I get a steam engine kind of noise from my air pump upon starting the car. After a while, it fades out. Is there any R&R on these things that I can do myself.

Thanks

One more try.

I removed mine, it is only on at start up for a minute or less. There are some good threads on the air pump in search.......
William Rogers........

Q:

The air pump on my gas W126 makes a notable noise at first start in the am, though I couldn't compare it to a "steam engine". More of a loud clicking sort of noise. Last for a min. or so, then disengages.

As I understand it, this gadget supplies supplemental air to the exhaust in order to reduce emissions early on before the system receives the benefit of running closed loop, etc.

Thank you Ralph Nader.

The Air Pump of my 1994 S320 is doing the exact same thing. Is there a way of fixing this?. It seems like if there was something loose or so. In the center of the pulley of the pump there is a bolt and I wonder is tightening this would help reducing the noise. Has anyone tried this?.

I had a 560SEL that did the same thing. I noticed if I lift up the front of the air cleaner it went away. If I pushed down on the air cleaner it got louder. So I just wedged something under the air cleaner and made it stop.

As has been posted before, the air pump has a magnetic clutch that is activated for less than two minutes during a cold engine start. The purpose of the pump is to add air to the engine exhaust when the engine is cold. On a cold engine start, the air/fuel mixture is rather rich and then leans out as the engine heats up. During this minute or so cold start scenario, the pump adds supplemental air into the exhaust header ahead of the catalytic converter. The additional air leans out the exhaust and promotes an after-burn to reduce NOX and SOX (environmentally bad).

Changing the air pump out is an easy task for a DIYer and should take about an hour or so. You should work from below the car and it may be necessary to remove the alternator for access. You can buy a rebuilt pump from Adsit for less than $400. A new pump from the dealer is over $1000!

Usually, the failure of these pumps are in the bearings. If yours is making a rushing sound, you may want to check the discharge hose from the pump..........it may be broken or loose.

Thank you very much for the information!. I am going to try to see if it is the air cleaner, but I do not know where is the air cleaner in relation to the air pump. Could someone please tell where it is located?. I am also going to check the hoses that go to the Air Pump. In case it is non of this, what would be the consequences of disconnecting this pump?. Thank you!

Disconnecting the air pump will violate the environmental permit for the vehicle. And, frankly, I don't know if an inoperative air pump will trigger the CHECK ENGINE light or not. Perhaps someone else can comment on that.

The air cleaner is the big thing on top of the motor. By pushing it down or pulling it up changes the air flow to the air pump.

In my case pushing down made the noise louder and pulling up made the noise go away.

Once the car got warmed up the noise went away on it's own.

Bigmon:

Thank you for the information, but are we referring to the box of the air filter?. I just want to make myself sure that we are talking about the same thing. Once again thank you for the tip!

Yes, the box. The big metal thing on top of the engine.

Thank you! I am going to play with it to see if it makes any difference, but I think it is the bearings.