Air Filter parts

[My78truck]

Cleaning up my air clearer housing and wanted to find out if anyone knew where I can find these parts.....if possible.

Thanks.

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[75gmck25]

The part on the left is the thermostatic air control ( or Thermac sensor ) and its common to many GM vehicles. Its temp sensor controls the vacuum to the small motor that moves the air cleaner snorkel flapper. There should be a parts number on it and it should match a current number if you do a google search. However, folks on eBay seem to think these sensors are made of gold, so you might just test yours and end up reusing it.

The other item is the filter where you connect the hose running down to the valve cover vent for the PCV. I think it’s still available as a standard part. However, you could just clean it up with degreaser and reinstall the same filter. It just keeps oil vapor from coming up into the air cleaner. The air is going from the air cleaner and down to the valve cover, so it should stay relatively clean.

 

[My78truck]

Thanks so much. I looked for a part number on the sensor and could not find one. I will look again.......closer. And so the hunt begins.

 

[AuroraGirl]

The part on the left is the thermostatic air control ( or Thermac sensor ) and its common to many GM vehicles. Its temp sensor controls the vacuum to the small motor that moves the air cleaner snorkel flapper. There should be a parts number on it and it should match a current number if you do a google search. However, folks on eBay seem to think these sensors are made of gold, so you might just test yours and end up reusing it.

The other item is the filter where you connect the hose running down to the valve cover vent for the PCV. I think it’s still available as a standard part. However, you could just clean it up with degreaser and reinstall the same filter. It just keeps oil vapor from coming up into the air cleaner. The air is going from the air cleaner and down to the valve cover, so it should stay relatively clean.

is the thermac sensor a coil of wire... i dont undersand how its powered without a signal to it. it does have a vacuum.. wait.. i cant remember. how does it sense

that other filter can actually be found NOS a lot. some air cleaners didnt use that. dpeends on the system

FB59 is a still made replacement that might fit your housing, some differences were made and the part numbers overtime probably supersceded but still worked in older hosuings so yeah

 

[75gmck25]

Engine Vacuum is applied to one side of the two ports on that sensor, and when it’s cold it allows vacuum to pass through the sensor and be applied to the vacuum motor for the flapper.

I assume there is some type of coil inside the sensor, and once the sensor warms up it must uncoil and plug off the connection between the two vacuum ports. That allows the flapper to move down and the air cleaner pulls in cold air. Just my best guess.

 

[AuroraGirl]

Engine Vacuum is applied to one side of the two ports on that sensor, and when it’s cold it allows vacuum to pass through the sensor and be applied to the vacuum motor for the flapper.

I assume there is some type of coil inside the sensor, and once the sensor warms up it must uncoil and plug off the connection between the two vacuum ports. That allows the flapper to move down and the air cleaner pulls in cold air. Just my best guess.

I accept your logic. I think I have an air cleaner with it broken and missing the top part and the coil, I recall pegs that a coil would mount in and twist about

At least those are the things i tell myself to sleep at night.
Uncomfortable truths are most uncomfortable, must not think them

 

[PrairieDrifter]

Napa has that little air filter for the pcv in stock.

 

[My78truck]

Sooooo, next dumb question. Is there a right and wrong way to reinstall the thermal sensor?

 

[AuroraGirl]

Sooooo, next dumb question. Is there a right and wrong way to reinstall the thermal sensor?

i would think the wrong way only involves the vacc lines

 

[Pmac]

The Thermac sensor vents vacuum as the Air Cleaner warms up - this reduces the negative pressure at the snorkel vacuum motor and the internal spring (in the vacuum motor) opens the door to allow fresh air to be drawn in - the system is a little counter intuitive but it is critical that the door opens as intended, a FSM ( section 6E I think) will have a temperature range for the sensor, and one of those nifty little red dot thermometers is just the ticket for that job.

 

[My78truck]

I have a question about the damper position for the Thermac. I have tested the Thermac with a vacuum tester and it closes with vacuum. So, i need clarification as to the damper position when the engine is started and cold - Is damper open or closed? Mine is open on cold start, so taking air from the stove pipe and outside. Once it idles down, the damper is still in open position. Is this correct? I do not have the air filter in place and the cover is being powder coated. Should I have these in place to verify if working?

 

[Craig 85]

If the engine is cold, the vacuum will close the damper unlit the engine is warmed up. It should only be pulling air from the heat stove, not from the end of the snorkel. Once the thermal switch has warmed up, it should break the vacuum and the damper should stay open.

 

[My78truck]

Hmmmmm, not sure what is going on. I will have to wait until I get the air filter house top back and try again.