Coolant Flush for W205?
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Joined: Oct 2025
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C250d
Coolant Flush for W205?
Hi All, Just wondering if anyone here has done a coolant flush on a C-Class W205? I've done some research but haven't found much detailed information on the process.
From what I've seen, the official Mercedes procedure appears to require a special vacuum machine for refilling the coolant system. Is there a safe and effective DIY method without that equipment?
My car is a 2016 C250d (OM651 engine) which has two separate coolant reservoirs. I've noticed that the radiator itself doesn't have a filler cap, so the only access point for refilling seems to be through the expansion tank. That's fine — I've seen other vehicles designed that way — but I can't find any obvious outlet for air to escape. Am I correct in assuming the expansion tank is already the highest point in the system, or is it specifically designed to be vacuum-filled to avoid air pockets?
Lastly, I have a Foxwell NT530 scanner. Does anyone know if it supports bi-directional control of the electric water pump for performing a coolant flush or bleed procedure?
Thanks in advance for any advice or experiences you can share!
From what I've seen, the official Mercedes procedure appears to require a special vacuum machine for refilling the coolant system. Is there a safe and effective DIY method without that equipment?
My car is a 2016 C250d (OM651 engine) which has two separate coolant reservoirs. I've noticed that the radiator itself doesn't have a filler cap, so the only access point for refilling seems to be through the expansion tank. That's fine — I've seen other vehicles designed that way — but I can't find any obvious outlet for air to escape. Am I correct in assuming the expansion tank is already the highest point in the system, or is it specifically designed to be vacuum-filled to avoid air pockets?
Lastly, I have a Foxwell NT530 scanner. Does anyone know if it supports bi-directional control of the electric water pump for performing a coolant flush or bleed procedure?
Thanks in advance for any advice or experiences you can share!
MBWorld Fanatic!
Joined: May 2018
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W205 2015
Hello I have 2 coolant reservoirs I don't recommend diy it looks there is vacuum to be used + bleeding for these 2 reservoirs. So I went to the dealer 5 liters of oem coolant + manpower service all together 110 usd. They mixed the 5 liters of coolant with 5 liters of distilled water.
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2018 C300 (w205, m274, 725) and 1995 Ford Bronco (5.8 Windsor)
Coolant Flush
Former Benz tech here. The way we always did coolant flushes as far as the fill/bleed goes, Theres no electronic bleed procedure. We use a tool like whats linked below. Drain off all the coolant, use this to pull vacuum, (should be roughly 23-26 psi), let it keep pulling vacuum for like 2-3 minutes, close off all the valves and make sure it holds vacuum before filling. I always waited like 3 minutes at least to make sure it holds. from there, you use the fill hose that comes with the kit. stick the hose into the coolant jug (MAKE SURE NO AIR GOES THROUGH THE SYSTEM but the little bit thats already in the hose before using it doesnt matter), and then open the valve that the hose is attached to. The vacuum pulls the coolant through the whole system. Newer models have an electronic bleed procedure, but not our 205 chasses.
https://www.fcpeuro.com/products/coo...t=All%20Others
https://www.fcpeuro.com/products/coo...t=All%20Others
MBWorld Fanatic!
Joined: May 2018
Posts: 1,246
Likes: 243
W205 2015
Former Benz tech here. The way we always did coolant flushes as far as the fill/bleed goes, Theres no electronic bleed procedure. We use a tool like whats linked below. Drain off all the coolant, use this to pull vacuum, (should be roughly 23-26 psi), let it keep pulling vacuum for like 2-3 minutes, close off all the valves and make sure it holds vacuum before filling. I always waited like 3 minutes at least to make sure it holds. from there, you use the fill hose that comes with the kit. stick the hose into the coolant jug (MAKE SURE NO AIR GOES THROUGH THE SYSTEM but the little bit thats already in the hose before using it doesnt matter), and then open the valve that the hose is attached to. The vacuum pulls the coolant through the whole system. Newer models have an electronic bleed procedure, but not our 205 chasses.
https://www.fcpeuro.com/products/coo...t=All%20Others
https://www.fcpeuro.com/products/coo...t=All%20Others
