Hello,

Is this some kind of blow off valve. Air escapes it when I stop, making a trumpet sound. Is it there to release the vacuum from the engine?



The thing in the middle of the photo with the open end. Hose coming in, nothing going out.

 

If it’s exhausting air there, the air bypass control valve or one of the thermactor check valves is bad. Or a combination of..

 

Thanks! That's something I can look into.

Yes. It sounds like a horn for quite a bit after I turn off the truck. Air comes out of the end of that piece. I took a video.

 

Is that different than the Idle Air Control Valve? I just changed that last week. It was doing this before also though.

 

It appears this is on a 90-91 vehicle.
If you trace the hose attached to it ,it most likely comes from the AIR (it's name) Pump which is belt driven. . It also could be a muffler or check valve. That air supply should go to one of the valves of the Thermactor system, Ford's name for the emission control system. I believe there is a hose missing from that component to the other 2 valves.
If there is no picture on the radiator support showing the routing of the hoses,maybe Hayapower can supply one.
It was a somewhat complicated system, but it got the engine passed by the EPA./DEP
If not too much was removed or disconnected there are a few check valves , a Diverter valve and a By-Pass valve in the system.
Would be helpful if you told us the year, and engine size of your vehicle.

 

Back in the day, the air pumps would intake air from an plastic impeller just behind the pumps drive pulley. Most of them were mounted down low on the engine so dust/water would be ingested by the pump failing them in short order. Later, the pump/s, depending on engine, were mounted up higher and/or had closed system intakes (no more impeller intake). The intake was left open like yours pictured..
IAC is different from the Air Bypass/Diverter valve..

 

Thanks for all of the info everyone!