Bent balancer?! - PeachParts Mercedes-Benz Forum

mechanicalman · #1 11-08-2008, 12:56 AM

Hey guys, I was driving home down I80 in Richmond, CA tonight and all of a sudden i hear a clunk. I've lost power steering and all the idiot lights come on (battery, brakes, etc.). I pull over and notice all the belts are off the harmonic balancer. It's too dark to tell exactly what happened, but i drive it home with no power steering before it manages to overheat or drain the battery. I get home and take a closer look and notice the balancer is spinning out of true and looks pretty damn bent. I reached down and didn't feel any play in the balancer one way or another.

Where do I start in trying to diagnose this? Bent pulley, ruined crank, i'm a little scared I have to replace the engine alltogether. The belts were pretty worn and i was putting off replacing them, but when this happened, none of them broke, they were just thrown off.

sixto · #2 11-08-2008, 01:01 AM

More likely the rubber material disintegrated so the damper looks deformed. The 616 is pretty tough so replace the damper and be on your way. Maybe throw in a new crank seal.

Sixto
87 300D

mechanicalman · #3 11-08-2008, 01:04 AM

God i hope you're right. This happened at the worst possible time, I'm between jobs and the '65 Corvair that I drive around is on blocks with the engine out.

Any good how-to's on replacing the balancer?

jt20 · #4 11-08-2008, 01:08 AM

http://www.peachparts.com/shopforum/showthread.php?t=235525&highlight=180+degrees

also inspect the 6 small hex cap bolts that hold the crank pulley to the balancer.

jt20 · #5 11-08-2008, 01:11 AM

at the top right of the diesel forum, there is a 'search' option. Many threads about messed up balancers, crank noses, pins etc...

sixto · #6 11-08-2008, 01:17 AM

Bascially you remove the pulley from the balancer, wedge a rod of some sort through a cutout in the balancer and the block, remove the crank bolt, use a puller to extract the balancer. You should mark the pulley to the balancer and the balancer to the crank but if you're replacing these parts, I don't know the benefit of marking. Practice, I guess. Pry off the old seal, put some sealant on the outside of the new seal and oil or break-in grease on the inside. Use a big socket and the crank bolt to press the new seal until it's flush with the timing chain cover. Attach the new balancer and toque to 200-240 lbft.

I say that with every confidence despite never having even checked the oil in a 240D

Sixto
87 300D

jt20 · #7 11-08-2008, 02:17 AM

Quote:

Originally Posted by sixto

More likely the rubber material disintegrated so the damper looks deformed. The 616 is pretty tough so replace the damper and be on your way. Maybe throw in a new crank seal.

Sixto
87 300D

The PO lost his accessory belts.

either the 6 bolts sheared off, or his crank nose is ruined. The damper is only an intermediate b/w the balancer (bolted to crank nose, and fitted pins) and the pulley.

mechanicalman · #8 11-08-2008, 04:27 PM

okay, i went under there and grabbed the pulley with my hand. at first it seemed firm, but after some wiggling the whole thing came loose like it wanted to come off the crankshaft.

does this mean the crank nose is ruined now? i don't quite understand the assembly, or how it's attached to the crankshaft. the haynes manual is pretty unhelpful with this part.

sixto · #9 11-08-2008, 04:55 PM

There are two pieces attached to the crank - the pulley and the balancer. Are both loose or only the pulley?

Sixto
87 300D

mechanicalman · #10 11-08-2008, 05:31 PM

okay, the harmonic balancer is still attached and looks like it's okay. just the pulley is loose, but i can't quite shake it off the end of the shaft.

Verdict?

sixto · #11 11-08-2008, 05:34 PM

IIRC, the pulley is held by 6 bolts that take a 5mm or 6mm hex bit. Maybe some of those bolts backed out or sheared off. See if you can remove what's left.

Sixto
87 300D

mechanicalman · #12 11-11-2008, 04:48 AM

okay, i pulled the radiator out and the it looks like the fan took a hit and broke one of its blades when everything came apart. i got the pulley off the balancer (6mm allen screws) and i could see where 4 of the screws had already sheared off. one of the screws was sheared off below flush with the balancer, so i'll have to use an extraction bit to back it out, the other three i should be able to grab with a pair of locking pliers. the two screws that held were super loose in their holes and i was able to back them out by hand. the balancer is totally fine as far as i can tell. There was some confusion early on because i thought the harmonic balancer and the main pulley were the same part (they are on my corvair).

SO, what do you guys think? should i go ahead and remove the balancer and replace the front shaft seal since i've already got all this stuff off? Should i just get the screws out and re-attach the balancer like nothing was ever wrong? should i tap the thread holes in the harmonic balancer out one side bigger to make sure they hold with the new screws for the pulley?

t walgamuth · #13 11-11-2008, 06:41 AM

If you can avoid taking the balancer off its a good idea, as r and r ing it is tricky and if done incorrectly the nose of the crank can be easily ruined, and that means a tear down of the engine to fix correctly.

Good luck.

mechanicalman · #14 12-03-2008, 06:38 PM

okay, so i took the car to a mechanic that my friend recommended, but i wanted to be there for when the guy r&r'd it to make sure the balancer was put on the same way it came off.

as luck would have it, i was getting a burrito when it came off and only saw him put it on. the guy was vietnamese and a very experienced mechanic, but he didn't do a good job reassuring me that it went back on the same way it came off what with his limited english.

the car seems to be running without any excessive vibrations, but can you guys let me know how i can be sure that it's on right?

Stevo · #15 12-03-2008, 07:23 PM

Can you descried how he put it on, did he set it on the shaft and just draw it on with the center bolt?
At least you got your burrito.