Roland

Hi ! -I´ve got a ´92 Mercedes 300 CE-24 and am wondering about that air pump on the picture, or what ever it is. Who can tell me what precisely this is and what it does ? It´s making a whining noise all the time, as if some bearing is dried up inside it. I removed the belt and turned the pulley by hand. There´s no mistake, the noise is coming from this pump. It´s rather irritating… having this sound, so I´d like to know what my options are..
-Thanks.

Gregs210

They were used by car manufacturers to meet emission specs before engineering and computers made them obsolete and your car is right in that zone. If you live in a state with emission testing you'll have to replace it, but you can probably rebuild it if you're mechanically inclined. There's not too much to them, as long as it's not the impeller making the noise (and 90% of the time it's the bearing). They're easier to rebuild than an alternator, so if you're handy it should be an easy task.

BTW, the car will run fine without the air pump, so if you don't need the drive belt to run another accessory, you can leave it disconnected until you find a replacement (or time to rebuild it). Of course you may get a malfunction indicator from Mother Benz...

Take care and enjoy the ride,
Greg

ZorroAMG

I had the same issue with my smog pump on my M103. Disconnect it first and if it still whines and the bearing is eff'd, REMOVE the pump and put a shorter belt. If the bearing seizes you are going to replace your engine.

I've had mine removed for over a year....

E320BENZ

mine is making the same noise... they told me it was the pump, I'll replace it OEM it's only $1200.00 new i'm crazy like that

MB Tech - USA

Sometimes you can get just the bearing from the aftermarket, much cheaper. If you disconnect it/remove it, the check engine light will come on if your vehicle is equipped with one, but it will not effect your engine performance.

Roland

Thanks for the replies, all of you.
-Well, I suppose I´ll see if I can rebuild it. I tried oiling it, between the pulley itself and the static part in the centre. Kind of hard getting oil there, but the noise was reduced slightly. But I´m afraid that´s only a temporary solution..

After I first start it cold when the pump is pumping, the noise is much less. But then in some 40 or 50 secs, there´s a “click” and the pump stops pumping. Then the noise gets louder.

-Anyhow… a bloody weird system… - pumping air into the exhaust… hmm..
What on earth for ?? -Because if I´m understanding this correctly, pumping air into the exhaust doesn´t reduce or lower any hazardous gases produced by the engine´s running. It simply adds fresh air ainto the exhaust manifold, resulting in a lower percentage of the hazardous gases measured at the tailpipe....

-Or am I not understanding something here...

But thanks again.

Brian Felts

What size is the shorter belt you could use. I don't have any cats anyway and we do not have smog.


Brian

mhorn

I had the same issue with the air pump on my m103 motor. It would whine at any given time. Thought i was going to have to replace it, then it magically stopped squealing. Don't know why, didn't do anything to it. I haven't heard a peep from it since and that was about 9 months ago. I think the reason for the air pump is to allow more oxygen to bond with the exhaust via the platinum in your cat. converter so you get more CO2 instead of carbon mon-oxide while the engine is cold.

Roland

That´s nice. I wish mine would magically stop whining too..
-That explanation with the air for the catalytic converter sounds logical. Hadn´t thought of it that way before.
-Stay cool..

mhorn

yeah, I would like to just remove it but I don't know if it would pass inspection with out it. Also don't know what length belt I would need without it.

DougE280 in UK

Mine too is making a whining noise, so I would like to try running with the air pump disconnected to see if this is the cause.
How do you do this?
Do you physically have to remove the air pump from the car?
Isn' the belt too long without this pulley installed?
Does anyone know if it'll pass a UK MOT test without an air pump?
Thanks,
Doug

Gregs210

if you can find the parts. Basically inside the thing is just an air compressor, so if you can find bearings, etc. and lube everything it should work great.