Was this a direct bolt in aside from the belt?

no.
the largest alternator with the stock 3 spade connector the 123/126 diesel has is the 80 amp model.
above that you have to install a larger wire feeder and replace the stock wires.

IF you find a 90+ 124, you can pull the wire harness from it's alternator, and then it's a simple bolt on procedure.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

hay i am looking for a littel help, i instaled a bosh al129x in my 1984 300sd,and i wired it the way it said in the very begining of thred,but the battry light comes on when i turn the car off, any help would be great

There's only two wires connected to the alternator so disconnect them and see if the red light goes out ~ if it does , you either mis - connected the wires on the alternator you bought , is bad .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

i took one wire +side of battry to the bigger lug of the alt and smaller lug of the alt to keyed power,took blue wire from the junkshun box to the little blade connatore on alt,the dash light comes on when i turn off car and the battry is dead in morneing

When I converted my '84 TD, the original 65 amp alternator had a triple-wire plug with two large red-wire terminals to share the B+ and a single blue wire terminal for the warning-lamp. Instead of plug-ins, the oversize alternator had lug & nut connections. I ran a light-duty battery cable off the 8mm starter B+ to the 6mm B+ alternator lug and a short pigtail adapter to the 4mm warning-lamp lug. Don't recall any keyed-power connection. If I recall, both Bosch alternators DO have an extra blade connection, only used for the radio noise suppressor.

Happy Motoring, Mark

__________________
DrDKW

put the blue wire on the small connector on the alt, leave big wire where you have it.
put NOTHING on the spade connector on the alt... it's for a noise suppressor.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Sounds like it's wired wrong. Why did you connect keyed power to the smaller lug on the alternator? The blue wire goes there!

UPDATE:
Rather than contribute another message to this very long thread, I am submitting the update to the problem described in my original message below.
Solution:
I put the original ("star bolt") tensioner that came with the car back on. Even though it is broken, it solved the problem. I think the "upgraded" (newer style, "L bolt") tensioner I had gotten does not really work on this car. With that one on there, I think the alternator went in crooked. With the original tensioner installed, the problem (see below) is solved. The amp puts out plenty of power, and the belt never squeals. Problem solved. It required no change to the pulley.

ORIGINAL MESSAGE:
Has anyone upgraded to a smaller single pulley or upgraded to a double pulley from a car that had a single pulley?

I have done this 129x upgrade on three cars over the years, and it has always worked pretty well, including upgrading to a 4 gauge wire (and even putting a newer style tensioner in my 1978 240D).
In my current car (the '78 240D), however, I have added electrical components that draw about 51 amps above the stock setup (not all the components are on at all times, but sometimes they all are on together). So, I upgraded from a 55 amp alternator to a 115 amp alternator. That should be enough to handle all my demands, right?
Well, the belt squeals like crazy for minutes at a time no matter how much I tighten it. Even if I tighten it too much, which probably explains why lost a one-week-old belt on the freeway yesterday.
So, I am thinking, my alternator (which I've had for two weeks, purchased rebuilt from a local alternator shop) probably puts out all the current I need, but the pulley just can't handle it.
It has the single V belt pulley, and I wonder if I could upgrade to a double (which at minimum would require deleting my AC compressor, getting a water pump/fan pulley with two grooves if that exists, and discovering a belt that miraculously fits). A simpler solution would be to upgrade to a smaller pulley.
There is some discussion of smaller pulleys in this very thread, but nothing that seems to have been resolved. See posts 77 and 78 here. Post 77 points out that a smaller pulley would have consequences on the life of the alternator, which is unfortunate. Posts 175-178 here talk about upgrading the pulley, but not in a way that seems to apply to my car. Post 194 here describes a successful upgrade to a smaller pulley, but it's a double.
So, I guess my question is this:
Has anyone upgraded to a smaller single pulley or upgraded to a double pulley from a car that had a single pulley?
If so, what are the specs on the pulley and belt?
Were there any other modification required to make it work?
Thanks. I am fully prepared to eliminate some of the components, but it will be sad to discover that my upgraded alternator doesn't accomplish what it is supposed to accomplish.

If you're getting belt squeal, I don't think a smaller pulley is your answer. Yes more RPM's, but also less belt contact area. I would focus on dual belts.

__________________
617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap

Serpentine belt is a better bet, but I don't know of a vehicle you could take it from where it would bolt on.

Maybe someone can tell me what I'm doing wrong...

Bought this: High Amp Mercedes Diesel 240D 300D 1974 1984 Bosch Alternator Generator 120Amp | eBay

Trying to put it on a 85 300TD with double belt pulley. I'm failing to see how this works with the Mercedes 300D though.

I've removed my pulley from the factory alternator and attempted to put it on the alternator I received per the eBay ad.

There's two issues- first the metal fans on the alternator don't seem to line up with anything. There is no 'nub' for lack of better words that keeps the blade in place. So this means the blade needs to be kept stationary by the pulley.

Which is where the second problem comes in, the oem pulley doesn't fit flush onto the blade there is a serious gap. So no matter how tight you put the nut on, it will never touch the blade. So the mounted pulley spins with the alternator and the fan just jiggles around wildly.

Anyone know what gives?

EDIT: Contacted seller, said to use my fan from the stock alternator. I'll go try that... though I think I bent a fin taking the nut off.

DOUBLE EDIT: "Instructions" just said put on old pulley, so I did that literally. However, the gap i noticed was due to the space not being put on after the blade but before the pulley. Once that's on there... all is well. =)

The blue wire is the keyed power wire ~ it supplies a small amount of current from the ground patch of the dashboard lamp to energize the field in the alternator .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I'm finally getting around to doing this myself, but I can't get this sucker to mount. I've tried not installing the top mount until I have the belts on along with the bottom bolt, but then I don't have room to slip the top mount on. If I try to do the same with the top mount on, I can't get the bottom bolt to line up (both attempts with the belts on the alt.).

I may have to get 10mm longer belts, but I am concerned that that will be too long for the adjustment to work.

I have yet to re-clock the alt, rediscovered that need while trying to resolve this problem, but I fail to see how that would affect how it mounts to the engine as that part of the alt does not change.

Can anyone share any wisdom here?

TIA

Never install an alt with the belts on, they go on last! Back off the adjuster all the way for easier belt install (last step).

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked