I'm in the middle of removing the alternator from my 82 300SD. How do you remove the adjusting through bolt with bending or damaging the belt tensioning screw? The Haynes manual I have on 123s just says remove the tensioning bolt. The picture they show doesn't look the same.
Thanks for any help

Its tricky but if you slightly been the tab back that houses the actual 13mm threaded nut it will give you just enough distance to get it out. TIP: Cut two to three threads off the end before reassembly. It will make the job just that much easier!! Then next time you won't have to bend the bracket. Also use some antiseize when putting it back together so that it won't rust on you. You will be doing that job again if you keep the car!!

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If it is like a 123 unit, you don't have to bend anything. You simply take the nut off the bolt that goes all the way through the alternator and remove the nut on the tension stud, rotate the bolt so that the tension stud is out of its folded groove, then pull the bolt with tension stud out forward.

Good luck,

I Have found it easier to remove from under the car

I decided to add the tensioning bolt to the SD today. For some reason, it never had the proper bolt with the tensioning stud.

I ran into a problem with the clearance between the alternator and the water pump housing nipple for the heater core.

To release tension on the belts, the alternator pivots upward and toward the engine on a bolt that is almost directly beneath the alternator.

To remove the belts, the alternator needs to rotate about 3/4 of the way along the adjustment slot. However, it cannot do this because it hits the hose that is attached to the aluminum pump housing nipple. So, the belts cannot be removed without removing the alternator.

If the hose is removed from the nipple, then the alternator can move upward just a tad more and the belts can just barely be removed.

Has anyone else encountered this with the SD? It appears that you would have to break into the cooling system and remove that hose to change belts.

Seems ridiculous to me.

The entire situation would be corrected if the belts were 20mm longer.


BTW, anyone who is working out there today needs to have their head examined.

Brian, are you sure you have the correct belts? I had this exact same problem initially but when I got the correct Continental belts, I didn't have the interference with the cooling hose. And I've been avoiding going outside to work, but I may just go out and change the valve cover gasket on my truck. My Mercedes is sitting in the garage, awaiting my next move on it's transmission. I put an air conditioner in then garage window this afternoon, and it's been running for about 4 hours. The temp has dropped about 8 degrees...so far

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Well Pete, it's either the 1000 mm belts or the 1037 mm belts. I don't think the 1037's will work. Just a bit too long. I need about 1020 mm. That would be perfect. But, something is not right. I can't believe M/B would want you to pull a cooling hose to change a belt.

The heat really kicked my ass today. I pulled the downpipe and pulled the water pump, and installed the tensioning bolt for the alternator, and that was about it.

I have done this one several times on my 300SD and on several 123's. I agree with the Benz Tek that you need to bend the tab that keeps the tension bolt in place back just enough to slide that bolt out and finish removing it. I use a screw driver to bend it out then a pair of offset pliers to bend it back on reassembly. It really is not too difficult. The trick on reassembly is to make sure you bend it back enough to clear the path of the belt so it does not rub.

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KCScout
98 S420 My Wife's Baby
97 S320 My road car
83 300D My old road car (love that diesel)
81 300SD Wife's former Baby
81 240D A fun stick shifter
71 220D My first one

Can you comment on the belt installation on the SD? Do you use 1000 mm belts? Can you get the belt on the pulleys without removing the hose directly above the alternator.

After the belt is tensioned, where is the tensioning bolt relative to the slot? Is it all the way to the left (passenger side)??


I've got a strange issue with this one and I can't figure it out.

Brian, I really think I used 1020mm belts. I'll have to go check though. When I got my car, it had belts that did not allow removal from the pulley by slacking adjustment all the way. Now, it works the way it should.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

That's precisely the situation that I am in. 1020 belts would be absolutely perfect. The 1037's for the earlier SD's seem to be too long. My engine number definitely calls for the shorter belts.

Any additional info appreciated.

Brian;

The comments on belt size are right on. Use the 1020mm belt and you will be able to get it over the pulleys with little problem. On the tension nut, there is a notch in the base of the nut that should ride on the cutout in the bracket you removed it from. It is a little trickey getting it back into place as you have to thread it on the tensioning threaded rod then adjust it to just the right length to get to the proper point on the bracket. I am a novice mechanic and have been able to do this several times (I bought some cheap autozone altenators and paid the price in repeated replacements). You can do this.

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KCScout
98 S420 My Wife's Baby
97 S320 My road car
83 300D My old road car (love that diesel)
81 300SD Wife's former Baby
81 240D A fun stick shifter
71 220D My first one

I swapped in an 80 amp alternator to my 300SD, and with 1000mm. belts, I had to remove the alt pulley to place them. ouch!

Bought some 1020 (or were they 1025?) and problem solved.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Thanks for the info.

I think I will find a matched set of the 1020's.

Were they Continentals as well??