OM617 w/ manual 240d flywheel - PeachParts Mercedes-Benz Forum

MrUkrainian · #1 02-09-2016, 10:04 PM

So I am in a little trouble with my manual conversion. I sourced a manual 1979 240d at a junk yard a while back and got the trans and flywheel and everything I would need for the swap. Then when I removed my auto from my 1984, I also removed the auto flywheel without marking its location to the crank. I looked over the manual flywheel and I have found what I think its the alignment mark to the 240. I am a little confused as to what I should do now. I dont want to mount it as it is because I tried and had bad vibrations, but not 100% sure it was from the flywheel, but now that I have found this mark, it might be. Since my engine is an 84, shouldnt the auto flexplate be neutrally balanced? So could I just have a shop balance out the manual flywheel and bolt it up in any position? I have thought about match balancing the flywheels but then I still would not know which of the 12 positions to bolt it up. Please, someone help, I am stumped.

EJHumber · #2 02-09-2016, 10:10 PM

Best thing to do is pull the motor and have everything balanced to the crank... at this point its honestly just a guessing game. but you have hopefully learned an important lesson, if your not 150% sure if its neutrally balanced, mark everything before you start taking it all to bits.

Mölyapina · #3 02-09-2016, 10:17 PM

Before you tear the engine apart, have the balance on the flywheel checked. With a 1984, there's a pretty good chance it's neutral balance, and in that case, you can have the 240D flywheel neutral-balanced and then mount it in whatever orientation you want.

If it's not neutral-balanced, you might be able to find the markings on the crank and the flywheel. If not, then you might have to pull the motor apart. But no need to jump to that.

vstech · #4 02-09-2016, 11:55 PM

I totally agree... take both parts of the auto flywheel to a machine shop and see if it's got any imbalance.

you might get lucky!

EJHumber · #5 02-10-2016, 12:27 AM

Quote:

Originally Posted by Mölyapina

Before you tear the engine apart, have the balance on the flywheel checked. With a 1984, there's a pretty good chance it's neutral balance, and in that case, you can have the 240D flywheel neutral-balanced and then mount it in whatever orientation you want.

If it's not neutral-balanced, you might be able to find the markings on the crank and the flywheel. If not, then you might have to pull the motor apart. But no need to jump to that.

What makes you think that the flywheel on a 1984 would be neutrally balanced?

Mölyapina · #6 02-10-2016, 12:45 AM

Quote:

Originally Posted by EJHumber

What makes you think that the flywheel on a 1984 would be neutrally balanced?

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.

t walgamuth · #7 02-10-2016, 06:57 AM

i think the 240s are neutral.

Dan Stokes · #8 02-10-2016, 08:35 AM

All I can relate is my personal experience - your mileage may differ, etc.

When I did my conversion with a 240 flywheel I didn't realize until after I pulled everything apart that the engine ('85 OM617) might not be neutral balanced and that (for some reason) M-B did not set up the flywheels with an index so you had to install them properly. (Most American engines w/o neutral balance have 1 bolt hole moved out of the pattern so you MUST align it properly.)

Anyhow, I had no choice at that point other than to bolt the whole deal together and hope for the best. Evidently, everything was neutral balanced and all is fine. I DID have an ace in the hole, though. We often used industrial balancing companies to come on-site and balance our dyno drivelines when we had a vibration issue. I knew that IF I had a vibration I could have the vibration guy come to the shop with his accelerometers and other magic potions and do the ceremony. Usually it runs a couple of hundred US dollars but SO worth it. From that point you can mark your set-up and so if you have to take it apart you can re-align the balance marks.

Dan

charmalu · #9 02-10-2016, 11:35 AM

When I did the 4-spd swap in the 85 300D, I used a 240D FW and had it matched balanced to the auto FW.
The guy said it was off by 10grams as I remember.

So from that, I would assume that all 240D FW`s are not neutral balanced.

To the OP, you could have the manual FW checked against the auto FW to see how close they are or if both are neutral balanced.

Since you do not have the reference point where the auto FW came off the Crank, you now have 12 positions to choose from.

Charlie

C.Doner · #10 02-10-2016, 12:11 PM

My 84 federal OM617 had offset balance corrected by the flywheel. I think offset balancing is inherent to the 5 cylinder engine. It is very difficult to engineer a 5 cylinder engine without external balancing, otherwise every one would have been balanced from the factory.

MrUkrainian · #11 02-10-2016, 05:40 PM

I wont be taking the engine apart because I have just put it back together. The plan was to have everything balanced with the crank but the cost of doing that wasnt worth it in my eyes. If the auto flywheel happens to not be neutrally balanced, I would need to get my manual flywheel match balanced, correct? If i was to get it match balanced, would I be able to tell which position to mount it by trying all the positions? Or is that not possible?

EJHumber · #12 02-10-2016, 10:06 PM

Quote:

Originally Posted by Mölyapina

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.

Mölyapina · #13 02-10-2016, 10:58 PM

Quote:

Originally Posted by EJHumber

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.

I never suggested that he just throw it together, just saying is that he should check the flywheel for neutral balance before tearing down the engine like you were suggesting.

BirthdayBenz · #14 02-11-2016, 07:36 AM

Not sure what your date of manufacture is but on later production engines (like my 85

) MB changed the crank shaft bore diameter from 35mm to 34mm for which no pilot bearing is made. The first thing I'd do is put a caliper in there and make sure you've got a 35mm bore, otherwise you've got a new problem to solve.

Mölyapina · #15 02-11-2016, 08:27 AM

Quote:

Originally Posted by BirthdayBenz

Not sure what your date of manufacture is but on later production engines (like my 85

) MB changed the crank shaft bore diameter from 35mm to 34mm for which no pilot bearing is made. The first thing I'd do is put a caliper in there and make sure you've got a 35mm bore, otherwise you've got a new problem to solve.

That was a 1985-only thing.