clicking noise before and after starting engine
 

I have a problem of ticking/clicking coming from my 1985 380sl (120K miles). It seems to come from a unit that is bolted on the top of the front of the engine on the passenger side. I have attached an image of the culprit. The unit has a linkage going underneath the air filter and one wire running to the front of the car. When the accelerator is pushed while the engine is running, I see the linkage move. I'm not sure what this thing is. It says Mercedes Benz 408201/1/5 and 0025458832 VDO. It clicks when cold, and I turn on the ignition (without starting the engine). It also clicks while the engine is running. Does anyone have some advice? Is this something I need to worry about? I do have the CD manual, but don't see anything on this in it, but the organization is a little crazy in the manual.

Thanks,
Jeff

cruise control actuator
 

This is the servo unit that moves the throttle linkage when cruise control is selected. Does your cruise work?

cruise control
 

Sometimes yes, sometimes no. Not sure why? Maybe the clicking sound has something to do with it? Thanks for letting me know what it is, so that I can start dissecting the problem. Has anyone ever heard these things click before?

Thanks,
Jeff

this unit uses input from electronic and vacuum inputs, I have not heard of them clicking, but anything is possible. These are not easily repaired and most of the time can be rebuilt. I would make sure the culprit is not the input ( vacuum - amplifier) before I would tear into it

Thanks! I'll look to see what kind of input it is getting.

Jeff

The clicking would be from the solenoid inside the actuator. You should unplug the unit from the wiring harness immediately to hopefully avoid damage, if not too late already. On my 560SL, the plug is beside/under the A/C dryer, on the vertical piece of sheetmetal on the left side of the radiator, facing the front of the car. Just follow the wire from the unit...
I had temporarily mounted the cruise amplifier on top of the parking brake bracket for testing, and the wiper linkage punched a hole in the casing when the wiper motor was turned on, creating a short in the circuit and making the actuator click wildly. I'm sure this isn't your situation, of course, but it illustrates the connection from the cruise amp.
I would say that your amplifier is probably toast, and maybe your actuator as well. If you are electrically savvy, there is a fairly good test program you can run to see what the condition is of your actuator and amplifier. GDL has the website and here is the link to their test programs: http://gdl-online.com/testproc.html Good luck. :)

I think there is just one cable (electrical) that goes forward toward the radiator. I haven't driven the car since noticing the clicking, and will certainly remove the cable before driving. Also, I'll check that test procedure. Thanks! Jeff

I have one laying around if you find a need

Hi Ron,

Thanks! I am hoping to get busy on it this weekend. I appreciate your offer for the spare. I'll do some diagnosing and get back to you on it.

Thanks,
Jeff