I've read some stuff, watched a video on cleaning the W210 heater control valve (the duovalve). My 99 E300 has 154k miles on it. According to the PO, several years ago he took it apart, cleaned it, and it's been fine since. Over my couple of months of ownership, it's acted up a few times (heat out the left vent) but whacking it a few times has helped.

Those of you who've been down this road....does cleaning tend to buy you a few years and can you just go on doing this indefinitely? Or, when it starts to clog like this, is it nearing the end of it's usable life and requiring more frequent attention?

I don't want to be constantly hassling with it....I'd sooner just buy a new one, but of course they're pretty pricey.

Thanks.

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 178k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 75k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife