85 300Sd alternator...
 

I have been having problems with my alternator lately.

To make a long story short, I have replaced it under warranty twice and it still only puts out 12.5 volts at idle without any load. I I put ac and lights on it goes less to about 12.

I believe this to be inadequate as all electrical systems only function properly when at high idle; Ac blower picks up....headlights are brighter, radio works etc.....

The bosch rebuids I have received are 65 amp alternators. Phil at fast lane says I need an 80 amp(part #1008154490288).

While I believe Phil instead of the idiot at the local parts store, I just thought i'd ask the pro's for another opinion before I go ask for my money and core back.

You would think that 2 local auto parts stores that carry Mercedes parts would have the correct amperage alternator.

Please help, the flickering lights are killing me.

Plantman:confused:

I suspect the rebuilts you are getting are either defective, or you have not connecting the wiring properly. Idle voltage with no accessories on should be in the range of 13.5-14.5 volts. Anything less than this would indicate a defective alternator/regulator. Also try revving the engine up to 2000 and recheck voltage.

Your readings indicate that you are running on the battery. A 65A alternator is probably okay unless you have virtually every electrical accessory on, but you should never go below the amp rating that was original equipment.

Duke

I removed and cleaned the terminal/relay box where the alternator wires go into and then back out to the battery. They were corroded and I figutred that was the ceapest/easiest way to go.

I drove arounf for about an hour and it appears that the flickering has stopped. The ac also is blowing without much deviation in blower motor speed and the radio has not gone on and off like before.

There are however 4 terminals in that little black box and I was only able to get to the two larger ones on the right side as the other two have proven to be a challenge due to rust and/stripping.

I think once I clean those up the problem may be gone.

Any idea what that box is called?

Clean all ground as well as hot wire connections... including battery cables (inside) and battery terminals.

Then ask duke what to do. :)

Duke?

I keep getting conflicting reports regarding the alternator.

Some people tell me it's a 65 amp alt and other have told me an 80 amp.

?????????????:confused:

This applies to my 1984 300SD, but should apply to you also.

The 65 amp alternator (Bosch AL117X) is a drop in replacement for the original stock 55amp alternator. It's what is standardly sold. Don't know if you can still get a 55 amp.

The 80 amp alternator (Bosch AL69X) will bolt in fine but takes a little of "the old finagle" to get it in. When in, you will have a heck of a time getting the belts over the pulley (the larger body of the bigger alternator "uses" some of the low end adjustment for the belts). I had to remove the pulley, place the belts on it, then bolt the pulley back on the alternator after it was mounted. Conti apparently makes ~10 cm.(?) longer belts that would eliminate this problem, but I didn't find them until I was already put back together. Torque the pulley to spec. (a whole lot!) and the shaft has to have the allen key recess for this to be easy.

I really like the 80 amp. in the car; electrical peace of mind.

It is easier than it writes up as.

Edit: and you need to solder and shrink wrap a new little harness (10 minutes, with the wire and connectors handy).