FWD HT4100 air pump pupose?

It is part of emmision (smog) control. It is used on my 85 Eldo to inject air to either exhaust manifold or to the cat converter (depending on the driving conditions). That added air makes the exhaust cleaner by helping the cat converter in burning leftover fuel.

You can get rid of it but your car will most likely fail emmisions iinspection (if there is one in your state).

Peteski

If you're never going to use the A/C then you might consider getting rid of it.
Without it, you will never get enough tension on the belt to keep the A/C compressor spinning while it is operating.
Far better option would be to get another one from salvage or, heaven forbid, a new one. Keeps the world and your A/C pump happy too!

Isn't he talking about AIR pump and not AC compressor?!

Peteski

Yes, but the smog pump is responsible for keeping the belt wrapped most-of-the-way around the A/C pulley. Without it, there will be LOTS LESS belt contacting the A/C pulley, and not enough to force the spin if the compressor kicks on...

Unless the belt is routed WAY DIFFERENT than on my FWD Deville.... which I doubt.

I decided not to screw with it, the bearing noise goes away when warmed up, sometimes it is not there when car first starts, but if u rev it, it will start getting noisy. My friend told me to just gut it and keep the pulley, i might do that when the car will come close to finished and is going to be on the hoist. I'll gut it after the emissions test. On the digital cluster, above the milage reading, there is "EMISSIONS", what is the purpose of this on the digital cluster?

That might not work either, if it is the pulley bearing that's failing and not the 'internals'...
But if it IS the guts, it will buy some time, anyway.:yup:
As far as the EMISSIONS indication, I can't tell you right now, because my display don't glow....
Yet.:thumbsup:

we'll see once i start driving, i took it out around my street today, damn, that thing accelerates 3 times faster that my dads P.O.S, and its an IDENTICAL car + subwoofers in the trunk. I have no mods done to the motor yet either. Lays down rubber no prob either! (bad for tranny tho) Thanks for all advice!!

My air pump siezed and broke the serpentine belt on my 87 Eldorado. Replacement air pump was about $60 at Autozone. You might want to change it before it strands you.