Proper vibration damper installation

[structured]

So my car is misfiring really badly. After my mechanic changed my plugs and wires, and I replaced the cap and rotor, I have found what I think is the true source of my problem. I can move (rattle) my vibration damper by hand and I think that it is hitting the water pump pulley (there is a loud metal on metal tapping sound that is rpm dependent). Hitting the water pump pulley isn't the problem, but I think that the crank position sensor isn't reading the gear properly due to the excessive movement.

What I need to know is how to inspect the vibration damper and how to reinstall it properly. I loosened and re-torqued the six 13mm hex bolts that hold the dual belt drive pulley thingy with the thought that it would also clamp down on the damper, but I could still move it by hand.

Any help would be great.

Edit: Just want to clarify that the vibration damper is able to rattle back and forth (not in a circular motion) while the drive pulley in front of it is fixed and not moving at all.

[!kid]

the dampner i belive can only go on one way are you sure its on right? i cant remember to well but i think there is a small hole on the dampner and a little dowel on the crank snout and the two need to line up dubble check that if your not 100% sure.

hope that helps

[jlevie]

The harmonic balancer is a two part assembly with the toothed ring bonded to the hub with rubber. If you can move the toothed ring relative to the hub I'd say that the bond has failed. The only fix for that is to replace the harmonic balancer.

[structured]

The harmonic balancer is a two part assembly with the toothed ring bonded to the hub with rubber. If you can move the toothed ring relative to the hub I'd say that the bond has failed. The only fix for that is to replace the harmonic balancer.

This is what I was looking for. I guess I'll see what it looks like when I remove it. Unforunately, I just looked up the part and it is like $375 from bavauto. Anybody have one in decent shape?

[structured]

another question:

is there a difference between the vibration damper for early cars and later cars? mine is an '87.

[jlevie]

As far as I know, the harmonic balance is the same on all M20B25 engines, from 9/86 on. You could check realoem to see if the part number changed.

[Ruffian]

The harmonic balancer is a two part assembly with the toothed ring bonded to the hub with rubber. If you can move the toothed ring relative to the hub I'd say that the bond has failed. The only fix for that is to replace the harmonic balancer.

? I'm confused by this Jim. Is there a rubber bonding between the ring and the mount points? I always thought it was one piece of metal.

On all the m20's i've seen, the two pieces are the toothed ring which has a single alternator belt pulley channel and the two belt (air conditioning and power steering) pulley and those aren't bonded at all. I think what has happened in the case of the OP is that the larger toothed ring hasn't been seated properly on the positioning stud as !kid pointed to. With this ring off axis, that's probably your metal grinding as it slides along the timing covers, then off the covers and back against the cover.

Just re-torque-ing the bolts won't fix this issue. You'll have to remove all 6 bolts, remove the two belt pulley, the correctly line up the outer ring with the stud in the small extra hole. Then replace the smaller pulley and you should be good to go. Depending on the wear on your outer ring, you might want to think of replacing it as balance integrity may be off-kilter.

[structured]

^ I believe that Jim is saying that the inner piece itself (the damper) is a two piece assembly. Specifically that the hub and gear are bonded together with some type of rubber seal. You are still correct in thinking that the outer piece (the two-pulley part) is separate.

Like I said before, after tightening the six hex bolts, the damper should not be able to move in and out perpendicular to its direction of rotation. In my case, I was able to rattle the damper toward the block and then towards the radiator by hand even when the six bolts were properly torqued. The problem isn't that the damper is out of alignment, like you said, it's that it is shaking back and forth freely.

Does that make sense?

[structured]

So this is what I'm working with:

The vibration damper...


...and after the toothed ring fell off, revealing the rubber surface on the hub...


^is that supposed to happen?

Do I need to remove the crankshaft bolt in order to remove the hub?

[nando]

you need a new crank wheel! looks like it was pretty rusty.

no, you don't have to remove that bolt. just tap on it with a hammer, it should fall off eventually.

[bimmer630]

if he can just tap that wheel off the crank, then whats holding it on there? the crank face is right there and the only thing that bolts to that is the drive belt pulleys.... it looks like the crank bolt holds both the dampner and crank flange as a unit. ive never actually taken apart an m20 im just looking at the pic and wondering

[Jargo]

if he can just tap that wheel off the crank, then whats holding it on there? the crank face is right there and the only thing that bolts to that is the drive belt pulleys.... it looks like the crank bolt holds both the dampner and crank flange as a unit. ive never actually taken apart an m20 im just looking at the pic and wondering

The bolts go through the drive belt pulleys, through the vibration dampner, and into the crank flange, holding everything on tight. The reason Nando said he could just tap the dampner off is because the pulleys and bolts were already removed!

[structured]

To give you a better idea, this it what the toothed portion looked like after it was removed:


Notice that there is no way to secure this to the flange shown in the previous picture. The only thing that was holding it on was friction caused by the drive pulleys when they were attached. I find it hard to believe that this is correct.

So, can anybody confirm that the toothed gear and the flange shown in the second pic(9th post) are supposed to be one piece?

[nando]

yes they are one peice, they are (supposed to be) bonded together.

I've seen them come apart before (usually on really rusty cars). I don't think you'll be able to bond them together safely, and it's critical to the timing of the car anyway so it wouldn't be worth messing with.

and yes, the pulleys are what holds the damper/toothed wheel on the crank, not the crank bolt.

[Jean]

That sucks dude! Good thing is you can pick one up for probably under $50 from a parts car.