I replaced Idle Speed Control Unit and Air Slide valve. The Air Slide Valve is buzzing and there is a relay right next to the OVP that is quite hot. The part number on the relay is 001 542 02 19. What would this be for? Could replacing it help?

Steve
’85 500SL Euro

That relay is a generic current carrying relay. It is used in many systems. There are probably four of those relays around the car. I do not think they are involved with idle control.

They often get hot so I wouldn't condemn it for that.

That relay is a generic current carrying relay. It is used in many systems. It should have five round pins and be a silver cube. There are probably four of those relays around the car. I do not think they are involved with idle control.

They often get hot so I wouldn't condemn it for that.

What's the buzz?
 

Okay Steve

But have you ever experienced an Air Slide Valve Buzzing? Any idea about this?

Steve
'85 500SL Euro

Well thats a good question as the proper function of the valve is to "buzz". You usually don't hear it but the valve is controlled by what is called pulse-width modulation. The means that the valve is openned and closed at an exact frequency. It is openned and closed by changing the duty cycle. The duty cycle is the relative time the valve is closed versus open. I have always presumed that although the valve receives the open closed siganl completely at a large frequency that the valve actually kind of hovered at a constant spot; sort of the average of the resulting strength of the pulsed signal. The valve may be dampened internally to keep it from actually moving as fast as the signal. If the dampening is missing the valve might actually move as fast as it is signalled. This would in effect do the same thing.

I think that I would have to hear it to do better than that.