Little hose on thermostat housing

I am building up my AJ16 after a restauration, a small rubber hose must be connected to the thermostat housing (maybe the bypass valve disk?) ; but where is it coming from?

Thanks for your support, greetings, Rudy, Holland

Are you talking about the one that disappeares off to the right under the manifold?

It goes to here, in between them manifold and the fuel rail:

It’s the one coming in from the left.

Hi Harald, yes that’s the one, and the other one, were does this go to? And what is the function of these hoses anyway?

Many thanks, Rudy

I think it goes to the throttle assy?


The other one coming from the thermostat? That is the bleeder hose going to the expansion tank.
Or the other one on top of the inlet manifold? That goes to the throttle body and is for throttle body heating. To be honest, I don’t know why it goes there via the inlet manifold.

I found how en why it works. That thing on the inlet manifold is a Part Load Breather: see

Thanks for your support, Gruss Gott, Rudy

Thank you for sharing this!
Very interesting, some BMW engines have problems with frozen crank case breathers. It’s a good idea to heat this.