I have an 84 Dodge D150 318, auto trans, 2bbl carb with emissions. Im trying to get the vacuum lines right on it because the previous owner kinda screwed them up I guess. On the drivers side of the engine block there are two vacuum ports. One has two outlets and controls the egr valve. the vacuum diagram I was looking at showed that one goes to the carb and the other to the valve. The second port im not so sure about. It has three outlets and it wasn't pictured on the diagram. Its not connected to anything and I was wondering if anyone could tell me where the three ports connect?
Speed Dragon
05-12-2009, 09:11 PM
Can you get a pic?
Ronb2285
05-12-2009, 09:31 PM
Ill try to get one up tomorrow. thanks
Ronb2285
05-13-2009, 04:34 PM
Here's a pic. There are three ports and I dont know where they go
Speed Dragon
05-14-2009, 03:23 AM
One is gonna be the vacuum inlet, ie should be hooked to manifold vacuum. The others will run to whatever equipment it runs if you still have it. I think one goes to the air cleaner, the other to the smog pump or something.
Those pieces are called thermovalves BTW as there are opened by coolant heat.
Also, the EGR valve should be run off a solenoid IIRC, not right off the thermovalve.
Ronb2285
05-14-2009, 02:09 PM
Thanks for your help! Should the thermovalves be capped off or is it fine to leave them the way they are?
Speed Dragon
05-14-2009, 08:04 PM
As long as you don't have vacuum run to them, it's fine to leave them as they are.
Oldblue1978
05-16-2009, 05:26 PM
yep, temperature regulated ported vacuum switch, "in the field", as they are called. It appears to have been painted over, but most of these were color coded for specific temperature ranges and types. some opened when cold and shut off when hot and others opened when hot and are closed when cold. typically the one close to the thermostat was for the EGR or distributor vacuum advance, also the AIR pump diverter valve. The EGR valves were activated via the thermal ported vacuum switch during cold operation because that is when an engine runs the richest. Not needed when fully warmed up, so it closes. If your motor has a vacuum aplifier on the back of block, sometimes those are supplied vacuum from those, which supplies a stronger vacuum signal to the EGR valve for more precise control for smoother engine operation. Others are mounted on the top tank of radiator. Also some of them are 2 port.
