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Old 02-10-2016, 10:06 PM
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EJHumber EJHumber is offline
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Location: Applegate, CA
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Quote:
Originally Posted by Mölyapina View Post
I've at various points heard a rumour that, around 1982 or so, MB began neutral-balancing all the OM61X engine flywheels.

There certainly are plenty of neutral-balanced flywheels out there, so checking for neutral balance would be my first step -- it's a lot less drastic than pulling the motor.
After having read your post and the others after yours it seems that there are a few individuals that "think" or "have heard" that these flywheels are neutrally balanced. so I got curious and looked it up. Quoting from the factory turbo diesel engine manual (engines 617.95) it says this in group 03 (crankshaft assembly):

03-440:

"the engine is fully balanced, that is, the complete engine has been balanced on a balancing machine. since in the event of repairs this type of balancing cannot be performed, while on the other hand the balanced condition of the engine should be maintained as much as possible, a new flywheel must be brought to the same balancing condition as the removed flywheel."

Just to double check, I also had a look at the NA engine manual ( engines 615, 616, 617.91) and it has this to say in 03-440:

"for engines 615 and 616 the crankshaft, balance plate and flywheel are balanced as one assembly.
In contrast, engine 617 is balanced as a whole, i.e. the entire engine is balanced on a balancing machine (03-450).

since this balancing operation cannot be executed in a repair shop, and as engine balance has to be maintained as well as possible, it is necessary to adjust the balance of a new flywheel to that of the old one. This applies equally well to new flywheels for engines 615 and 616."


The only mention of anything being neutrally balanced is in 03-450 where is says:

"replacement crankshafts are balanced at zero."


but even if this engine we are talking about did have a replacement crankshaft, the balance plate and flywheel still are installed in the same orientation as the old crank (you can find this in 03-450) so just putting the flywheel back on in any place could still affect balance. please know your facts before continuing any rumors of neutrally balanced assemblys in these motors, one of the reasons these motors run like they do is because Mercedes Benz didn't just throw them together and hope for the best, everything they did was well planned and engineered.
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