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Discussion Starter #1
I have an odd engine noise, and it seems that over 3 people have mentioned it could be the alternator bearing that's making a rattling, hollow metallic noise. Here is the thread on the noise:

http://www.mbnz.org/forums/forums/thread-view.asp?tid=1204750&posts=14&fid=10

Does the alternator need to be replaced? All electricals are working great, no dimming of lights or anything. My belts are due for replacement already so I might have the alternator replaced together with the belts.

Lastly, on the alternator it says 55amp by Bosch. Online sources say it's a 65amp one. Is the new (remanufactured) one a better one?
 

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If the alternator has a bad bearing it should be fixed. Eventually it could start on fire. The rattle could also be a bearing in the water pump. Get yourself a mechanics stethescope and probe around. Once you put the probe on the source of the rattle, it will be obvious.
 

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Steven, did you mean to say fix the alternator or replace with a remanufactured one?

Another question: Do you take off the voltage regulator if you return the core to receive your deposit? What needs to be "core"? Just the alternator itself, no voltage regulator, no plugs, no nothing? Thanks

Will get that stethoscope after I grab lunch.
 

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There is a thread talking about higher amp alternators but these cars came with 55 amp. I have replaced my alt with one from Advance Auto. It cost ~$100 and has a lifetime guarantee. Check the alternator before you buy it to see what it comes with because I got one with a pulley and one without the pulley. If you do this then you won't need an extra regulator.
 

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karugs - 3/29/2005 3:45 PM

Steven, did you mean to say fix the alternator or replace with a remanufactured one?

Another question: Do you take off the voltage regulator if you return the core to receive your deposit? What needs to be "core"? Just the alternator itself, no voltage regulator, no plugs, no nothing? Thanks

Will get that stethoscope after I grab lunch.
I did mean to say the alternator can be repaired if you have a repair shop where you live. I, luckily, have a starter and alternator shop about a mile from my house. Alternators with bad bearings are usually repaired for about $35. If you buy a new alternator and you have to return the core, I suggest taking off whatever you can, chances are they won't inspect it to see that it has all components. Also, when alternators are remanufactured, they replace all components, only the hard parts are used.

EDIT: I would be more apt to think the noise is your water pump before the alternator.
 

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1995 E320 Sportline W124
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Stevenpfaff - 3/29/2005 6:04 PM

karugs - 3/29/2005 3:45 PM

Steven, did you mean to say fix the alternator or replace with a remanufactured one?

Another question: Do you take off the voltage regulator if you return the core to receive your deposit? What needs to be "core"? Just the alternator itself, no voltage regulator, no plugs, no nothing? Thanks

Will get that stethoscope after I grab lunch.
I did mean to say the alternator can be repaired if you have a repair shop where you live. I, luckily, have a starter and alternator shop about a mile from my house. Alternators with bad bearings are usually repaired for about $35. If you buy a new alternator and you have to return the core, I suggest taking off whatever you can, chances are they won't inspect it to see that it has all components. Also, when alternators are remanufactured, they replace all components, only the hard parts are used.

EDIT: I would be more apt to think the noise is your water pump before the alternator.

I do have that noise, it's screeching and sounds like a snore at idle. I sprayed WD40 and it's still snoring. My mech said it was the alternator bearing allright, and when we undo it, the coil had been, well, a bit snapped. I bought remanufactured alternator, complete with new IC regulator.

While we at this, I'll ask this question. Is it OK to use 80 amp alternator instead of 55 on ours?
 

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1983 300Dturbodiesel
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extra amps dont make a difference, if there isnt that much current draw the power just isnt used... ill be putting a 115a alt in as soon as i get a weekend with decent weather :>
 

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Discussion Starter #8
Thanks for the responses.

I'm also concerned about the voltage regulator. Would a remanufactured one conditionally have a new voltage regulator installed, along with other necessary stuff? If not then how do I know which parts to remove before returning the core?

MB-owner, I checked at Auto Zone and they don't have the double V-belt type, only the single belt type. So they can't order it for me.

Tiger, did replacing your alternator resolve your problem? It sounds exactly as you describe, only mine is more of a rattling sound and it IS loud when I listened to the alternator via a stethoscope. Checked the water pump and it showed no noise save for the circulating coolant inside and whirring blades.

Steven, I wish I could send it to a remanufacturing shop, but I guess I'll have to do with what I can for now (I have no place to remove it, we're in an apartment and major DIY is a no no here). What about this item?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=33573&item=7965010340&rd=1&ssPageName=WDVW

Pondscum, will the additional amps be used if I have higher wattage items installed, like, say, a sub or an amplifier? And if I don't have extra equipment installed (stock condition like now) the added amps will just speed up the battery charging, correct?

Thanks again. It's either that Ebay item, or one sourced somewhere else together with drivebelts. I am thinking, if I get the cheapest alternator out there, I don't need to bring back the core right? Or am I obliged to? If not then I'll just sell it to a shop who will buy it for more. Possible?
 

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karugs - 3/29/2005 10:46 PM


Tiger, did replacing your alternator resolve your problem? It sounds exactly as you describe, only mine is more of a rattling sound and it IS loud when I listened to the alternator via a stethoscope. Checked the water pump and it showed no noise save for the circulating coolant inside and whirring blades.

Seems we have similar occurence, and yes, the problem is gone once I replace it.[:)]
 

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karugs - 3/29/2005 10:46 PM
we're in an apartment and major DIY is a no no here). What about this item?
Screw 'em! Change it anyway. Besides, I don't see an alternator change as major repair.
 

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I swaped my alternator in 30 minutes.
Remanufactured alternators come with all new parts so don't worry about swaping parts onto a new one.
EDIT: That alternator on Ebay is probably ok, not much of a warranty though.
 

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Anyone know if alts for diesels are wired to charge at lower revs? That ebay item was priced right from what I've looked at. Settled for a $69 55 amp to get back on the road but expect will need 70 amp for night driving in hot weather, ( a/c, fan motor, headlights etc.).
 

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Thanks. I asked the mechanic how much to change alternator AND belts... $50. Cha-ching! Oh well, at least I will save some time. I asked my uncle if we could do the belts before, he backed out. So I'm all alone in the dark. I might go for Autohaus AZ $134 for remanufactured alternator, plus $40 core. Thebenzbin sells theirs for $147 I think, but core is $70! Which is better? I'm confused. I'll purchase it later when I get my mom's car back from the same mechanic (leaky hose problem). Thanks again!!!

Yes that 65 amp alternator will be good enough for increased demands of the electronics. I'm wondering, would a different alternator from a similar engine (say the 300SD W126) work? I could get the alternator from that and it might have more/better output since I still haven't cancelled my plans to upgrade to high wattage lights in the future. How about this?

http://autohausaz.com/catalog/lookup_parts.cfm?SubcategoryID=2412&VehicleID=1195118&CFID=507846&CFToken=40096281

Hmmm...
 

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w126 300sd alternators are the same as the alternators you all have in your cars. 55 and 65amp models. I just went through the whole alternator deal about 2 months ago, and if I learned anything, don't take the cheap way out. First I tried to have my factory alternator rebuilt (well not tried, did), but my problems continued and they tried to tell me it was the battery. So I bought a new battery and the problems continued. So after spending $150 having the alternator rebuilt and installed, with no luck, I realized I needed another alternator. I still have the old alternator, by the way, in case someone wants to buy it to use as a core or something like that. Anyway I lucked out while searching for the infamous Bosch AL129X alternator (115 amp alternator to which everybody is referring). They listed the alternator price at $155.43, but someone ACCIDENTALLY typed in the core charge as $12!!! They tried to make me a deal, but I said noway, because somebody else had the alternator cheaper, with just a higher core charge. Anyway I was probably the first and last person to get that alternator so cheap, but after having it installed, I love it. No starting or charging problems since. (I installed a voltage meter inside the car)
 

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Discussion Starter #15
Lovely! But I already purchased the 65 amp replacement, so I'm off the hook (well until it gets installed). I didn't get the Ebay one though.

Thanks for all your responses. Great wealth of info! I'll update once the alternator has been installed. Right now it's LOUDER! So I'll let the car rest until I get the new item along with the 4 belts. Wish me luck!! [:p]
 
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