For my 1990 300SE (gas) Mercedes, it's been suggested I clean my EGR valve to help with the NO2 levels (it's failing emissions). I was told to use a coat hanger.
The valve works okay, in that the plunger operates easily. But what about "cleaning"? There appear to be only two holes: One in the side of the valve's metal block at the base, and one in the center of the rubber 'cup' inside the valve where it meets the mainfold. I'm hesitant to just cram a coat hanger in eitehr hole, as I don't want (for instance) poke a hole in some rubber mechanism.
Can someone desribe (in text) how this is done? For example, should the plunger be withdrawn when I'm cledaning the hole?, that kind of thing. Or is there some graphic resource on the Web? Thanks.