Understanding the m10 thermostat

[lovemybmrs]

1981 320iPulled out my t stat to test can someone explain to me how it flows and the ports in the tstat please help

[Reck]

It should only have 3 outlets? Just to be clear, no. 3 on this diagram right?

http://realoem.com/bmw/showparts.do?mod ... g=11&fg=35

Flow from the rad opens on the bottom port when 80c is reached. Obviously it bypasses the rad completely when shut.

TBH, you're best replacing than testing. You can get a new thermostat for a tenner. Might aswell do the water pump while you're there. Rad out (reverse flush while it's out), remove fan, water pump lives underneath the pulley. A 2 hour job at the very most!

[lovemybmrs]

Soo don't know of this makes any sense but mine when I heat it up closes the port to the lower radiator and when it is open it isn't open much

[Reck]

Weird. Don't take my advice as gospel though, that's just I assumed how it worked. You haven't got it on upside down?

[lovemybmrs]

I don't believe it is installed incorrectly

[Reck]

I'd still suggest getting a new one. It's not worth risking your whole engine for the sake of such a cheap component..