C63 W204 - Slight water leak

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Dunncb

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Location
Edinburgh
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C63 2 B
HI All, - 2014 C63 W204 26k - Slight water leak

Calling on experienced owners for advice.

After returning home from a 50 mile journey I noticed some wet spot patches where I drove into my drive way. I checked under the car and noticed there was water dripping from the rear of the engine bay.

I've put the car in the garage and placed a tray under the drip to identify if it continued. For the last four days it has been sat in the garage and dropping about 5ml of fluid per day. The fluid is clear and doesn't smell so I'm 99% sure its water. I have no warning indicators on the dash highlighting any issues.

I researched some online forums which mentioned it was possibly condensation from the air con system but I'm not so sure if it has been dripping for several days when the car is idle. I'm going to book it in to a MB specialist but I thought I would run it past you guys to see if you have had similar experience which may help settle my nerves?

I've attached some pics to identify the area in question but obviously the leak could be coming from anywhere above.

Many Thanks
 

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Hey buddy, there is a couple of things you can check.

a) check the black plastic feed on top of the thermostat. It connects to the overflow pipe which runs to the coolant reservoir. The coolant sometimes weeps out when the plastic gets brittle. You can see the tale tale sign of furring on the underside of the thermostat housing 20210830_183816.jpgas illustrated in the photo shown below. Unfortunately if its weeping, MB don't sell the plastic elbow, you have to purchase the whole thermostat unit.

b) also check the pet **** on the radiator or in general any cracks around the radiator. For that the bottom service panel needs to come out.
 
Might sound stupid but taste it you will soon find out if it's coolant
 
Hey buddy, there is a couple of things you can check.

a) check the black plastic feed on top of the thermostat. It connects to the overflow pipe which runs to the coolant reservoir. The coolant sometimes weeps out when the plastic gets brittle. You can see the tale tale sign of furring on the underside of the thermostat housing View attachment 118213as illustrated in the photo shown below. Unfortunately if its weeping, MB don't sell the plastic elbow, you have to purchase the whole thermostat unit.

b) also check the pet **** on the radiator or in general any cracks around the radiator. For that the bottom service panel needs to come out.
Thank you
 
If you have done the taste test to confirm it isn`t coolant or washer fluid then i would think that it is pretty safe to say it must be condensate from the A/C system as there is nothing else it could be.

K
 
If its clear with no taste it can really only be condensate from the air con. Get it on our cars, worries me every time I see it but then I soon realize what it is and relax. :cool:
 
If you have done the taste test to confirm it isn`t coolant or washer fluid then i would think that it is pretty safe to say it must be condensate from the A/C system as there is nothing else it could be.

K
Thanks. The water was clear and tasted pure enough with a slight essence of engine. I'll take a swig of coolant and have another taste of the water to compare, just to be sure. I'm sure I would have noticed first time tho.
 
If its clear with no taste it can really only be condensate from the air con. Get it on our cars, worries me every time I see it but then I soon realize what it is and relax. :cool:
Yea i hope so. I really like the sound of 'Relax'.
 
Thanks for all the advice. I'll give it another taste test and have a look at the seals around the coolant and radiator.

Lets hope it's just the A/C generating condensation. I'll keep an eye on it and maybe just get the garage to take a look when its in for MOT if it doesn't give me any more reason to be concerned.

Many thanks
 
Thanks for all the advice. I'll give it another taste test and have a look at the seals around the coolant and radiator.

Lets hope it's just the A/C generating condensation. I'll keep an eye on it and maybe just get the garage to take a look when its in for MOT if it doesn't give me any more reason to be concerned.

Many thanks
To be honest I think it’s air con , if you take a marker and with car level and at temperature put a we mark on water coolant bottle at the water level and check now and again if water level is going down should let you know if it’s losing water.
 
I can describe the antifreeze taste and it wouldn't be sweet 🤣🤣 you definitely wouldn't want to taste it again
 
I done that mate :)
I am experiencing a slight leak so to test it I dabbed a tissue in the liquid.No colour,
and when you apply a flame it does not ignite or smoke which to me suggests it’s water based and not steering fluid, oil or brake fluid.
 
I am experiencing a slight leak so to test it I dabbed a tissue in the liquid.No colour,
and when you apply a flame it does not ignite or smoke which to me suggests it’s water based and not steering fluid, oil or brake fluid.

Almost definitely air conditioning condensation - perfectly normal.
 

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