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Old 06-26-2007, 12:20 AM
sasquatchgeoff's Avatar
Cascade Foothill Lurker
Join Date: May 2007
Location: Portland, OR
Posts: 561
Looking for Mr. Woodruff Key. 1986 190D 2.5

When changing out my Bosch alternator pulley on my '86 190D 2.5 I committed the gross sin of losing the woodruff key! I did not realize that this was a special woodruff key so I went to several hardware auto parts stores to no avail. My manual's exploded diagram does not denote the size. Any help would be appreciated. Bosch alternator #AL65X.

327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...

Last edited by sasquatchgeoff; 06-26-2007 at 01:14 AM.
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Old 06-26-2007, 02:04 AM
sixto's Avatar
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Time to head for the u-pull-it wrecking yard.

93 300SD 3.0 - comatose
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Old 06-26-2007, 03:18 AM
Cervan's Avatar
Crazy mechanic.
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Location: olympia washington
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aye. this is a Metric woodruff key. measured in Milimeters.
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.
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Old 06-26-2007, 04:29 AM
toomany MBZ's Avatar
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You may be able to talk an ap store (indy) out of one, or anywhere that works on foreign cars.
83 SD

84 CD
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Old 06-26-2007, 07:35 AM
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Marine Engineer (retired)
Join Date: Aug 2006
Location: West Virginia
Posts: 1,268
Arrow MB Dealership....

Your MB Dealership should have them in stock....or can get you one.....or maybe even one of their mechanics will have one in his toolbox......

You may also try a Yamaha Outboard Motor dealership.....Yamaha OB's use some "metric" Woodruff Keys, but I don't know if they have that particular size.....


'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG
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Old 06-26-2007, 10:09 AM
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Go to any hardware store that sells indivisual bolts in trays. They will have a selection of woodruff keys. Sears Hardware carries them
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Old 06-26-2007, 10:16 AM
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Location: Sunnyvale, Texas (DFW)
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For something like this just hit the evil dealer. Can't be that much....
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
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Old 06-26-2007, 03:40 PM
F18 F18 is offline
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From personal experience......get the exact oem replacement. Do not use a "make do" replacement from a hardware store. It has to be an exact fit!
Any play in a Woodruff Key...even microscopic!.....over time it will lead to the pulley breaking loose and hoaning/distroying the alternator shaft. The pulley wheel will bounce around the engine compartment and do other damage before it drops to the pavement and passes you as it squirrels down the road in front of you at high speed.
I had this happen to me in the 84 300SD on the road in Maine years ago (I did not use an OEM woodruff key) Local Maine mechanic had to airfreight in a used alternator with pulley mounted. With the parts, airfreight and the stay in a hotel it was an additional $500 to my expenses. All because I did not use the correct woodruff key!

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

Last edited by F18; 06-26-2007 at 04:00 PM.
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Old 06-26-2007, 06:15 PM
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Are you ready for this?

The reason that I could not find the woodruff key is because it was never there in the first place! (for the life of me I could not remember actually seeing it) I talked to a venerable source who has worked on MB's for thirty years and he said for 1986-on in the 2.5 non-turbo with single belt system, the woodruff key was left out on purpose for if the alternator seized, the torque value was light enough (25-29 ft/lbs) to allow the pulley to spin, make a crapload of noise thereby alerting the driver of a problem but not totally disabling the vehicle. Otherwise the torque was tight enough for normal operation. I am not sure that it made sense but I was willing to torque the pulley on and now I am back to driving my Baby-Benz with no UFO pulleys lifting off out of the wheel well.
327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...
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Old 06-26-2007, 08:16 PM
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I wouldnt worry much about it.Very few automotive alternators have had keys in shaft for the last 20 years or so,tighten the nut properly and it wiil stay.If you are concerned about it put a little Blue loctite on the threads before you put the nut on. My$.02 Don
Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles
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Old 06-26-2007, 10:05 PM
sasquatchgeoff's Avatar
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Posts: 561
Should've looked deeper into my Mitchell guide

I found a tech bulletin in my CD-ROM manual for what it's worth:

TECHNICAL SERVICE BULLETIN ALTERNATOR FAN AND PULLEY INSTALLATION - ALL ENGINES WITH SINGLE BELT DRIVE Model(s): 1984-on Mercedes-Benz 190 D 1985-on Mercedes-Benz 190 E 1986-1987 Mercedes-Benz 300 SDL 1986-on Mercedes-Benz 300 E 1987 Mercedes-Benz 300 D, 300 TD 1987-on Mercedes-Benz 260 E 1988-on Mercedes-Benz 300 CE, 300 SE, 300 SEL, 300 TE Group: 13 - Drive Belts 15 - Engine Electrical System: Charging, Ignition, Preglow, Starter Bulletin No.: MBNA 13/2a, 15/5a Date: March 1988 NOTE: This bulletin supersedes Service Information No. 13/2, 15/5 dated November 1987. SERVICE INFORMATION With the introduction of the poly-V-belt, a woodruff key is no longer used to attach the fan and pulley to the alternator shaft (e.g. alternator, part no. 007 154 54 02). These alternators can be identified by a shorter shaft, on which the keyway is not totally visible (Fig. 1). As of May 1987 production (manufacturer's code 745), the pulley and nut are made of an improved material to lessen the chance of the nut coming loose; and the tightening procedure was changed. In case of customer complaints on earlier production vehicles regarding the pulley/nut coming loose, replace the alternator, pulley and nut. Lubricate the threads and face of the nut with oil and tighten to 70 5 N.m. To tighten the shaft nut, use a 1" drive torque wrench with an 8mm Allen key to fit into the alternator shaft. Use a 22 mm offset box wrench to hold the pulley nut in place. END OF ARTICLE

Like an idiot, I covered the pulley edge w/duct tape and used my pipe wrench to grip the pulley while I applied the torque wrench to the pulley nut. An 8mm socket style allen key along with my 22mm offset box-end would have made the job so much easier.

In spite of everything we know to be wrong, it pays to read the instructions completely
327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...
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Old 08-19-2007, 09:41 PM
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Location: Lincoln Univ. PA
Posts: 48
Lost my belt, but not my woodruff key

My 1986 190d suffered a setback last week when my serpentine belt came off and in the process yanked my waterpump off the block. It appears as if it all started at the alternator, with the pulley seemingly dangling by a thread. I bought a new alt, water pump and water pump housing and went at it. After getting the alternator out of the vehicle and onto the bench, I realized that the pulley had simply come loose, and the woodruff key was missing. Since the alternator seemed to survive the incident just fine, I decided to find a new key and put it all back together. After reading this thread, I now know that the woodruff key wasn't lost since it was never there to begin with. Sasquatchgeoff suggested that such an incident would make a "crapload of noise" and I can't disagree, but it's tough to distinguish a new noise from the crapload that it already makes!
Once again this forum saves me from a wild goose chase!
1998 E300D 1-tank Elsbett Veggie system
1986 190D 2-tank Veggie system -Sold
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Old 03-22-2012, 05:38 PM
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Location: Metro Detroit, Michigan
Posts: 17,359

Over the weekend.

One of my local customers 1986 190D, while driving spun the pulley nut almost off.
This allowed the woodruff key to fall out on the road (gone forever).

The alternator had internal mechanical damage from bad bearings.

The Bosch re-manufactured alternator did NOT come with a woodruff key.

After turning the air blue with creative language...

I was forced to get raw square metric key stock, and hand file a replacement.

As a result, I have ordered four spare woodruff keys that will live in my emergency kit.

Woodruff Key, pulley to alternator
MB# 006888004012
SPECIAL ORDER HBL Woodruff Key,006888004012 - PeachParts

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Old 03-22-2012, 10:43 PM
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Location: coquitlam bc canada
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It appears that they don't use a woodruff key

A Look at the Fastlane listings for Bosch alternators specifies that "No woodruff key is used" . I ran across this when my 87 TD alternator pulley spun off & threw off the belt. I thought the alternator shaft had broken in half until I disassembled it & found the pulley loose, Cheers Dan

It's always something simple
91 300D 603.960 (from japan) 194K
92 Toyota Diesel Landcruiser HDJ81-t 116K
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