W126 Power antena

[MS Fowler]

I am anout to go junkyard hunting for a power antenna for my 1982 300SD. Can anyone provide any information about how to tell if they are good without being able to make it run? No batteries are permitted in the junkyard, but I will have a digital multimeter. Are there some ohm values that should be present across certain pins?

[Ken300D]

All I can think of to tell you is what you probably already know - the most predominant failure mode is when the little tiny drive belt breaks. Then the motor runs for a few seconds but nothing happens. The next likely failure mode is the antenna shaft is bent or otherwise siezes up or down - then the belt breaks.

Either of those two failure modes are fairly easy to repair if you have a unit with good motor and electrical connections and components. Sometimes water gets in the electrical area and corrodes the board, but this can often be cleaned off and resealed.

Not that easy to get the motor unit apart, but it can be done. Then you can replace the belt and lubricate the moving parts. (Antenna shaft is installed into an empty motor unit after the motor unit is back in the car.)

Hope this helps -

Ken300D

[Oilbrnr]

Having just torn mine apart, I'd say that it would be impossible to tell if they were good or not without either disassembly or testing operation with 12v.

If you see one with the mast part way up, or even all the way up, I'd shy away. The belt could be broken, or worse like mine, it had been operated so many times with a bent mast that the driven worm gear was shot. The teeth were so worn they would no longer engage in that portion of the rotation.

I suppose that if you were able to get a couple of them, you could scrounge enough parts to get one that works.

Realize that a real Hirshmann replacement is about $55, and should provide many years of trouble free operation. Oh and just a new mast for the OEM unit is ~$35...

[Ken300D]

It's highway robbery on the little belts too. I've seen $14 quoted.

Ken300D