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Broken harmonic balancer

Started by Casey, 19 October 2011, 08:41 PM

Casey

Quote from: 1980sdga on 21 October 2011, 04:47 PM
I think it has been recommended that the cup washers (16) be replaced with new ones. Probably wouldn't hurt.

Well, I've got 3 from the junk yard - 1 from the 300SD and 2 from the 240D.  Strange neither had 3.  In any case I ordered the pins and will try an easy fix.  If that gets it working again then I'll likely order new washers for the long-term.  They're kinda pricey for washers - about $8 each.  But that's not bad in the grand scheme of things.

I think I'll be buying a bigger torque wrench (mine only goes to 150 ft. lbs) and checking that these bolts are tightened to the proper amount on all my cars as routine maintenance.

1980sdga

Quote from: koan on 20 October 2011, 06:11 AM
To prevent the engine from rotating when dealing with the hub nut I made up a metal plate with about a meter of angle iron attached. The plate has a large central hole to clear the hub washers and bolt head (m100), and six (or eight?) holes round the large hole that match the pulley holes.

Bolt it up where the pulley mounts, may need spacers, the end of the angle iron sits on the ground. With 4 feet of water pipe on a 3/4' drive socket the nut is easily removed or tightened. The required 400 nm torque is 75 lbs pull at 4 feet, just guess.

koan

...

Gerard

#47
Quote from: 1980sdga on 22 October 2011, 01:03 AM
Quote from: koan on 20 October 2011, 06:11 AM
To prevent the engine from rotating when dealing with the hub nut I made up a metal plate with about a meter of angle iron attached. The plate has a large central hole to clear the hub washers and bolt head (m100), and six (or eight?) holes round the large hole that match the pulley holes.

Bolt it up where the pulley mounts, may need spacers, the end of the angle iron sits on the ground. With 4 feet of water pipe on a 3/4' drive socket the nut is easily removed or tightened. The required 400 nm torque is 75 lbs pull at 4 feet, just guess.

koan

...

Raptelan

I removed the crank pulley on an M103 engine.  Cant remember the book figures for the torgue, but I made up a bar (probably not a million miles off what Koan did) drilled a few holes in it, and used a few long bolts to grab onto the crank pulley threads to prevent the crank from turning.  Some grinding and shaping was necessary.  This tool then reacted off the chassis rail, or the ground, I cant remember.
I then used a breaker bar and extension pipes to open the bolt, the torque was bastardNm or (Christ sakes ft/lbs).

Replacing involve re using the home made tool and tightening the other direction again to bastard Nm, or (Christ sakes lbs/ft).  I know the situation is not the same on yours but you might get some ideas.

Internet pic


EDIT
an internet search found this tool, similar to what Koan and I did,


1980sdga

I think this is a better method than using the flywheel. 

Casey

Just in case anybody references this thread later, I found this:

http://mercedessource.com/node/9379

koan

Quote from: Raptelan on 14 December 2011, 10:00 AM
Just in case anybody references this thread later, I found this:
http://mercedessource.com/node/9379

That's one of the off the shelf buy anywhere pullers, I paid about that price in AUS from Repco. Pulled M100 front pulley off with it.

koan
Boogity, Boogity, Boogity, Amen!

Casey

So I finally got around to trying to fix this (yes, I know), and found that the pins won't fit into the harmonic balancer anymore, as the edges of the grooves have been bent in.  Okay, I can get another balancer...

Bigger problem is that I examined the grooves on the shaft coming out of the engine, and what should be clean semicircles are stretched into long semiovals. :(

So I guess I must replace the whole shaft thing?  What's that called and what's involved to do it?  Or will it work to just fill in the extra space with JB weld and not bother with replacing the shaft?  I know that's not a job done well but might it hold up for a good while that way?

TJ 450

#52
Unless you feel like getting adventurous and taring down the engine to remove the crankshaft, the oval keyways will have to suffice... Are they oval the whole length? If not you could easily get away with reassembling with a replacement balancer, but make sure that bolt is torqued to spec. 8)

Not ideal, but not the end of the World either.

Tim

P.S. Try and use the old one if you can, a replacement might not be effective and damage the engine through resonance in the long run. They are balanced with the flywheel and crankshaft etc. at the factory as mentioned before.
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Casey

Quote from: TJ 450 on 08 March 2012, 12:04 PM
Unless you feel like getting adventurous and taring down the engine to remove the crankshaft, the oval keyways will have to suffice... Are they oval the whole length? If not you could easily get away with reassembling with a replacement balancer, but make sure that bolt is torqued to spec. 8)

They are nearly twice as long as they should be.  It looks to be surprisingly uniform wear.  My guess is that the big bolt must have been loose for quite some time before it finally fell out, and the little pins did not come out right away but rattled around for some time.  It would seem the harmonic balancer semicircles ended up pinched by the pins ending up stuck behind it once the bolt loosened enough for the harmonic balancer to come out a little bit.  I can try to get a picture but I have to use a mirror to see them at all since I didn't want to pull the radiator and A/C fan out.

I reckon I'm willing to rebuild the engine as far as necessary to replace the crankshaft, but I have no idea how to do all that.  I'm guessing the engine would need to be pulled out?  It seems worth doing as it only has 80k on it, any ideas how much a reasonable shop would charge me to do the job properly? (I guess too much to be worthwhile?)

QuoteP.S. Try and use the old one if you can, a replacement might not be effective and damage the engine through resonance in the long run. They are balanced with the flywheel and crankshaft etc. at the factory as mentioned before.
Is it safe to use a file to make the holes big enough for the pins to fit in them?  Because they don't now...