View Full Version : AIR Pumps

08-27-12, 12:19 PM
I'm in the process of restoring a 1973 Coupe DeVille. After cranking the engine the other day, I noticed that the belt that links the AIR (smog) pump to the fan was so loose that it was not turningt the fan. I tighted up the belt by adjusting the AIR pump and it seemed to fix the problem. However, when I tried turning the AIR pump by hand, I found it very hard to turn. It took quite a bit of effort just to get it to move. My question is should the AIR pump turn freely, or is it supposed to be hard to turn by hand? I'm about to take the Caddy for a 100-mile drive and I want to know if I should replace the AIR pump first.

Thanks for any advice.


08-27-12, 12:54 PM
I don't know how well it should turn, but I would just remove it altogether. Even if you live in California like I do, for a 1973 you don't have to smog, so there's no reason to keep it unless you want to be totally original.

08-27-12, 06:58 PM
Remove the AIR pump (and bracket if you can) and crimp/plug the fresh air piping to the cylinder heads. Common practice on '67 -'68 Merc Cougar Hi-Po engines.

A good AIR pump will spin pretty easily with a slight rattley-clattery noise - it's a moving vane pump.

The Ape Man
08-28-12, 05:24 PM
The pump should turn fairly easily. Replacements are cheap enough.

If you decide to remove it the fan belts and pulleys from a non-A.I.R. equipped car will be needed.

That will lose the stepup ratio from the crank to the alternator and available current at idle may be less. Consider changing to a more modern alternator if changing the belt setup.

08-29-12, 11:18 PM
It might be eazier to just get a new air pump.. To take off the air pump you need a non air pump crank pulley and waterpump pulley..Being a 73 it has duel belts on the A/C compressor - power steering.. The only year with a non air pump with duel belts is a 1970 model.. So if you can find one GOOD LUCK... Now you coud put on a set of 425 non air pump pulleys from a 77-79 ...To do this you will have to change the A/C pulley and change the power steering pump to a single pulley set-up...some of the pulleys on the power steering pumps won't swap so you have to change the pump... If you have to change the pump you will have to swap the part that the high pressure goes to .. because the hose ends are different.

12-12-12, 12:29 PM
Thanks for the advice, guys. So far, most of the car is original and I'd like to keep it that way if possible. I may try to take it apart and see if I can rebuild it.

12-14-12, 12:15 PM
I have a '79 CDV California car with the AIR pump that I'd like to remove. Does anything here apply to that? What do you use to plug the holes on the heads, and will this affect my alternetor or not, being a '79 that usually didn't have an air pump.


12-16-12, 11:31 PM
Benzilla.. You should have just started a new thread.. But this is what to do.. Most 77-79 caddies with the 425 motor, like yours, came without a air pump.. I guess the cal cars still had them...You will have to find a set of pulleys off a 77-79 non air pump motor.. That is a crank pulley and waterpump pulley..Then just take off the pump and head to head pipe.. Plug the holes in heads with freeze plugs or dimes.. Dimes work fine... Change the pulleys and get a new belt... Finding the pulleys is the hard part..

12-18-12, 03:25 AM
Thank you! And sorry, it seemed more related when I wrote it. What sparked my attention; that I wanted to inquire about, was 'The Ape Man's comment about stepup ratio & affecting the alternator. I wondered if I might have similar issues. My car came with the optional heavy duty generator, and the currant one is 120 amps.

Yes, in 1979 the California 425s had AIR pumps, special lean-jetted carbs, a special distributor with a PITA control box by the charcoal canister, and (on the plus size) a 3.08 rear axle. I'm in the process of federalizing mine, save for the axle.


The Ape Man
02-06-13, 07:27 PM
Man that car must fly and drink gasoline too.

Dorman Products should have a listing for the proper core plug for the A.I.A. passages in the heads.

If your crossover pipe/check valve is still good someone here might need it. Those are hard to find.