Technical What does this valve do?

stevieg32 · Sep 20, 2017

I want to replace the thermostat housing before i refit the head but cannot find one with a fitting for the pipe to this valve,what does it do? Can be deleted? Is it only for the Swedish market as i have a spare Uno 1.3 motor which has the same valve on it.

s130 · Sep 21, 2017

I've no come across this configuration before but I have an idea.

You do not say where that steel pipe with bulbous end (diaphragm/one way valve/?) connect to. Also what is behind the union on the thermostat body?

Given Sweden, cold weather starting and their traditionally lower emissions regulations back in the 80s then I would think that this is part of a regulation mechanism to assist engine and carb warm up.

Does the remote end of the pipe connect to a vacuum (car / manifold) union or another water pipe?

g8rpi · Sep 21, 2017

I think that may be a tapping for throttle body heating water jacket. As S130 says where does the other end go?
You may be able to drill and tap a "standard" housing or get an engineering company to do it for you

stevieg32 · Sep 21, 2017

s130 said:
I've no come across this configuration before but I have an idea.

You do not say where that steel pipe with bulbous end (diaphragm/one way valve/?) connect to. Also what is behind the union on the thermostat body?

Given Sweden, cold weather starting and their traditionally lower emissions regulations back in the 80s then I would think that this is part of a regulation mechanism to assist engine and carb warm up.

Does the remote end of the pipe connect to a vacuum (car / manifold) union or another water pipe?

The diaphragm end goes straight into the air filter,so the water travels along the pipe to the diaphragm/valve but does not recirculate,no idea what it does but it could be to do with cold starting in a Swedish winter.It's only going to be used as a summer car so i think it will be o.k blanked off at the head with new thermostat housing.

jackwhoo · Sep 21, 2017

Sounds like the diaphragm may be meant to operate a flap that controls whether the air entering the carb comes from around the exhaust manifold or cold air from elsewhere , depending on engine coolant temperature. The Idea is to prevent carb icing in cold weather.
If that's the case and it's a summer car then blanking it off should be fine.

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Technical What does this valve do?

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