Thermovalves

[mephi]

Question: What are the thermovalves and thermowax valves, where is each one located, and how do they function?

[2ndGenGuy]

Thermovalves open and close vacuum flow based on the temperature of the coolant at the location they're inserted into. So when the temp gets to X degrees, thermovalve A opens an allows vacuum to pass to some sensor or device.

I believe there's one or two on the back of the intake manifold, and maybe one on the thermostat housing. There should be a FAQ around here somewhere with their exact locations.

[mephi]

I looked, but I couldn't find it. Hence the post. If someone could direct me I would appreciate it.

[Pico]

http://img.photobucket.com/albums/v337/picopop/VAlve.jpg
Here's a pic of the valve.
You can also download thehttp://www.3geez.com/forum/newreply.php?do=postreply&t=67337 manual here http://www.3geez.com/forum/showthread.php?t=25137

[mephi]

The manual doesn't really go over the function of the thermovalves on the back of the manifold--the ones used for vacuum control at different temperatures. I'm trying to figure out which port does what on those things, and at what temperature.

[2oodoor]

Mephi if you DL the manual there is a section under carbs that gives schematics to several different applications. If you find your application it shows the thermovalves you should have.
Basically they switch vacuum or electrical signals via the temperature of the coolant port in which each is located. Some are default open and close at engine operating temp, others may default closed and open at operating temp.
These are no big mystery by no means, you will find them under the hood of just about any make car there is (beginning in the late 70's). Most you will find on or around the thermostat housing or on the intake manifold. On average they control/limit distributor vacuum advance, carb secondary operation, EGR bypass, EVAP and choke pulloffs.
Not as many are found on modern cars because one sensor (or two) is used to signal ECU, and because EFI cars just do not need them. There are a few models that still use one for various emissions devices.

[mephi]

Thanks for the reply. I found them and I figured out how they work, I'm just wondering of the two on the back of the intake manifold, what temperatures do they open at and which ports are open at those temperatures?

From what I understand, on the one that has three, one port is open at start up, one is open at operating temp, and I guess the other is the vacuum source. If I'm wrong please correct me.

The other one I'm not really completely sure.

[2oodoor]

Once you see the diagrams for you application you may be able make a logical understanding of purpose. The one with three, well the third one would have to be bypass or pass thru which could just as easily be done on a tee somewhere else so, ha, this is the craziest controled carb set up I ever ran across personally.
As far as what temps, I would think it would be just thermostat rating and below, such as 190, 160 etc and below. Below would be off and thermostat opening would say the engine is near or at operating temp so the thermowax valve would be active. I cant imagine them having some wierd in between temp range but with the wierdness of it all it would not surprise me.

[mephi]

Well, since I have a Weber 38 now, I don't care what they do. Muwahahaha!!!

[2ndGenGuy]

Good work! Though you can use them to do other tricks too! ;)

[greentee76]

Well, since I have a Weber 38 now, I don't care what they do. Muwahahaha!!!

Yeah I used to know and know I have the info written down somewhere, but like you since I went Weber I don't care anymore! ;)