I know I'm not the first to say this: If it ain't one thing it's five others!

While servicing my 86 F150 5.8 all original, I noticed that the small belt to run the air pump was missing. I don't know if it has always been gone or if it broke and I just haven't missed it before. Anyway, I stuck a new one on and now it's acting up. I don't know if it's just the pulley or the whole thing that making noise.

What does this pump do and is it completely necessary?

Can I get a replacement pulley or is it the whole thing?

 

Define "completely necessary". Many, many vehicles (not just Ford trucks) of this vintage have had the air pump deactivated, typically by removing the belt.

Few people call it an air pump, by the way. It's usually contemptuously labeled the smog pump. If you're a member of the "rip out all that pollution crap" club, stop reading now and have at it. Your engine might gain a fraction of a horsepower from not having to spin that pump.

If you're still reading, the pump has two purposes:

1) Under certain conditions, it injects extra fresh air into the exhaust to help complete combustion. Less pollution = good, no matter what one thinks of clean air standards.

2) The system sprays cooling air on the back of the exhaust valves. If your truck works hard like mine does (hauling a camper over the mountains), this can make a big difference in the life of the hottest part of the engine.

Not a lot of people know about the second function. If your truck lives a genteel life, it probably won't matter. If worked hard, though, you'll want to keep the system.

As far as the noise, I doubt it's the pulley itself. Most likely the pump is dragging. They are cheap, if memory serves me correctly. If you're getting a high pitched squeal, you could try some belt dressing first and see if a slipping belt is the source of the noise.

 

Thanks for the input.

I'm not of either camp per se... I realize the need for cleaner regulations/standards on emissions but I also think things have gone a bit crazy.

Your point is well taken, my truck is a tool, it works hard sometimes and I intend to work it a bit harder in the next couple of years pulling a camp trailer.

I will check into fixing the pump or perhaps replacing it. It's definitely not the belt, that's new and it's not glazed, so another fix it is.

I wonder what the other people do with their spare time...

 

My guess is the bearings in the pump. Somebody here several years ago explained what they did to cure that on their pump but I don't remember the details at all.

It's officially called the Thermactor Air Injection R-sumthin' (A.I.R.) pump, aka the smog pump and is part of the emissions control system as Karl explained.

 

Air Injection Reaction, aka A.I.R. pump

My TWO pumps injected air into the thermactor ports at the back of the heads AND into each exhaust manifold port in an effort to burn off monoxide and hydrocarbons without using a catalytic converter.

 

If the belt has been off for awhile, check the metal piping and the check valve. With no air flowing through the pipes from the pump, exhaust gas goes up through and forms a acid that sits in the pipes and ruins the check valve, and is a common cause for the pump to rot inside and go bad.

In my area I have yearly inspections and they look for the belt to be on the pump and it's all hooked up, and the catalytic converter to be there.

 

Well upon close inspection last night the culprit is the pump itself. Took the belt off and couldn't turn the pulley by hand.

Did find a reference to rebuilding the pump so I will probably try that this weekend.

Between that and replacing vacuum lines I'll be busy.

I'm not worried about passing emissions at the moment. I still have my permanent Montana plates on the truck and I won't bother with an Idaho license until I get everything going correctly.

I'm not even sure they would smog an 86. Maybe an Idaho member could chime in and tell me.

 

Inspection Requirements
Eligible Idaho vehicles registered in Ada County, Canyon County and the city of Kuna must undergo emissions inspections every 2 years.
These vehicles include:
Gasoline-powered vehicles model year 1981 and newer.
Diesel-powered vehicles over 5 model years old.
Inspection Exemptions
The following vehicles are exempt from emissions testing in Idaho:
Vehicles under 5 model years old.
Vehicles older than model year 1981.
Hybrid and electric vehicles.
Vehicles weighing under 1,500 lbs.
Motor homes.
Classic vehicles.
Farm equipment that is motorized.
Vehicles used solely for agriculture purposes.
Extracted from : Idaho Car Inspection | DMV.org