Last year I replaced the bottle, the pump washers, and one pump. I never even noticed the valve when I did those tasks.

There are no leaks, but the blue juice sure was steamy!
I pulled the coil and flushed it - completely clean fluid and no debris came out.

I'll be ordering a new thermovalve shortly.

Thanks everybody
Fred

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Thank You!
Fred
2009 ML350
2004 SL600
2004 SL500
1996 SL600
2002 SLK32
2005 CLK320 cabrio
2003 ML350
1997 C280 Sport