About a year ago, I installed a gently used Bosch 65 amp alternator in the 1984 300DT. I believe the bearings may be going, however with the sound of the diesel engine running it is hard to tell.

If I disconnect the drive belts and turn the alternator by hand, could I hear any bearing problems? Do bad bearings make a squeal or sound when the alternator is turned by hand?

Use a mechanics stethoscope.... check it when running.. put the probe as close to the bearing as possible .. it will sound rough....

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

OK, will do. I located replacement bearings on rock auto's website. The Bosch 65 AMP alternator drive end bearing is $18.18 and the commuter end bearing is $9.83.

There appears to be plenty of youtube videos showing how to replace bearings on an alternator. I've done so many repairs on this car I believe I could do it. Also, should the stator be replaced at the same time.?

Get the stator and the brush pack and call it good.

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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

FWIW, alternators have slip rings, not commutators.

The bearings on a failing device will sound and feel rough if spun by hand. You can also grab the shaft and give it a wiggle and a tug. If you have ANY play, the bearings are toast.

There is no reason to ever replace the stator unless it has failed. It is nothing more than a coil of wire wrapped on an iron core. There is no "wear" occurring to it. It is either good or bad.

Check the condition of your slip rings when you have it apart, if they're grooved, replace the rotor. Resist the urge to sand the slip rings. If you feel like cleaning them, use Acetone and a clean rag. Nothing else. They should not have any sort of lubrication on them, the graphite in the carbon brushes in the voltage regulator is all the lubrication required.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

You can also use a section of broom stick to listen for where sounds come from. The stick on the Alternator and the other end on your ear.

Watch out for moving parts.

I would worry that you are going to get made in China bearings (which cost about 2-3 dollars on ebay) from rock auto.

If you have the time you can take apart the alternator and the number of the bearing will be on them. Go on ebay and find a source that has USA or Japanese made bearings.

Note when I changed the Bearing on my alternator I found that the Alternator had a sticker saying rebuilt by Bosch North America. Chinese Bearings were inside.

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84 300D, 82 Volvo 244Gl Diesel

It's easy enough to check for play without the belt. The rear bearing is easy to change, the front takes some doing. Make sure you don't damage the retainer plate, it's soft steel.

Well Rock was nice enough to supply the bearing number: NATIONAL 303CC Ball Bearing; Bore=0.6693", Outer Diameter=1.8504", Width=0.5512" Drive end

Apparely Rock Auto does calles it a communtator: Alternator/Commutator end bearing:

NATIONAL 201CC Ball Bearing; Bore=0.4724", Outer Diameter=1.2598", Width=0.3937" 70 amp

NATIONAL 201S Ball Bearing; Bore=0.4724", Outer Diameter=1.2598", Width=0.3937 55 amp

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84 300D, 82 Volvo 244Gl Diesel

They can call it what they want, that doesn't make it right. Slip rings are just that, rings with a continuous contact surface that provide a slip connection (generally in pairs). A commutator is segmented (think of your starter motor). Old cars with a "generator" or "dynamo" had a DC generator and DID have a commutator. An "alternator" is actually an AC device that is rectified to DC through the diode pack in the rear end. AC machines produce an alternating current (hence the name alternator).

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

so...are the rock auto bearings made in china? Also, any idea where to purchase the stator and brush pack?

If they start rattling it's a tell tale sign you're going to replace the alternator in about a week when it exploded. It happened to me.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Don't bother replacing the stator. You're just throwing money away.

The brushes are part of the voltage regulator. Make sure you buy a genuine Bosch regulator. Keep the old one as a spare in the trunk. They're available all over the place, usually for under $40.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Will do. Thank you for the input, now I feel I can go ahead and complete the rebuild.

Anyone know the peach parts number for the voltage regular for a 65 amp Bosch AL-117x alternator?

I just looked at a couple of youtube videos, and I don't like any of the recommendations for pulling the front bearing. They do things like snap the outer race in a vice and use dremel tools to grind the inner race. That's the hard way to do it, and if you slip, you've ruined the shaft. The right way to do it is with a gear puller. There's an illustration on post 10 of this thread (it's a different Bosch alternator, but the architecture of the front bearing is the same):

964 alternator rebuild - Pelican Parts Technical BBS

He removes it correctly. If done this way, the bearing comes out in one piece and the plate isn't mangled.