That machine shop sure Stuck it to you!!! Compare that to a set of Bowtie Aluminum Heads complete valve job for around $200~ And that is from a Speed Shop! Which includes surface grind to clean head mating surfaces.

Obviously you didn't check around. Doesn't matter if it is a Mercedes head or a set of Chevy Bowtie Alumimum Heads. Must be nice to have money to donate to machine shops that want to charge high dollar.

And on top of all that, you never got a double angle grind on the valves/seats - higher performance and better performance for higher compression engines! 13.5:1 and higher

And why would you replace the valves? Were they burnt so bad they couldn't be ground? That was a pure waste of money!


As for thermostat - a flat washer with a 3/8" hole will keep an engine cool for circle track racing which is a lot more strain than you'll put on your car. If it still is too warm, drill out to 1/2" hole.
Is your fan in the right place? If the fan blades are too far back into the shroud it won't cool very well and same is true if towards the engine too far. For maximum effectiveness, the center of the top of the fan blades should be at the edge of the shroud. (half of blade hidden by the shroud)

Are the fins of the raditator clogged with bugs/dirt? or bent?

AutoZone is a very cheap place to buy a lot of your Mercedes needs!