clb0099

Hello all,

Over the last couple of months I was experiencing a mystery coolant leak. At first my mechanic discovered that my reservoir was leaking so he replaced it with an oem one. At the same time I decided to have him do the water pump, thermostat, all the pulleys, and finally harmonic balancer. Figuring that the coolant leak was fixed I didn’t think the coolant refill warning would come up again.. well I was wrong it did.. it went back to the mechanic to have that coolant light checked as well as the front/rear rotors and pads replaced. It was this point where another coolant leak was discovered. The part leaking was the Water Hose - Feed Hose from Engine to Auxiliary Water Pump. I was sure that after this was replaced that this would definitely fix the issue of coolant light. Well it didn’t.. the light is back again! When I opened up the coolant reservoir it coolant level was fine. There is no air in the system from what I can tell cause my mechanic is did exactly the dealership does it as he use work the local Mercedes dealership as mechanic prior to opening his own shop. What I did notice is that when I run the heat in the car the coolant refill light shuts off. As soon I turn off the heat the light goes right back on. I am at loss as to what to do next.

The Thomas J

This tends to happen as you replace old parts with new ones. The older parts up the line give out. It's most likely another leaking hose. You have to get in there with a flashlight while the engine is running and poke around.

clb0099

The problem is that the coolant tank is full … there isn’t any leak anymore and still the light comes on. I was even thinking that the heating element inside the windshield reservoir might be an issue. I am totally at a lose.

Senecat

Your mechanic is an official Mercedes tech with his own shop. What are you doing here?

clb0099

cause even the best get stumped sometimes.. he said that I should see if others had this same issue after replacing parts. But thank you for your input.

Arrie

How about the level sensor in the reservoir?

clb0099

The level sensor and reservoir is all one piece.

Senecat

Bad harness connection?

clb0099

So here is something that I am not even sure has any relevance. The windshield reservoir was empty and I rescanned the car with my Mercedes icarsoft and got 2 errors. One of them was for the windshield reservoir and the other was for the low coolant light. I had a slow leak coming from the windshield reservoir that I just fixed as it was one of the rubber gaskets that have become old and cracked. Once I replaced that gasket I filled up the windshield reservoir and the coolant low refill message went away I am not sure if they are related but thankfully the light is gone for now.

vettebk

Clear the code and see if it returns. If you don't see anything leaking, it has to be a sensor. I suppose you could have a bad sensor inside a new coolant recovery tank, but that seems odd.

clb0099

So as of now it’s all good.. I cleared them after I filled up the windshield reservoir.. let’s see if it holds up

The Thomas J

That's very strange. My Windshield washer tank leaks and I have never had a low coolant light in connection with a low washer fluid message.

clb0099

Mine was completely empty not low.

Arrie

So, for the interest of perhaps more than just me would you be willing just to employ your windshield washer tank and see if the low coolant warning comes back?

It just does not make any sense this being somehow connected to engine coolant level.