A.I.R. KAPUT

[vincelc]

My 85 GMC 5.7 engine's upper A.I.R compressor froze up a while back. There are no longer emissions tests in my state so I just removed the compressor belts and have kept driving as is.

Can any harm result from this?

 

[Rusty Nail]

The catalytic convertor efficiency will be reduced resulting in more noxious exhaust and I believe engine cold operating temperature operation/ efficiency will suffer some but she'll eventually warm up.
Worse things could happen but The General didnt put it there for no reason.

 

[SirRobyn0]

You will likely get a lot of opinions on this, but here's the facts of how the air system works. It pumps air into the exhaust manifold, where it mixes with the exhaust gases, then it goes down the stream into the cat. Having the air mixed in there helps the cat to burn off the bad stuff and also helps the cat reach operating temperature faster. I tried running my truck without the air pump and the amount of exhaust smell was greatly increased. As @Rusty Nail just said NOx emission will go up as will other emissions, the important thing of note is that NOx is very good at destroying lung tissue. If you happen to have breathing issues then this is very important.

 

[Bextreme04]

While all of this is true, the A.I.R system is there to overcome the limitations in old catalytic converter technology. If you don't have a cat anymore, or upgrade to modern honeycomb catalytic converters installed closer to the exhaust manifolds, you don't need or want the AIR system at all anymore. The older pellet style cats were really hard to heat up and not very efficient. Injecting the unburnt air into the exhaust right after it exits the port allowed a rich mixture to continue to burn after it left the port and heat the cat up more. It also burnt off any unburn mixture before it made it to the cat to keep it from getting clogged and further reduce emissions.

 

[SirRobyn0]

While all of this is true, the A.I.R system is there to overcome the limitations in old catalytic converter technology. If you don't have a cat anymore, or upgrade to modern honeycomb catalytic converters installed closer to the exhaust manifolds, you don't need or want the AIR system at all anymore. The older pellet style cats were really hard to heat up and not very efficient. Injecting the unburnt air into the exhaust right after it exits the port allowed a rich mixture to continue to burn after it left the port and heat the cat up more. It also burnt off any unburn mixture before it made it to the cat to keep it from getting clogged and further reduce emissions.

All of this is true too, but I'd like to add that I do have a modern high flow honeycomb style cat, but it is located in the factory location just after the Y-pipe. It was obvious by the smell that with the air pump disconnected the cat was not working as well. Actually I should clarify, it was obvious it took longer to warm up and if I sat in traffic long enough it was obvious it would cool enough to drop out. I did not like that and was unwilling to make the needed changes (and expense) to go to dual cats closer to the manifold. Even if you are not running a cat there are some benefits as it will help burn off anything not burned in the combustion chamber. There were factory vehicles with air pumps but no cats earlier on.

While I'm against emissions equipment removal myself, it is noteworthy to mention that, it will not hurt the engine to run without the air pump.

 

[idahovette]

Not ALL systems with A.I.R pumps had catalytic converters. It was NOT initially designed to help Catalytic converters operate, just to help "lean" out the exhaust gases from the engines. First one I saw was on a 65 or 66 Bel Air with a 283, a few years before Cat converters........and @SirRobyn0 you beat me to it....great minds and all

 

[SirRobyn0]

Not ALL systems with A.I.R pumps had catalytic converters. It was NOT initially designed to help Catalytic converters operate, just to help "lean" out the exhaust gases from the engines. First one I saw was on a 65 or 66 Bel Air with a 283, a few years before Cat converters........and @SirRobyn0 you beat me to it....great minds and all

Yes, but you explained it better. I was struggling to remember when the first AIR systems came out. For some reason what sticks in my head is the air systems used on the Scout II without a cat. IDK why, it just does.

 

[Craig 85]

I've had 2 Squares w/o factory cats and both had/have AIR injection. First was a 77 K5 with a SBC 400 and HD emissions. Second is my 85 K30 with a 454. Both ran regular fuel.

 

[idahovette]

My first experience with an A.I.R. pump was on my brand new 1968 ChevyII,275 horse 327, 4 speed,12 bolt. Anything above 4000 RPM would cause the belt to fly off. Finally figured out the pulley was on backwards. Offset was just enough to dislodge it at speed............there was a LOT of speed!!! Didn't stay on the car to long, pulled the pump and the tubes fairly quickly

 

[vincelc]

My 85 has no CAT.

What I have noticed is that it runs rougher when I accelerate at cruise speed and when I climb hills.

It accelerates just fine from stop signs and fuel economy hasn't changed at all.

Don't know if an inop A.I.R would effect acceleration at cruise speed--not much info about A.I.R so far when I have googled it.

When I check the troubleshooting charts for emissions and drivability, it seems to point to the EGR for the current symptom. I haven't had a chance to dig into it yet...

 

[SirRobyn0]

My 85 has no CAT.

What I have noticed is that it runs rougher when I accelerate at cruise speed and when I climb hills.

It accelerates just fine from stop signs and fuel economy hasn't changed at all.

Don't know if an inop A.I.R would effect acceleration at cruise speed--not much info about A.I.R so far when I have googled it.

When I check the troubleshooting charts for emissions and drivability, it seems to point to the EGR for the current symptom. I haven't had a chance to dig into it yet...

The AIR system should not effect runability.

 

[ali_c20]

My 66 Impala has AIR system, it's a California car.

 

[Conejo_K10]

It's my understanding that the a.i.r is used to cool the exhaust valves.
Higher cylinder head temps reduce emissions, which then impacts the valve temperature.
I disabled the a.i.r on my 66 Chevy and didn't have any valve issues. Although other tuning reduced the head temperature.

 

[Turbo4whl]

My 1974 350 had an A.I.R. pump and no cat also. The long tube Hooker headers I added shortly after I got it had no pump ports. So the "smog pump", we called them, was gone.