Removing Alternator : 300TD - PeachParts Mercedes-Benz Forum

burntcloth · #1 03-06-2011, 06:33 PM

Hi!
I've read threads about removing the alternator from my W123 (1982 300TD), but now, on the job, it's confounding.

My understanding:

From the photo,

Nut #1 has to be loosened (but not removed) to allow belt tension to relax. Bolts #2 & #3 then have to be backed out far enough for the alternator to fall out. The NUT on the fan side of bolt #3 is welded to the adjustment bracket, so all three of these fasteners are loosened from the side in this image (that is, the back of the alternator).

***

My problem: Bolt #3 doesn't turn. I can get a 17mm combo wrench on it, but if it's not turning, should I go get a cheater bar? That's all I can think of. I just want to make sure I need to get that one off.

Then, I can forsee lots of problems backing those two bolts out, particularly given how little space there is. I've heard many folks use ratcheting wrenches on these bolts: is that a straight ratcheting wrench, a stubby, or a flex-ratcheting wrench?

Am I not removing enough? I've taken off the air filter housing and the EGR heat shield, but it's still so crammed in there.

Thanks,
Marshall

ashedd · #2 03-06-2011, 07:10 PM

It's a PITA at best.

From what I remember... someone will correct me if I am wrong.
That bracket needs to come out with the alternator. On my car, and other members, I had to bend something(Adjustment bolt I think) to get the alt out of the car.

I am pretty sure your going to have to get that bolt loose. It is certainly not as straight forward as it looks.

kerry · #3 03-06-2011, 07:14 PM

It's been a while but I think I removed 1 and 2. I may be wrong. 2 I definitely removed from below. I think I broke it free with a socket but may have used a gear wrench to get it out. It tends to not want to come out in my experience.

funola · #4 03-06-2011, 07:33 PM

Loosen the belt tensioner to relieve belt tenion, then Remove the 17 mm bolts/ nuts on the regulator side of the alternator. I used a 1/2" drive ratchet with a 18" pipe for extra leverage. The tensioner bracket stays on the alternator and come out the bottom as an assembly.

Here's a thread with some pics.

http://www.peachparts.com/shopforum/showthread.php?t=285723

vstech · #5 03-06-2011, 07:49 PM

get a can of AereoKROIL or PB Blaster, and soak the opposite side of the bolts with it heavily.
also soak the 13mm adjuster nut before attempting to loosen it and when You do start loosening it, go very slowly back and forth. or you will break it. you've been warned.

your (OP) description is correct. loosen nut, remove 2 and 3 completely. 1/2" ratchet at a minimum is needed sometimes to loosen a stubborn bolt.

toomany MBZ · #6 03-06-2011, 07:58 PM

There is another bracket bolted to the engine block, I had to take off to get the darn thing out.

byronnash · #7 03-06-2011, 08:12 PM

I had to bend the tensioner threaded rod to get it to clear the bracket. Then, to get it back in, I filed a bit of it off so I could fit it back into the bracket. I ended up taking out the fan and shroud to have better access and visibility.

burntcloth · #8 03-06-2011, 08:23 PM

Ok. 1/2 inch drive 17mm socket (maybe with a long breaker) to get that loose. Once it's loose, how do I back the bolt it out, since there's not enough room to keep using the socket wrench.

Yak · #9 03-06-2011, 08:27 PM

Quote:

Originally Posted by burntcloth

Hi!
I've read threads about removing the alternator from my W123 (1982 300TD), but now, on the job, it's confounding.

My understanding:

From the photo,

Nut #1 has to be loosened (but not removed) to allow belt tension to relax. Bolts #2 & #3 then have to be backed out far enough for the alternator to fall out. The NUT on the fan side of bolt #3 is welded to the adjustment bracket, so all three of these fasteners are loosened from the side in this image (that is, the back of the alternator).

***

My problem: Bolt #3 doesn't turn. I can get a 17mm combo wrench on it, but if it's not turning, should I go get a cheater bar? That's all I can think of. I just want to make sure I need to get that one off.

Then, I can forsee lots of problems backing those two bolts out, particularly given how little space there is. I've heard many folks use ratcheting wrenches on these bolts: is that a straight ratcheting wrench, a stubby, or a flex-ratcheting wrench?

Am I not removing enough? I've taken off the air filter housing and the EGR heat shield, but it's still so crammed in there.

Thanks,
Marshall

Go to post 24 in the link funola sent, that will will show what a "welded nut" and plain nut/bolt combo look like. The hole vs. non-hole is not a guarantee.

I've got an '83 300CD with a hole/non-welded nut.

Get some goggles and try working from below.

Pic of alternator mounted, but out of car in #9 here: http://www.peachparts.com/shopforum/showthread.php?t=281707&highlight=alternator

I believe it is possible to remove the alternator without removing #3, but you do have to remove #1 if you're going to try that. And #3 has to at least be loose enough to move the bracket. #2 has to come out regardless. Others may disagree this is possible.

Other pics of odd bolt wear that may jam you up here:

http://www.peachparts.com/shopforum/showthread.php?t=285473&highlight=alternator

kerry · #10 03-06-2011, 08:57 PM

I'm virtually certain I took out 1 and 2. 1 has to come off anyway to move the bracket to a new alternator doesn't it?

charmalu · #11 03-06-2011, 10:26 PM

Every time I do one of these alternators, I have to relearn how to do it, I do it so seldom.

Once all three bolts are loosened, the 13mm adjuster nut can be backed all the way off. (have to do this to remove the belts.) then in theory it can be lifted and the #1 bolt can be removed from the front.

Then bolt #2 can be removed from the rear and the alternator can be lowered and removed from the bottom.

That #2 bolt can be a PITA, as it can be so rusted and corroded, that it won`t slide out. Had that problem back in 07 when I was replacing the engine. luckly I had the eng out, and could just remove the mounting bracket that bolts to the engine.
I could turn the bolt, but it would not come out, even after soaking it in PB Blaster for 2 wks. finally had to beat it out with a smaller diameter bolt.

I would recommend slathering the bolts with Anti-Seiz compound. that #2 bolt catches all the road splash/salt etc.... and really gets seized in.

If that #1 bolt gets screwed up on the adjustment part, here is a fix a guy did a while back that is helpful.

http://www.peachparts.com/shopforum/showthread.php?t=188559

Charlie

burntcloth · #12 03-08-2011, 10:02 PM

Hm. I still can't get bolt #3 loose. I got my 1/2" drive, 17mm socket on it, but there's barely room to get it on without running into stuff in the way:

I've liberally (too liberally, perhaps!) sprayed liquid wrench on the bolts. RED: the problem "#3 bolt." Using the socket wrench gets in trouble with fitting (?) with the blue arrow. Using an open-end straight wrench runs into the EGR clamp (yellow arrow). I can't get that bracket off because the nut on the back is spinning, and even if I could, I don't think it would help. I have a ratcheting wrench, but there's not enough room around that #3 bolt head to get in on.

Any other ideas? Can the alternator be removed without getting #3 loose? It's not obvious to me that #2 can be removed the way it's welded to the adjustment rod which goes through a captive bracket . . .

kerry · #13 03-08-2011, 10:11 PM

#1 has to come out because the new alternator needs to attach to that bracket. As I mentioned earlier, I'm virtually certain I did not remove #3 when I did it. My thought is to back the threaded section out of the adjustment nut and then remove the bolt, but again I don't remember exactly how I did it.

vstech · #14 03-08-2011, 10:13 PM

Quote:

Originally Posted by kerry

#1 has to come out because the new alternator needs to attach to that bracket. As I mentioned earlier, I'm virtually certain I did not remove #3 when I did it. My thought is to back the threaded section out of the adjustment nut and then remove the bolt, but again I don't remember exactly how I did it.

to remove the alt from the bracket in the car, almost requires bending up the bracket.
removing #3 and #2 lets you drop the alt with the bracket still attached. then removal of #1 is easy and no bending is needed...

kerry · #15 03-08-2011, 10:21 PM

Quote:

Originally Posted by vstech

to remove the alt from the bracket in the car, almost requires bending up the bracket.
..

I wish I could remember exactly how I did it but I'm virtually certain I left that bracket on the car when I swapped out the alternator on my 116, and I didn't bend anything.