Coolant drip from drivers side radiator area ML550
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Junior Member
Joined: Jul 2020
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2011 C300 (2)2010 ML550's 1978 280CE Coupe 32k
Coolant drip from drivers side radiator area ML550
Hello, I have a steady drip of coolant coming from drivers side of my 2010 ml550, at first I thought it was coming from the large hose so I ordered a new one. However got my hand down all around the large hose neck and its not wet at all, it right below that where the fluid starts. I cant tell if its that smaller diameter hose with a brass fitting (because that is all wet for sure) or its coming from the radiator seam itself? I keep drying it all and using flashlight and mirrors but still hard to tell. I started thinking maybe its just the smaller hose fitting leaking, but do you all know if its more likely the radiator in that spot? Its right below the large hose and could be the smaller hose connection or the radiator plastic, just to hard to pinpoint.
Senior Member
Joined: Oct 2023
Posts: 473
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From: New Hampshire
ML 63 AMG
Hello, I have a steady drip of coolant coming from drivers side of my 2010 ml550, at first I thought it was coming from the large hose so I ordered a new one. However got my hand down all around the large hose neck and its not wet at all, it right below that where the fluid starts. I cant tell if its that smaller diameter hose with a brass fitting (because that is all wet for sure) or its coming from the radiator seam itself? I keep drying it all and using flashlight and mirrors but still hard to tell. I started thinking maybe its just the smaller hose fitting leaking, but do you all know if its more likely the radiator in that spot? Its right below the large hose and could be the smaller hose connection or the radiator plastic, just to hard to pinpoint.
Thread Starter
Junior Member
Joined: Jul 2020
Posts: 73
Likes: 7
2011 C300 (2)2010 ML550's 1978 280CE Coupe 32k
Thank you, it really seems to be that smaller diameter hose (I can almost see an o-ring but my eyes may be playing tricks) below the large main hose but again super hard to see for sure, and could be radiator right there between the small hose and the upper large hose. Wondering if techs genarally see that exact spot as the radiator and not the smaller hose or o ring.
Senior Member
Joined: Oct 2023
Posts: 473
Likes: 241
From: New Hampshire
ML 63 AMG
Thank you, it really seems to be that smaller diameter hose (I can almost see an o-ring but my eyes may be playing tricks) below the large main hose but again super hard to see for sure, and could be radiator right there between the small hose and the upper large hose. Wondering if techs genarally see that exact spot as the radiator and not the smaller hose or o ring.
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Joined: Jun 2014
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
There are a few spots to look for the leak. The W164s are known for having the tanks on the side of the radiators, crack. I understand that its more prevalent on the V6 models than the V8. Under the radiator on the engine side are two hoses. One goes from the engine block to to radiator with a union midway that then flows along the bottom of the radiator and up to the secondary electric water pump for the heater. In addition, there is the expansion tank hose that connects at the ttopof the radiator s well as the traditional top radiator hose. There is also to the red drain plug at the bottom. The document attached might give you some more guidance. Any decent shop can pressure test your cooling system as has been noted and find the leak quite quickly.
Last edited by BlackML550; Feb 4, 2024 at 04:51 AM.
Thread Starter
Junior Member
Joined: Jul 2020
Posts: 73
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2011 C300 (2)2010 ML550's 1978 280CE Coupe 32k
Thank you so much to all of you! I will get pressure test next and see, it either that smaller hose on drivers side right below the large hose or the radiator seam right in that same spot.
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Thread Starter
Junior Member
Joined: Jul 2020
Posts: 73
Likes: 7
2011 C300 (2)2010 ML550's 1978 280CE Coupe 32k
It was a pinhole leak just below the upper radiator hose where there is a seam, it kept increasing in the amount of coolant it was losing. Had a new Nissens radiator installed and all good now.
