OM617 balancing

[Blackbolt]

I found a 617 out of the vehicle that the seller claims crazy low miles and he does not realize what a federal engine is do he is selling it for cheap. The only problem is that he does not have the original flywheel. That's a problem right? Aren't these engines internally balanced with the fly wheel? Can I rebalance the engine with a different flywheel and how?

[Stevo]

I dont know but one quick way that might give you a clue would be to look at the crank end for a witness mark that could be aligned with a witness mark on a F/W. If you see such a mark (they are hard to see, use emery cloth and be sure) then I would think a F/W that was balanced with the crank was used. If no mark, you may be home free. I do know allot of 616 F/Ws were balanced independently and had no witness marks on crank or F/W.

[t walgamuth]

Originally Posted by Stevo

I dont know but one quick way that might give you a clue would be to look at the crank end for a witness mark that could be aligned with a witness mark on a F/W. If you see such a mark (they are hard to see, use emery cloth and be sure) then I would think a F/W that was balanced with the crank was used. If no mark, you may be home free. I do know allot of 616 F/Ws were balanced independently and had no witness marks on crank or F/W.

x2

[junqueyardjim]

Do you know why he can't find the flywheel? It is because none of the 617's sold new in NA had a flywheel, though they did have a starter gear attached to the frame that ties the torque convertor to the crank shaft. In any case, I think if you get a 616 flywheel or even a 615, they will work and generally you will have no balance issue. You might have a problem if the engine is a 1985 build model and if you plan to go with a clutch and manual transmission. The 1985 engine crank bore is "about .030 in. too small, but I got mine in by putting it in a deep freeze for a day and quickly tapped it in.

[Blackbolt]

Here is the deal. I am putting a 617 into my Jeep. I am using a Jeep f/w on a custom adapter flange. So if balance is not a big deal I will just make sure the Jeep f/w is independently balanced? The company I am buying the adapter from suggests balancing the Jeep f/w to the original 617 f/w. From what most have posted here it looks like the consensus is that the internal balancing is not life or death? My only concern is keeping vibration down to a minimum and keeping the legendary integrity of a 617.

[Blackbolt]

$500 for a federal 617 with supposedly 70k miles on the tach just seems to good to pass on with or without a f/w.

[t walgamuth]

Here is the deal. The factory service manual says to always balance new and old flywheels together before installing a new flywheel to an engine. From my personal experience and from what many have said here, it would appear that in the 123 MB era that about one in five or so turns out to not be neutrally balanced. For me it turned out to be a 280e crank. All the diesels I have worked with had neutrally balanced flywheels. If it turns out yours is one of those cranks which was balanced together with the flywheel when you put it all together you will have a serious vibration which will require an engine teardown to correct...near as I can tell you its about a 20% chance of a problem....perhaps less.

So, do you feel lucky?

[Stevo]

"So, do you feel lucky? "

Just look for the witness marks, that should tell the story, are they there or not?

[Blackbolt]

The seller lives a 2hr drive away. So I won't be able to look at the engine until I go to pick it up. The witness marks are a good tip. I will be sure to check it out when I go there.

[t walgamuth]

STevo is right, but They are very very faint, or they were on my 280 at least.

I'd take a very good flashlight with me to look at the end of the crank. They resembled holograms on the 280.