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Hi all,
Did a few search and did not find exact information I wanted. I discover a pin side leak in the coolant reservoir. Coolant kept draining for a few weeks, had Mercedes dealer check during annual service and pointed it out to them. But I was not told anything about it or to worry after they clean it. They did do the steering because of the recall. After they cleaned it, I check every day but can not find any leak under the car. I did a pressure test and it also did not discover any problem and held onto the pressure just fine. It will leak halfway and then stop. I will get the check coolant level message but the level at the halfway point will stay the same. I suspected the cap or maybe the tank itself around the top was leaking after searching on the forum. Last night I filled up the coolant and drove it around the neighborhood and finally saw some smoke and was able to check and find the leak.
I can replace the reservoir. However, I want to do it correct. I am a bit worry that the pressure test didn't show anything. Beside the tank, should I go ahead and replace the cap and lines as well? There were always a bit of residue on the cap so I think the cap itself is not giving a proper seal.
Also in my search I am reading about headbolt. It got me a bit worry but I am not having any of the issue describe. What I had experience are the collision sensor becoming more sensitive, especially the right side. It is going off in my driveway or garage, I am thinking maybe some coolant got in and touch some electrical. I had not had time to look but if anyone can chime in. My questions are:
Headbolt - I don't think it is something I should worry about, but would like other thoughts.
Should I be concern that the pressure test did not find an issue?
Given that I read this is a common issue, would replacing the tank be enough or I should be extra careful and get the kit from fcp? Anything else I should check for?
Do I need to worry about the coolant line and change those too? Like I said, I rather do this right the first time.
Finally are there any other sensors in the area that could be affected. Ever since I had my car service, my front end, both tires have been loosing air overnight and have the slam look but rise when I start every morning. I never had this issue until I got the steering bolt recall work at the dealer and now, not sure if they connected everything properly.
Hi all,
Did a few search and did not find exact information I wanted. I discover a pin side leak in the coolant reservoir. Coolant kept draining for a few weeks, had Mercedes dealer check during annual service and pointed it out to them. But I was not told anything about it or to worry after they clean it. They did do the steering because of the recall. After they cleaned it, I check every day but can not find any leak under the car. I did a pressure test and it also did not discover any problem and held onto the pressure just fine. It will leak halfway and then stop. I will get the check coolant level message but the level at the halfway point will stay the same. I suspected the cap or maybe the tank itself around the top was leaking after searching on the forum. Last night I filled up the coolant and drove it around the neighborhood and finally saw some smoke and was able to check and find the leak.
I can replace the reservoir. However, I want to do it correct. I am a bit worry that the pressure test didn't show anything. Beside the tank, should I go ahead and replace the cap and lines as well? There were always a bit of residue on the cap so I think the cap itself is not giving a proper seal.
Also in my search I am reading about headbolt. It got me a bit worry but I am not having any of the issue describe. What I had experience are the collision sensor becoming more sensitive, especially the right side. It is going off in my driveway or garage, I am thinking maybe some coolant got in and touch some electrical. I had not had time to look but if anyone can chime in. My questions are:
Headbolt - I don't think it is something I should worry about, but would like other thoughts.
Should I be concern that the pressure test did not find an issue?
Given that I read this is a common issue, would replacing the tank be enough or I should be extra careful and get the kit from fcp? Anything else I should check for?
Do I need to worry about the coolant line and change those too? Like I said, I rather do this right the first time.
Finally are there any other sensors in the area that could be affected. Ever since I had my car service, my front end, both tires have been loosing air overnight and have the slam look but rise when I start every morning. I never had this issue until I got the steering bolt recall work at the dealer and now, not sure if they connected everything properly.
I'm currently having the same issue and I was looking at replacing the hose because it seems to be leaking which is causing my coolant to go low. I'm looking for the hose would anyone know the part number?
I'm currently having the same issue and I was looking at replacing the hose because it seems to be leaking which is causing my coolant to go low. I'm looking for the hose would anyone know the part number?
It's the same Hose that is in the picture and in the video leak for this thread. I mean it's doing exactly the same thing. it looks like a fine pin whole leaking coolant out of the hose dripping on the engine. the dealership told me it was a oil leak cause smoke but you can clearly see the coolant dripping from the hose. VIN# WDDKJ7DB9EF243343
No, each part is separate. I made a mistake thinking it was the hose between the reservoir and radiator, when you mentioned hose. What do suspect is leaking?
If its the coolant hose in the photo above, I can't say for sure since I don't have a M278. A wider angle photo would help with where the hose connects on either end. I'm thinking it runs back to the heater core.
To me the video shows a leak from the reservoir, maybe a tiny split in the seam between the upper (black) and lower (opaque) halves.
Here you go:
so this is line that I mention before. Just like the leak video in this thread. Its leaking coolant right from this line not sure what it's called as far as the part.
That line goes to the pre-fuse box, positive jump point circled in yellow, right? That’s your battery positive cable, so it can’t be leaking coolant. Unless the corrugated sleeve is filling with coolant from somewhere else and leaking out where your pointing to.
Take a better look... make sure coolant reservoir is filled to correct height, warm up engine, while engine is running open hood and check for leaks in the area.
Hi all,
Did a few search and did not find exact information I wanted. I discover a pin side leak in the coolant reservoir. Coolant kept draining for a few weeks, had Mercedes dealer check during annual service and pointed it out to them. But I was not told anything about it or to worry after they clean it. They did do the steering because of the recall. After they cleaned it, I check every day but can not find any leak under the car. I did a pressure test and it also did not discover any problem and held onto the pressure just fine. It will leak halfway and then stop. I will get the check coolant level message but the level at the halfway point will stay the same. I suspected the cap or maybe the tank itself around the top was leaking after searching on the forum. Last night I filled up the coolant and drove it around the neighborhood and finally saw some smoke and was able to check and find the leak.
I can replace the reservoir. However, I want to do it correct. I am a bit worry that the pressure test didn't show anything. Beside the tank, should I go ahead and replace the cap and lines as well? There were always a bit of residue on the cap so I think the cap itself is not giving a proper seal.
Also in my search I am reading about headbolt. It got me a bit worry but I am not having any of the issue describe. What I had experience are the collision sensor becoming more sensitive, especially the right side. It is going off in my driveway or garage, I am thinking maybe some coolant got in and touch some electrical. I had not had time to look but if anyone can chime in. My questions are:
Headbolt - I don't think it is something I should worry about, but would like other thoughts.
Should I be concern that the pressure test did not find an issue?
Given that I read this is a common issue, would replacing the tank be enough or I should be extra careful and get the kit from fcp? Anything else I should check for?
Do I need to worry about the coolant line and change those too? Like I said, I rather do this right the first time.
Finally are there any other sensors in the area that could be affected. Ever since I had my car service, my front end, both tires have been loosing air overnight and have the slam look but rise when I start every morning. I never had this issue until I got the steering bolt recall work at the dealer and now, not sure if they connected everything properly.
Based on your pictures you definitely have a reservoir leak and MB pressure test not showing this is a bit of a mystery. The test is with 17 psi to see if the system holds pressure. I don't know how long they test. I just happened to do the test myself and my system held 17 psi for two hours so I think it is ok but perhaps the pressure in the system is higher during engine fully warmed up? Or is that 17 psi just below the pressure the reservoir cap springs relieves the pressure?
Anyway, if you see some residual in the cap it means the reservoir filled up all the way with hot engine and the relief valve on the cap let some coolant out. This is proper function for over filled cooling system.
17 psi test pressure is not enough, at least for my pressure cap which stated 1.4 BAR ( 20.58 psi ) and WIS stated so too. I am sure all this type of coolant reservoir has the same pressure cap rating of 1.4 BAR for W212.
Does your radiator system tester has the adapter to also test the plastic pressure cap too ?
I am having tough time buying locally a tester specific to current W212 MB style cap.
I think we need to test to 21 - 21.5 psi till the pressure cap spring releases at a bit above 20.58 psi, at least we the know the cap is healthy and the radiator system overall can handle +-21 psi.
17 psi test pressure is not enough, at least for my pressure cap which stated 1.4 BAR ( 20.58 psi ) and WIS stated so too. I am sure all this type of coolant reservoir has the same pressure cap rating of 1.4 BAR for W212.
Does your radiator system tester has the adapter to also test the plastic pressure cap too ?
I am having tough time buying locally a tester specific to current W212 MB style cap.
I think we need to test to 21 - 21.5 psi till the pressure cap spring releases at a bit above 20.58 psi, at least we the know the cap is healthy and the radiator system overall can handle +-21 psi.
I did 17 psi because a MB SA said that is what they use for the test pressure.
I don't know if I have adaptor for the cap. I bought the test kit from Harbor freight. It has all sorts of adapters for different cars but doesn't really have one for MB. Have to use adjustable bracket with a plug on the tank. It worked but took awhile to figure out how to set it up. I have not looked at testing the cap yet.
