Reply
Thread Tools Display Modes
#1
Old 06-29-2004, 11:16 PM
Registered User
Join Date: Mar 2004
Location: On the level, if inclined
Posts: 13,233
How Did I Break My Harmonic Balancer?

Not 60 minutes ago, if someone told me my engine was making that nasty knocking sound because I'd blown my "harmonic balancer" I would have looked at them sideways and asked, "Are you sure it's not the oscelation overthruster?" Because folks, who on God's green earth calls anything a "harmonic balancer?" Sounds kinda redundant if you ask me, but tomorrow I'm gonna have to get on the phone with some scrap yard guys and ask them, "I say there, stout yeoman, have you an harmonic balancer for a 1983 Toyota Corolla? For mine seems to have damaged itself rather badly, yes?"

Now, this whole deal would be going down in The Pit right now if it weren't for 2 things: 1) removal and installation of this part on this car takes all of 10 minutes and 2) my need of a factual answer to the following question is outweighing my desire to bitch about my car.

For those of you who do not know what an Harmonic Balancer is, it is a pair of pulleys at the front of your engine that powers those damned belts that are always breaking. These pulleys NEVER need to be separated one from the other during the course of normal (or other) operation of a motor vehicle. So why they are separated at all, and why they are joined by a thick plastic washer (they kind of telescope together and the plastic bit creates a frictiony, pressure adhesion between the two parts) I will never know.

For those of you who DO know what an Harmonic Balancer is, how/why do they fail? A month ago I had occasion to remove mine when my timing belt broke (hooray for non-interference engines!) and I figured I had re-installed it correctly--it's pretty hard to screw it up, it only goes on one way! Did I get my fan belt too tight? The only things that belt operates are the fan, water pump and the alternator. Where did I go wrong?

For those of you who do not know what an Oscelation Overthruster is, well, watch your Buckaroo Banzai.
#2
Old 06-29-2004, 11:58 PM
Charter Member
Join Date: Aug 1999
Posts: 16,451
Inigo don't sweat the oscelation overthruster, the ones on Corollas never go bad. I would watch out for the bypass hose to the knunten valve, now those are prone to failure.
Seriously the harmonic balancer is designed to kill vibrations from the engine itself. The fact that you can put grooves in it to run fanbelts is just a plus.
Balancer do fail, either by falling apart or on the ones that are two metal rings (inner and outer) having the rubber bonded between them fail.
Is there any chance that when you reassembled the engine you did not get the balancer (crank) bolt tight enough? Some times those crank bolts have a torque spec of as tight as it can go, plus 1/2 turn. RTFM
You did not specify just how your balancer failed, but if it was located on the crank by a woodruf key, the key may now be destroyed (ask me how I know this) If you are unfamilar with the name, a woodruf key is a small piece of metal that is semicircular on one side and flat on the other. It fits into a machined recess in the crank sticking slightly above the surface of the crank to locate the pullys. When installed the key looks like a long skinny rectangle off of the surface of the carnk. A hammer and a punch will remove the damaged one, and a hammer will tap the new one into place.
If the old key is destroyed, and you cannot get one the exact size, it is possible to grind/file one that is slightly oversized and make it work (again ask me how I know this)
#3
Old 06-30-2004, 12:54 AM
Member
Join Date: Mar 2002
Location: KCMO
Posts: 11,121
Harmonic balancer = vibration dampener = front crankshaft pulley.*

Harmonic balancer is not redundant, as there are any number of things that can be balanced where harmonics are not involved. Essentially, it dampens harmonic vibrations inherent in the rotating mass of the crankshaft by acting as a counterbalance, hence the names above.

It is not a pair of pulleys. It is a single pulley made of three pieces: an inner metal hub, an outer metal pulley ring, and a rubber (not plastic) ring between the two. It is not held together by friction and pressure, but by the rubber being bonded to the metal, just as rubber is bonded to metal in motor mounts and suspension bushings. The typical way they fail is the bond gives way, allowing the outer ring to rotate independently of the inner hub. If this is how yours failed, it's not related to the work you did, just the result of age and use.


*True for this engine. On some engines the balancer does not have an integral pulley, and all the pulleys are bolted onto the balancer. On other engines the crankshaft is internally balanced, and there is no balancer, with the front crank pulley being a solid hunk of metal.
#4
Old 06-30-2004, 01:39 AM
Charter Member
Join Date: Mar 1999
Location: Anderson, IN,USA
Posts: 14,584
I have deleted a long explanation. It was boring and detailed, and no one cared about it more than me. I had already read it, though, so why bother?
#5
Old 06-30-2004, 08:10 AM
Registered User
Join Date: Mar 2004
Location: On the level, if inclined
Posts: 13,233
Quote:
Originally Posted by Rick
Is there any chance that when you reassembled the engine you did not get the balancer (crank) bolt tight enough? Some times those crank bolts have a torque spec of as tight as it can go, plus 1/2 turn. RTFM
You did not specify just how your balancer failed, but if it was located on the crank by a woodruf key, the key may now be destroyed
Luky me, the key is OK. I got that sucker on pretty tight, but I don't often work on the engine itself--peripheral junk all the time, but I leave the crank & innards alone. I'm kind of afraid of twisting the nut head off by trying to get it too tight. I realize this is silly because if I am able to do that with a 8 inch long ratchet then I need to be making TV appearances. Still, I have horrible memories of backing out broken oil pan bolts.


Thanks for the clarification, Gary T, and the adhesive failure you described is what happened to mine. But now I have 2 more questions. If the overthruster is supposed to dampen engine vibrations, wouldn't it need to be tuned to my specific engine, sort of like the counterweights that balance a tire? or is that already taken care of by the shavings & weight chips already on the crank shaft and this particular gizmo serves a slightly different function? An the second question, why not make the damned thing out of one chunk of metal if the adhesive is given to failure? Or is the rubber junk part of the vibration dampening arrangement?
#6
Old 06-30-2004, 08:44 AM
Member
Join Date: Mar 2002
Location: KCMO
Posts: 11,121
Quote:
Originally Posted by Inigo Montoya
If the overthruster is supposed to dampen engine vibrations, wouldn't it need to be tuned to my specific engine, sort of like the counterweights that balance a tire?
Essentially all the crankshafts in that size engine have the same balance characteristics. They don't have significantly different individual imbalances like tires do.

Quote:
An the second question, why not make the damned thing out of one chunk of metal if the adhesive is given to failure? Or is the rubber junk part of the vibration dampening arrangement?
Yes, the rubber is a critical factor in the dampening.
#7
Old 06-30-2004, 06:56 PM
Guest
Join Date: Jul 1999
Location: Chicago
Posts: 8,500
Not knowing what a harmonic balancer was, it sounded new-age-y to me when I read the title:

"With proper care, your Harmonic Balancer Quartz Crystal™ will sustain you through as many as ten reincarnations, should your karma require them."

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:38 AM.

Copyright © 2017
Best Topics: gas station cigars pig penises james gandolfini tattoos smell toast stroke raccoon smoke bombs frank zappa iq a2 teeth big toenail removal odyssey pax tires heinlein virginia edition crying buddha fm1 vs fm2 sua sponte dismissal tungsten steel sword distance eyeglasses how tugboats work value pak coupon famous duelists 2000s vs 2010s fondant taste chris jansing eyes swinging sticks personal packages orthogonal quantum states repair cassette tapes chicago river submarine mas means beetle license plates korean mixed script balloon pressure chromecast ps3 ghost email address can you declaw a dog what to do if you drink spoiled milk how to last longer your first time grandfather clock won't chime how much does a cholesterol test cost fuck em if they can't take a joke windows live mail error id 0x800ccc67 daisy chain power strips what is an ionizer native american man face is hawaii part of north america plumbers putty cure time eggs over easy in spanish what is a dinger in baseball glasses make my eyes look small was there helicopters in ww2 how much do my boobs weigh base metal bezel stainless steel back last of the mohicans war club is it better to do homework in the morning or at night standard shower head connection size lighting in the ocean die hard 2 plane explosion dish soap as hand soap how long do cheese slices last it is better for your seed to fall in the belly hard contact lenses plunger the load out stay jackson browne macallan select oak 1824 getting used to wearing glasses water on car floor after rain best place to live off the grid in us with great vengeance and furious anger