The thermostat housing on my 94 M104 has a small, thickened flat spot on the top. Any reason why I should not drill and tap a hole and insert a bleed screw to release any air pockets?
regards,
Mark

That, I'm not sure. It is interesting to wonder about air in cooling system. I was concerned about air-in-system after removing a radiator one time. I drove my car with the cap "loosely on" for .5 day. I'm not quite sure why I did that, I just thought it was the right thing. I did sleep better thinking it should've helped.

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JHaburay

1972 280se 4.5 "princess"
1986 2.3-16v first 100 (099) USA

Nothing wrong with the basic concept.
Make sure you have enough clearence to the thermostat housing.
Not sure about your car, but some make of vehicles come with a bleeder valve installed, because they are very diffcult to bleed air from after draining/refilling the cooling system.

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2007 C 230 Sport.

I read on another thread about drilling a 1/16" hole in the thermostat itself. Author is passionate about it.

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JHaburay

1972 280se 4.5 "princess"
1986 2.3-16v first 100 (099) USA

M104 thermos already comes stock with a built-in bleed hole/valve , along with instructions to mount the thermo with the hole at the highest rotational spot..

104 air bleed can be done by simply squeezing the top hose a couple of times w/cap off.