Harmonic Bamancer story...

[97tbird]

This happened after the car developed a chirping belt noise which I was pretty sure was caused by idler pulley/tensioner/serpentine belt - and a trip to the dealership confirmed it...

well KRAAAAAP !!!

STORY:

so....I went to the dealership to have the new belt, tensioner and pulley installed - and while i am there I remember this OTHER whining noise around 2000 rpm noise that has been bothering me for a while...and thought, well might as well get that checked out - so a tech drives with me, and i reproduce the noise, and he's not tally sure but thinks it might be related to the pulley/belt we're going to replace ... he also thinks it could be the heat shield loose...(which I also thought)

so we drive back to the shop and suddenly we here a THUD !!! and see a pulley rolling down the road - of course we assumed it was the idler pulley finally coming off etc. and get to the dealership safely - drive was about 3 min. AFTER the thing came off...

they go to replace the pulley, belt etc and come back and tell me it was NOT the idler pulley that came off but the CRANKSHAFT DAMPNER PULLEY !!! (this is the same as harmonic balancer, right?)
now they think THAT was that OTHER whiny noise we heard, apart from the chirping Idler pulley.

So, they don't have the Crankshaft Dampner pulley in stock - will get it on Monday..

they also told me that the Carnkshaft d. pulley is actually a double pulley that's sandwiched betw. some rubber surround and that dry rotting of the rubber may have damaged it...and THAT in turn probably made the idler pulley go bad.

ANNOYING !!!

I hope the Crankshaft D. Pulley (Harmonic balancer) being bad for some time didn't cause any damage to the crankshaft/engine... That other "whiny" noise had been around for about an year...
according to this, the harmonic balancer going bad CAN cause damage to crankshaft..

http://en.wikipedia.org/wiki/Harmonic_balancer


Quote:
...Over time, the energy dissipating (rubber/clutch/fluid) element (of the harmonic balancer) can deteriorate from age, heat, cold, or exposure to oil or chemicals. Unless rebuilt or replaced, this can cause the crankshaft to develop cracks, resulting in crankshaft failure....

 

[willix]

I'v seen crank cancer several times and its usually terminal for the moter unless the crank is replaced. I had to stick a fork in a 5.0 Ford they brought me that completely wore the keyway out & 1/4" or more off the crank snout. It ran perfect but unfeasible to repair.

 

[mc2lizard]

Tbird.. with the 4.6? I had one.. great car. you're probably ok unless you noticed excessive vibration.. and the 4.6 motors are absolute tanks. If youre really paranoid send out for a uoa and cut open your oil filter and run a magnet across it. their crankshafts are nodular iron (and way overbuilt for stock- stock cranks can easily handle 350 - 400 whp) so it will def .be picked up by a magnet if there are any sizeable shards.. but like i said most likley youre fine as long as you dont notice any knocking or excessive vibration once its fixed... Don't bother trying to drop the pan to check clearances on the crank, the k member obstructs everything.. can't pull the pan without pulling the motor

... and you have to wait till monday??? what [censored].. i can pick a harmonic balancer up for that engine at any local napa..

 

[mechtech2]

It depends on the engine.
On some cars, there are crank dampeners for the serpentine belt and accessories. They appear to be regular crank dampeners/harmonic balancers, but are only there to attenuate outside vibrations.
Some real crank balancers are counterweighted to help balance the crank/pistons, and/or are tuned by mass and rubber dampening.

 

[97tbird]

Yes it's a 4.6L

I have not been feeling any unusual vibrations, except for the vibrating (whining) NOISE (can NOT FEEL anything during noise) around 2000 rpm for the last 8-9 months or so. Car ran fine without any abnormal symptoms, so I hope no damage was done...but I did have the car driving a lot at that rpm, which is exactly 70 mph)

Will report back after they replace the whole lot. (the H. Balancer, idler pulley, belt, tensioner)

if It DID damage the crankshaft, which symptoms should I watch out for?

 

[d00df00d]

A torsional damper is not the same thing as a harmonic balancer. That Wikipedia article is bunk, and so is is the definition it links.


A torsional damper helps absorb torsional vibration from the crankshaft and isolate the crankshaft from the vibration of the accessories. It will have some kind of elastic component, usually a ring of rubber, for this purpose. If it wears out, crankshaft damage might occur but would probably take a LONG time to pan out. If it breaks, your accessories will stop working and that's about it.

A harmonic balancer compensates for unbalanced internals. It will have a counterweight for this purpose. If the counterweight somehow breaks off, then the engine will start vibrating a lot more and crankshaft failure might result.

A "dampener," presumably, is something that makes things wet. Not really applicable to pulleys.

Quick terminology review: Counterweights balance. Rubber damps. Water dampens.


- Rubber/fluid with no counterweight = Damper. Failure is not catastrophic.
- Counterweight with no rubber/fluid = Balancer. Failure is catastrophic.
- Both rubber/fluid and counterweight = Damper & Balancer. Failure may or may not be catastrophic.
- No rubber, no counterweight = Just a pulley. Failure... would be interesting to see.
- Fire hose = Dampener. Failure means the house burns down.

 

[97tbird]

Thanks
so does anyone know which type the 4.6L has?

I know it has rubber - but not sure about fluid or counterweight.

 

[mc2lizard]

4.6l is internally balanced iirc (may be wrong.. percoset does funny things to my memory.. thank you broken rib) the "harmonic balancer" is just a vibration damper all about the NVH levels and longevity of the accesories it drives - has no substantial effect on the engine.. like i said the engine is a tank. i wouldnt worry if i were you.

 

[97tbird]

Thanks to all you guys - I just spoke to the SA again, and he confirmed what you guys said, incl. mc2lizard (sorry about the rib). He said it shouldn't have damaged anything, and that in this engine it's for external NVH enhancement.

 

[rclint]

A "dampener," presumably, is something that makes things wet. Not really applicable to pulleys.


doodfod a dampener can also be used as word for dampen a vibration.

1. To make damp.
2. To deaden, restrain, or depress: "trade moves . . . aimed at dampening protectionist pressures in Congress" (Christian Science Monitor).
3. To soundproof.

5. dampen - make vague or obscure or make (an image) less visible; "muffle the message"
deaden, damp
soften, damp, weaken, dampen, break - lessen in force or effect; "soften a shock"; "break a fall"
6. dampen - check; keep in check (a fire)

dampen [ˈdæmpən]
vb
1. to make or become damp
2. (tr) to stifle; deaden
dampener n

 

[rclint]

I doubt you have done any harm at all to your engine, however it is good that you have it fixed. I have seen several of these come off, GM 3800 are notorious for this very thing, and I have seen them go another 200k after the problem... and it actually had another harmonic balancer/dampener go bad again before the 200k was over

 

[racecougar]

That failure isn't particularly common on the 4.6L MN12's. Did the pulley seperate from the hub, or did the entire assembly come off the crank, breaking the bolt? The SC 3.8's see this failure much more often.

-Rod

 

[97tbird]

i am not 100% sure - but the way they described it and from what I could see, it separated from the hub - Bolt did not break - they said it's a simple job to replace the pulley.

 

[Shannow]

Doodfood, a torsional damper is supposed to damp down the natural harmonic torsional vibration of the engine.

A lot of diesels down here have a dual mass flywheel at the other end as well.

I've seen torsional dampers fail and kill an engine (typically V-8), and engines fail, killing the torsional damper (Holden 6s with #2 or #5 on the way out)

 

[javacontour]

My Geo Prizm has a similar setup. In my case, the pulley was walking off as the rubber had let go. Belts were "flipping over".

I think the failed A/C clutch took it out. So I replaced it in 2005 at 171K miles and the car is still running today at 253K

I know they are different engines, but I wouldn't worry too much since you are getting it replaced.

 

[willix]

crank cancer subaru Crank cancer SHO