The 560SEL has developed an intermittent coolant leak that appears to be coming from somewhere near the catalytic converter (approx 24" back from the front axle and inboard approx 12" near the front passenger side of the car). I'm thinking of purchasing a UV leak detector kit to track down this problem and fix it.

This kit looks interesting; however I'm open to any suggestions.

http://www.amazon.com/Mastercool-53351-B-Professional-Detector-Light/dp/B000IHJXHG/ref=sr_1_fkmr0_1?ie=UTF8&qid=1459213396&sr=8-1-fkmr0&keywords=masterpro+leak+detector+kit

Possibly a hose going somewhere to the heater core or possibly the heater core has a small leak. Not 100% sure, but that seems like the only logical explanation given the location of the leak.

__________________

1990 190E 3.0L

Check freez plugs for corrossion .

...not sure about the S-class, but my 201 has a heater coolant valve under the cowl in about the same location that you are descibing. I think it's normally closed and has a vacuum diaphragm to open it when heat is called for by the Tempmatic system. There was a slight coolant leak coming down on the transmission from the heater box drain. After removing the plastic cowl screen to access the area I could clearly see that the valve was seeping, and it was easy to swap in a new one.

Duke

Thank you for the advice; I'm going to remove the cowl screen to see what can be seen. I"ll report back with updates.