pre mix your mb coolant and water watter to your liking. 60/40 works good, 70/30 even better, where the 30 is destilled water, the rest coolant and the water wetter just on top


Sorry Gyrate -you are slightly misguided here. The heat transfer rate of water is better than that of antifreeze. Thus, the cooling capability of your car is increased with a minimum amount of antifreeze in the mix. Rarely is a mix greater than 50/50 recommended unless you are in a very severe climate, which you may be. So, lower your antifreeze ratio to maximize your cooling capability.

"Water Wetter" is a product that reduces the surface tension of water, thus further increasing the heat transfer abilities. Water Wetter also has lubricants that are helpful to your cooling system.

You should use the minimum amount of antifreeze for your climate. Antifreeze also raises the boiling point (which is needed) but must also work in tandem with your radiator cap maintaining appropriate pressure in the system

As a general rule - more antifreeze is not "better" from a perspective of cooling capacity

Hope this helps
 

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'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
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The 50/50 mix is a good compramise of heat dispersion, and corrosion protection.

Water Wetter? I've tried a few different types over the years, and haven't been terribly impressed with the difference ("if" any!).
 
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