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I drive a 2010 c250 cgi and I've just found a coolant leak on this image below. But cannot figure out the name? Is it the water cooler valve? It's a minor small leak and could be a rubber seal inside which is gone but would like to know name and rough price of this part. Thanks for any help in advance. Wondering what the name of this part circle in blue. The red circle is where the leak is originating. This part is right next to the power steering reservoir.
I dont have that engine but was looking around to see how that joint is sealed, looks like there is an o-ring inside the valve. Wonder if that o-ring is worn and is what is making it leak. May be able to find a replacement, though nothing is shown in the parts diagram to order one. The plastic pipe doesnt look like there is any type of o-ring/seal on it.
I would try disconecting that pipe and inspect the o-ring. May be able to get away with cleaning it and putting it back together. Maybe the connection just backed away a little, reseating it may fix the leak. One of my floor jacks was leaking jack oil from the plunger, I took it apart and was going to install a new o-ring I bought but it was the wrong size, so put everything back together and now its not even leaking, maybe reseating everything fixed it, at least for now.
Can see the o-ring in green in a photo of the valve I found online:
Hi alynch. Thanks for identifying the part. Quite a few names for it so was bit difficult.
Hi Tim. Thanks for the detailed response. Would any generic O ring fit, assuming it is the O ring? Or would it need to be a heat resistant one? First time I'll be working on my own car so I appreciate any response provided.
I appreciate the response Tim. Will keep you posted with the result. Had another look today at the valve and it was dry. Was wet with coolant yesterday. Maybe because I hadn't driven it since.
This valve is part of the circuit that feeds the heater core. My valve was leaking and had failed, so there was no heat inside the vehicle. Since you have to remove the valve to inspect the O-ring and the valve is 14 years old, I would just replace it.
Might be best to change the valve. Had no heat for a day or two on the driver side back in winter the one time. Been fine since. Probably just needs to be changed completely. Thanks alynch
Hi guys, just an update. Managed to change the part. The old part looked fine including the o rings. Bit of coolant loss from the job but part has been replaced.
There was some excess residue straight after the job but stayed dry for a day. I've gone to check today and it feels wet again from the same part circled in red on the picture above and I saw a droplet mark. Any advice would be greatly appreciated.
Would any excess coolant still drip out for a few days?
Hi guys, just an update. Managed to change the part. The old part looked fine including the o rings. Bit of coolant loss from the job but part has been replaced.
There was some excess residue straight after the job but stayed dry for a day. I've gone to check today and it feels wet again from the same part circled in red on the picture above and I saw a droplet mark. Any advice would be greatly appreciated.
Would any excess coolant still drip out for a few days?
Dry off and clean the area around the part you replaced. Look for hairline cracks in the plastic pipes, especially the seams (second picture in TimC300's post #3). Check with the engine running and full heat inside the car. The coolant system is pressurized when the engine is running and leaks are easier to locate. Sprinkle a little baking soda or baby powder under the parts you suspect are leaking and the coolant will cause the powder to clump.
Which brand part did you buy, Mercedes or aftermarket?
I was going to say inspect the pipe for cracking. You just replaced the part with the o-ring so it should be fitting snug in there.
I would wipe/dry that connection really well with paper towels. Then start the car and check the connection for coolant coming out. Use a paper towel to see if it wicks up any coolant.
Hi everyone. Did everything mentioned above. Seems to be dry now. Coolant level dropped slightly from some spills when replacing the part but seems to be sitting level now.
On a side note, I had a look at the coolant resovoir today with the engine running at 90 degrees and saw some bubbles forming at the top of the coolant. Is this something to worry about? I know these systems are self bleeding but wondering if there are air pockets in the system from the fix and if I need to bleed it myself?
When I replaced/re-filled the coolant I did not do anything special. I filled the coolant reservoir, started the engine then kept adding coolant as the level went down until it seemed to be staying the same. I topped it off the following day or two since it did go down just a little. This was when I replaced the oil filter housing gaskets in my M272 engine. Instead of draining the coolant from the bottom of the radiator I just pulled the oil filter housing and let the coolant gush out, which turned out to be alot. Took over 6 liters to fill it.
Not sure about your 250 but our M272 was indeed self-bleeding. Drained the radiator and drained the reservoir for the OFHG R&R. Filled it to the middle mark then started and the level came down. Drove around to open the thermostat and the level went down again. Topped it off, checked again in a week but I was good.
I personally would only add 50/50 pre-mixed coolant to top it off, the winters get cold around here so I want to make sure I have the correct amount of antifreeze in the system. Would you be fine just adding a little bit of water to top it off, probably.
I use Zerex 50/50 pre-mix. I can find it on sale locally for around $13 a jug.
You should be fine checking the coolant level the next day or two and topping off if needed. You shouldn't have to do anything special.
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