89 520 thermostat replacement

[plainzwalker]

i was just wondering how difficult it would be to change this out? ive done it on a camaro, but that was just a matter of unscrewing 2 bolts and swapping it out..it looks a lil more difficult on the bmw.

thank you in advance
plainz

[Ringo]

The thermostat is at the end of the top hose that goes to the engine, kind of like on Chevys, the diference is that it has 3 bolts and sits sideways, so you will need to drain the coolant slightly. Be careful when you restart the engine that you vent the passages of all air bubbles! The 10 mm head screw that screws into the thermostat housing should help venting a bit. Have fun

[plainzwalker]

okay...i got a thermostat, my question is, can i reuse the black O ring off mine or do i need to get a new one? also, how do i go about getting the air bubbles out? do i need to run the engine without the screw in?

thanks
jeff

[Ringo]

I have reused my o ring twice, as long as there are no visible scars and if its not cracking it should be fine. But to vent you must just loosen the bolt 2 or 3 revolutions when the engine has warmed up until antifreeze comes out instead of foam liquid. Then with the engine idling open the reservoir and pump the hose that goes to the top of the radiator, you can feel the air bubbles with your hands as you squeeze and whe you don't hear them or feel them you can stop. After a week of driving I like to loosen the thermostat bleeder bolt after a long drive from work just to see if there are any more bubbles lurking. Then it should be fine, those heads are tough for driving but if there is air leaving a hot spot in certain spots of the head they could crack.