W203 Auto, What is correct way to hold crankshaft? - PeachParts Mercedes-Benz Forum

rrf · #1 01-19-2003, 11:54 PM

2002 W203 3.2liter Automatic,

What is the correct way to hold the crankshaft so that crankshaft bolt and the harmonic balancer/pulley can be removed?

I am looking for a different way than the "using the electric starter, while the ignition is disabled" method.

...Is there a proper mechanical hold-down point for the crankshaft?

1991 560 SEC · #2 01-20-2003, 05:48 AM

The correct way, is to use an impact wrench. That way you don`t have to hold the crankshaft.

John

Gilly · #3 01-20-2003, 07:25 AM

The correct way is with a special tool. It has a cylindrical hub with a short rod type extension welded to it, and on the lip of the cylindrical shape are three large lugs. The lugs slip between the "webbing" of the pulley hub, and the one welded on extension remains outside of the pulley (perpendicular to the bolt). A bar can be attached to this extension for counterholding so the bolt can be removed. A socket and extension can be inserted through the center of this hub to access the central bolt.

Gilly

mbdoc · #4 01-20-2003, 08:21 AM

As Gilly said the correct way is with a special tool! The torque on the bolt is 140 ft lbs + 90deg angle of rotation. There isn't any to guage that torque with an impact wrench.

rrf · #5 01-20-2003, 12:24 PM

Do you have the PN for the cylindrical tool?

Thanks everyone!

1991 560 SEC · #6 01-21-2003, 06:10 AM

The question was how to remove the bolt. A torque wrench won`t help removing a bolt.
I do agree that it needs to be held in place and torqued when it is reinstalled.

John

mbdoc · #7 01-21-2003, 08:00 AM

On most MB's using an impact to remove the crank pulley bolt will allow the engine to turn backwards. If this happens many times the timing chain rails will crack. THAT is why you should always counter hold the crankshaft!
The part number for the M112 crank holding tool is 112-589-00-40-00

rrf · #8 01-21-2003, 11:19 AM

Thanks folks,
I was looking for the "textbook" solution, MB Doc had what I needed. Much thx for the PN too. yall are great!.

Gilly · #9 01-21-2003, 08:01 PM

That's the tool number i came up with too.
We had a tech in the shop who counter-held the pulley while trying to remove with an impact (actually several different impacts, the owners of which would "swear" that THEIR impact would remove it, none were successful). These were all 1/2 inch drive impacts. Short of going to a larger impact (3/4 or 1" drive, like a truck mechanic may use) you may not be successful removing with an impact gun anyways. And this was with the engine on a stand, BTW.

Gilly

1991 560 SEC · #10 01-22-2003, 07:10 AM

I stand corrected.

John

Gilly · #11 01-22-2003, 09:57 PM

John:
I would agree that it's worth a shot trying an impact to at least remove the bolt. We may have had an unusually tough one for some reason. Especially if the engine is out of the car. If it's in-car, I don't think there's enough room for an impact wrench, depending on the chassis i guess.

Gilly

Maddog · #12 01-26-2003, 01:46 PM

I just had to do this very recently and I had one hell of a hard time. I first jammed wood into the block so that the crank couldn't turn....no luck there. I finally got it to hold and I actually broke the socket on the breaker bar I was using. Thankgod for craftsman...hehe. Then I took the block to my machine shop guy. We heated up the bolt, and then used his impact wrench. That bolt didn't even think about budging. As a last resort, I stopped by a local axle shop and asked a friend of mine if he would use their bigger impact wrenches to get it off. After about 20 minutes, it finally came off. These guys arn't joking when they say that that bolt is on their tough. I wish you luck!

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