harmonic balancer 103 out of round - PeachParts Mercedes-Benz Forum

lee polowczuk · #1 03-12-2011, 02:33 PM

I can see that the rubber harmonic balancer is out of round.

I believe this caused stress on my fan bearing bracket..

I can't seem to find any info on removing the harmonic balancer or getting a new part.

Clearly this is the cause of an idle problem similar to motor mounts being shot... i have newer mounts and you can see the rubber harmonic balancer is out of round.

any help would be appreciated. can't seem to find it on the forums or in the factory service manual

JohnM. · #2 03-12-2011, 02:47 PM

I'm trying to picture what piece your talking about in the fan clutch area but I can't. Where is this rubber harmonic balancer?

lee polowczuk · #3 03-12-2011, 03:14 PM

Quote:

Originally Posted by JohnM.

I'm trying to picture what piece your talking about in the fan clutch area but I can't. Where is this rubber harmonic balancer?

it's directly behind the crankshaft pulley..... almost looks like a flex disc

JohnM. · #4 03-12-2011, 03:28 PM

I know what your talking about now.That's a really uncommon failure. I wonder if road debris damaged it or something? It appears to be a special order part. Allparts Express and Fastlane don't have it listed in their online catalog, nor do any of my normal parts suppliers. So either special order or a good used one.....

I would imagine the crank pulley has to come off to R&R the harmonic balancer. Maybe the harmonic balancer is part of the crank pulley? Not sure.

lee polowczuk · #5 03-12-2011, 04:50 PM

i think in some instances it is part of the crank pulley.

i am being told it could be a dealer only item...

it's so uncommon, you can't find much on the search about it.

but, here is what happened...or at least i think what happened..... somehow it went out of round...and it started wearing the camshaft position sensor ( a part mbdoc says does nothing).... i noticed that it was shaving the bottom of the sensor off....into shredded pieces of copper.... at the same time it seemed like my fan bearing bracket was going....

so i replaced the bracket...and a few other things while i was deep into it...

....when i went to put it back together.... still the engine vibration and some rubbing of the fan pulley against the camshaft pulley...

well the the camshaft pulley has a slight wobble to it because the harmonic balancer (rubber) is out of round.

don't know what caused what....but i am not driving the car until i get a good piece of rubber.

i also replaced my upper timing gasket and camshaft gasket , valve cover gasket, and distributor cap and rotor while i was in there.... I am fairly sure they were all original..... 22 years old and 109k miles.

it's a good learning process.

JohnM. · #6 03-12-2011, 05:01 PM

Very interesting! An out of round crankshaft pulley assembly would definitely wreak havoc on the rest of the belt system and the fan bearing bracket / idler pulley is weakest link.

lee polowczuk · #7 03-12-2011, 05:13 PM

Quote:

Originally Posted by JohnM.

Very interesting! An out of round crankshaft pulley assembly would definitely wreak havoc on the rest of the belt system and the fan bearing bracket / idler pulley is weakest link.

other than the harmonic balancer...my concern is something to counter the pulley since it will turn when i try to break the bolt.....

there's no little slot to stick a 1/4'' rod in, like the fan pulley...

JohnM. · #8 03-12-2011, 05:19 PM

Quote:

Originally Posted by lee polowczuk

other than the harmonic balancer...my concern is something to counter the pulley since it will turn when i try to break the bolt.....

there's no little slot to stick a 1/4'' rod in, like the fan pulley...

I just looked at a picture of an M103 crank pulley and it appears there are 6 allen head bolts that hold it on. It takes a bit of strength to turn over the engine by hand with the belt on, etc. I don't think you will have a problem with the crank pulley turning while you break loose those bolts.

duxthe1 · #9 03-13-2011, 08:31 PM

The setup has a hub bolted to the crankshaft with a large very tight bolt. The "damper" sits on the hub and then the pulley sits over it with the six allen bolts holding both to the hub. I dont see any way that the damper would fail and end up out of round. I'm suspicious that the large bolt that holds the hub has worked loose and the whole shebang is wobbling and likely damaging the crankshaft at the same time. FWIW if you have to remove that large bolt for the hub you hold the engine at the flywheel. There is a special tool for the job but you can get by without it. Just be warned that large bolt should be tightened to 250ft/lbs + 90 degrees....=really friggen tight.

lee polowczuk · #10 03-13-2011, 10:21 PM

Quote:

Originally Posted by duxthe1

The setup has a hub bolted to the crankshaft with a large very tight bolt. The "damper" sits on the hub and then the pulley sits over it with the six allen bolts holding both to the hub. I dont see any way that the damper would fail and end up out of round. I'm suspicious that the large bolt that holds the hub has worked loose and the whole shebang is wobbling and likely damaging the crankshaft at the same time. FWIW if you have to remove that large bolt for the hub you hold the engine at the flywheel. There is a special tool for the job but you can get by without it. Just be warned that large bolt should be tightened to 250ft/lbs + 90 degrees....=really friggen tight.

Thanks, so much for your reply. It was difficult for me to assess this correctly, but see if you can follow me.

I took off the six allen bolts... took off the pulley.

The big bolt is tight. However, a metal plate separated from the other (i guess damper plate) plate. I might need a puller to get the other plate off...or else i need some wd-40 or some-such.

I think the separation of the plates caused some sort of wobble. I don't think the crankshaft is damaged.

I can purchase the part that will secure the flywheel...but don't really think I need it... I just have to get the damper plate off.

I am trying to secure another harmonic balancer damper. I don't understand the design. Why would one plate be bonded to another in some manner.... seems like a metal disc is bonded to a rubber coated metal plate to form the harmonic balancer.

See if this makes sense. A colleague told me his plates separated on his car, causing the same symptoms.

I'll keep everyone posted. Everyone says this failure is uncommon.

cypress · #11 03-13-2011, 11:02 PM

Take a look at this thread...

Vibration Damper/Harmonic Balancer

lee polowczuk · #12 03-13-2011, 11:08 PM

Quote:

Originally Posted by cypress

Take a look at this thread...

Vibration Damper/Harmonic Balancer

i had seen this thread..... the 103 harmonic balancer is a different set up..... but thanks anyway...

i saw a 103 with a set up at the boneyard today..

i am sourcing the part tomorrow.

lee polowczuk · #13 03-14-2011, 03:14 PM

Ordered a used harmonic balancer today for 65 dollars shipped. I will see how this goes.

In the next couple of weeks, I will probably get another from the boneyard to have as a spare.

We've had other 124's and never had this problem . Our highest mileage one had 226k on it.....

lee polowczuk · #14 03-18-2011, 05:13 PM

Just a follow up.... I got my 65 dollar part and installed it.

The two harmonic plates separated as said in a previous post.

Other than an out an out failure of the part, oil dripping from a leaking upper timing cover may have contributed to the separation of the rubber.

I had a fan bearing bracket, so I installed that. Got a new water pump since I was already in there (will keep the old one for a spare). Did the timing cover gasket and cam gasket. Also did the distributor cap and rotor.

All of these parts were 22 years old.

By the way, the vibration of the engine also loosened spark plug one.... tightened it.

JohnM. · #15 03-19-2011, 01:41 AM

Good to hear! I wouldn't doubt that the oil dripping onto the balancer played some role in its early demise.