1978 350 temp sensors and vacuum lines.

[ryan_289]

How many temp sensors should my 78 350 have? I can only find one wire but I have a sensor down by the drivers side spark plugs and my thermostat housing has 2 sensors in it. One button head sensor and one plug in sensor.

Also, right beside the thermostat housing I have a vacuum tree that screws into my intake. It has 4 ports on it and they are all open. Are these supposed to be plugged into something or just capped off?

I suspect that the "engine rebuild" the PO told me about was an engine swap.

 

[1987 GMC Jimmy]

How many temp sensors should my 78 350 have? I can only find one wire but I have a sensor down by the drivers side spark plugs and my thermostat housing has 2 sensors in it. One button head sensor and one plug in sensor.

Also, right beside the thermostat housing I have a vacuum tree that screws into my intake. It has 4 ports on it and they are all open. Are these supposed to be plugged into something or just capped off?

I suspect that the "engine rebuild" the PO told me about was an engine swap.

Can you post some pictures? You should only have the temp. sender on the side of the cylinder head. On the feedback carbureted cars and trucks, there's a Coolant Temp Sensor that threads into the water neck in addition to a thermal valve switch (TVS). However, yours shouldn't be that. Now, someone might have pulled parts off a CCC truck or car and just used them on yours. In that case, that sensor and others like it if present would be doing nothing. As far as the vacuum tree goes, that should be capped for now unless you figure out that stuff should be plugged in there. Most of that stuff comes off the carb, and cruise and HVAC usually get their vacuum from a port on the center-rear of the intake. If all your vacuum operated components are accounted for, I'd plug up what you don't need.

 

[ryan_289]

I will try and get some pictures tonight. This truck has cruise but does not work and the quadrajet has been replaced with an Edelbrock. Im not sure if I have the egr or efe stuff.

 

[1987 GMC Jimmy]

I will try and get some pictures tonight. This truck has cruise but does not work and the quadrajet has been replaced with an Edelbrock. Im not sure if I have the egr or efe stuff.

That's okay. It doesn't matter too much what you have or don't have. The most important thing is that you don't have vacuum leaks, and everything that you want to work does. If the rubber on the cruise servo isn't busted, you may be able to get that working pretty easy if you wanted.

 

[ryan_289]

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[1987 GMC Jimmy]

Oh, yeah. That stuff doesn't apply to your truck. You can leave the coolant temperature sensor and that other thing on the water neck alone. Is everything that needs vacuum getting it as far as you can see. If so, you can plug those ports coming off the manifold and anything on the carb that's not being used should there be anything.

 

[ryan_289]

None of the vacuum lines are hooked to the cruise. pcv is hooked up and vacuum advance is hooked up. Ill probably take the vacuum tree and the sensors out and replace them with plugs.