Windshield washer reservoir - rank smell

First thought was the air intake filter for the ventilation system - filter was clean and it did not carry the smell.
The windshield washer reservoir sits directly underneath the air intake/filter body - when I popped the cap off and took a whiff I knew I had found the problem.
Carefully removed the tubing to the first nozzle in the hood and used the windshield washer pump to evacuate the reservoir into a bucket. If you need deer repellent, this stuff would probably have worked.
Poured in some distilled water to flush and pumped again. All better now; next trip to MBZ I'll probably get some of their concentrated goo for the reservoir.
I have a 2003 E500 and I think I may be experiencing the same thing that you did. I popped the cap off the windshield fluid reservoir but didn't smell anything. Does the vehicle have to be running when you do this or does it not matter at all? It really smells when I turn on the A/C or heater!!!

1. There is a service note that dealers have addressing some sort of a chemical flush of the air system - possibly addressing mold.
2. Also, different years had filter(s) that should at least be inspected - some had separate particulate and activated charcoal filters.



