W202 coolant loss (c250td)

[mattc]

Noticed slight coolant loss under front drivers side of engine at the weekend. Have taken car to a friends garage this morning and they did a pressure check which yielded nothing and of course the underneath is dry as a bone. Any ideas/suggestions?

I monitor the fluid weekly as I do nearly 500 miles per week and I did need to top up the reservoir yesterday about 200ml.

As luck would have it I am going down to Olly's next Monday so they can look at it then however I am interested if anyone else has experienced elusive leaks like this?

Matt

 

[Dec]

Maybe you are over filling when topping up and its spitting out the excess through the open vent tube when the car is fully up to working tempature.

Dec

 

[mattc]

This weekend is the first time I have had to top it up so I don't think it's that in this instance.

 

[carat 3.6]

Possibly a leaking water pump.

 

[mattc]

The leak is in the right place for it to be the pump but why is it intermittent? Do I just monitor it and wait for it to get worse!? Is there a dye i can add to the coolant to make any leak more visible?

 

[Dec]

Check to see if coolant is leaking from the open pipe on the water pump.
The pipe that I’m talking about is discussed at the 8 minute mark in the video below.

https://www.youtube.com/watch?v=Qr2UwFBM90Y

Stuff some paper up into the pipe to see if it becomes wet after a drive.

Dec

 

[mattc]

Thanks for that suggestion. Will see if I can get to it tomorrow morning.

 

[HarioH]

Drivers side is 1/2" pipework for the heater equipment under the airbox, also atf cooler is in the driver side radiator header tank, as well as main engine rad hose on that side.

Can only suggest you check with a torch ideally after a hot shutdown (so theres most pressure in the coolant system to cause a leak).

 

[Silestanix]

Had an odd elusive water leak myself, turned out to be a faulty water pump as the little pipe underneath was wet.

Hope you find the cause soon anyway.

 

[HarioH]

Also the header tank overflow pipe is down in that area also IIRC?