Chev steam valves
 

I am working on a '43 HUP and was hoping to reach a consensus about the steam return system. The pictures and books just show a line coming from a fitting in the rear of the cylinder head. My engine has a small pot metal valve at the head fitting marked Binks No. 57? The story is that you opened this on steep dissents to relieve trapped steam in the rear of the head. I have a hunch that this valve was added as it is covered in brass parts and the idea of it being accually used is unrealistic. Anybody know?

Yes the steam releaf are used.
 

I can tell you from experience that they can be used and probably were used more of the CMPs that on CCKWs. Most if not all CCKWs had the same steam relief valve but toon them you have to stop the truck open the hood and climb in to open the valve. On the CMPs on steep down grades when the engine temperature starts climbing toward 220 you open the engine access door and burn your knuckles opening the valve. As soon as you do the engine temperature starts going down.

With my HUP on steep climbs, there never has been a temperature problem as soon as you start down a steep grade though with the engine holding you back the temperature starts to climb. The valve only needs to be just open a crack for the system to function. Of course you have to close it once you are on the level again.

When I say steep I’m talking about where the Jeeps are down in low range. People are always impressed when they see a CMP climbing up behind a Jeep.