Correct sequence for thermostat install

[mbzr4ever]

Can someone please enlighten me on the correct order of the parts to replace the thermostat?


There is an arrow on the t-stat (old one had a small hole in same position) - points up?

I did not know to order a new t-stat housing gasket and will reuse the old one until I get the new one. It appears to fit around the t-stat, because there is a slot.

So where does the new o-ring go?

This is for my 79 240D. Took the old t-stat out, looked like the original, did not look bad except for some lime scale and superficial rusty spots. I guess I'll keep it for a spare.



Edit: I looked at dieselgiant's tutorial, but he did not use the o-ring, just a new housing gasket. He also drilled a bunch of holes in the new t-stat - I don't think I need to do the same.

http://dieselgiant.com/thermostatreplacementandmodif.htm

Inside the housing had more lime scale, scraped it off. Wish I had some citric acid to do a full flush. As it is, I'm planning to flush with distilled water about 9 times, because I could not get the engine block bolt off.