Whats that thing?
 

While changing and idle control valve, i noticed that on the left side of the motor, on the bottom by the crankcase, is a thingy, looks like some sort of pump or motor that is supposed to be driven by a belt from the crankshaft pulley, but the belt is missing, and looks like it has been missing for a while by the looks of the rust on the pulleys. It has a couple hoses coming of it, primarily one hose that goes to the intake manifold. Can anyone tell me what this is? What affect does it have on the motor or intake air if any? If it does have an affect and seems to be an important piece of the motor, i would like to throw on a belt for it. It looks to be the same size as a starter. If anyone can tell me what this might be, i would really appreciate it.

1985 500 SEC

Thats your air pump.
I belive it's there to reduce emissions.
Is this car new to you? Maybe the original owner removed the belt because a bearing in the pump has failed. It seems to be fairly common. The one in my car is on it's way out and I've been thinking of removing the belt myself.

Air Pump?
 

Yeah, i've had the car about a month. Im not a big mercedes techie, but know the basics. Is there any affect on the idle, accelleration, gas mileage, etc. with this pump disconnected? I've been fiddling around with a slightly rough idle, could this pump have any affect on the idle?

Air pump function on these is pretty simple. It runs during cold engine conditions to aid heating the cats.


Joe

What's that thing!
 

I have a 380 SL. If you look closely, there may be a vacuum line attached on the back side of one of the hoses that is attached to the side of the air pump. If this is disconnected, it may create a vacuum loss that could impact other components. Mine was disconnected and I had a similiar issue. Plugged it back in and my problem disaapeared.