Alternator adjusting bolt
 

Anyone know were I can find one of the alternator adjusting bolts with gear teeth on it? It's the 17mm one. It's worn out from the previous owners messing with it.
I have adjusted this thing so many times I never want to do it again.

Thanks

Wrecking yard?

Sixto
87 300D

Try here, click on the buy parts button.

would one be on a 78 240? I have a parts car to pull stuff from....

Very likely your parts car would have it... my 79 240D has the gear teeth alternator bolt. I know that they're also available as an aftermarket part; I inquired at our local shop, MBI, and they had one on the shelf they could sell me for $12.

Kurt

You got a picture of this thing? What year/model of car? I'm not following what you're saying about "gear teeth" on the adjusting bolt.

My 84 300CD has a pivot bolt with a 17mm head, and another bolt through the slotted adjustment bracket with a 17mm head on it. The one through the slotted bracket also has a threaded rod welded to the head that goes to a 13mm adjusting nut that fits into another slot on the bracket - so that adjusting the 13mm nut pulls on the rod to pull bolt and adjust the belt tension. I just did this adjustment yesterday in fact. It was a real PITA, because to even get to it I had to remove the intake snorkel and turbo u-tube.

Sorry guys I keep forgeting to put my car info on my posts as if everyone should just know.

1979 240D... But it's such an early one it might as well be a 78. It's got parts that fit both years on it.

Vstech, I forgot I asked you about that bolt before.
I'm goong to do some checking tommorrow and may get up with you on sending it. Btw what happened to make your 240 a parts car? Rusty? Wrecked?

Thanks

Early models had a gear just under the bolt head.

There should be three 17 mm that need loosened and tightened on the 83-84 timeframe: the lower one lets the alternator pivot, the upper back one lets the bracket pivot and the third closer one adjusts the tension on the belt as the geometry from the other two shifts.

A 17 mm ratcheting box end is good to have. You should be able to get to it just by removing the air-tube to the air filter.

Also, make sure the washers are on the front and back of that bracket. The rear nut on mine was "ground in" to the bracket so much I had to pound the bracket flat and file the burrs and the nut had a wear groove. I saw another one just like that at the junkyard, so I'm guessing a lost rear washer isn't uncommon.

I think some 240's use a similar setup, but the bolt goes rear-to-front and the front-inboard "nut" is actually welded to the bracket.

Note: this is probably NOT what the OP is asking about, but refers to the 90-degree adjuster, not the gear tooth adjuster.

yeah, I got the parts car for the cam... total total rustbucket. the sheetmetal floors are barney rubble style and the seats are mounted to thin air!

Hmmn, As far as I can tell, on mine the "upper back one" is actually the nut for the bolt that goes all the way through the alternator housing and the slotted adjusting bracket. The bolt head on the bracket side has a threaded rod (5mm?) welded 90* perpendicular to the side of the bolt head, and it passes through a fork attached to the end of the slotted adjusting bracket - with a 13mm nut on the threaded rod. Turning the nut against the fork in the bracket pulls the rod - sliding the bolt in the slot of the adjusting bracket to tighten the belt. Kind of counfusing to explain, but as far as I can see there are only 2 of the 17mm bolts. That's all I loosened and I was successful at tightening up the belt.

Yeah a ratcheting 17mm would have helped, and I probably didn't have to take the U-tube off now that I think about it. I took it off to try to get to the front bolt head that has the adjuster rod welded to it from the top. Once I realized that a wrench wouldn't fit on it due to the rod being attached, I ended up loosening the rear nut on that bold from the bottom instead.

And yes I would describe what's on my car "the 90-degree adjuster" vs. the gear tooth adjuster....

On an early 240D I had a while back I found it easier to replace the "adjuster" with a plain bolt and tighten the belt using a bar, stick, fence post, what ever, in back of the alternator:P

Answer
 

1101500372 alternator Clamping Bolt...geared tension adjuster bolt
http://www.peachparts.com/shopforum/mercedes-parts-reference-library/184147-1101500372-alternator-clamping-bolt-geared-tension-adjuster-bolt.html