Harmonic Balancer Movement

[dhochsprung]

I have a 67 Barracuda with a 1971 340 in it. I am trying to locate a knocking noise that appeared recently. The noise frequency increases with rpm and does not disappear when engine is warmed up. I disconnected belts to altenator and power steering and noise did not disappear. However, I noticed that the crankshaft pulley was not spinning straight. I grabed the pulley and there is some side to side movement. Pulley is not loose on balancer so I think the balancer is moving. Can anyone tell me if there should be any movement of harmonic balancer.

[cutting torch]

It sounds like the balancer may be loose on the crank. If it's loose enough to twist, the knock could be the balancer hammering the woodruff key.

torch

[dwc43]

or worse, the thrust bearing is gone and the crank is moving around.

[jelsr]

There should be no movement, period!

[dhochsprung]

Yes, there is rotational movement of the balancer when I turn the crank pulley by hand. Hopefully only the key or balancer is damaged. Thanks all for your input.

[cutting torch]

I hope it didn't hurt your crank.

torch

[cutting torch]

Originally Posted by dwc43

or worse, the thrust bearing is gone and the crank is moving around.

How is that supposed to let his pulley/damper move side to side?

Sometimes I think you type faster than you think! Relax..... Slow down.......

torch

[ehostler]

Sounds like you need a new balancer. I hope that you haven't run it long in this condition. A balancer that messed up can cause other failures.

[dhochsprung]

At first, I thought it was side-to-side movement of the balancer. But rechecked it after your post about key being loose. There is no side to side or in and out movement of the balancer; only rotational movement (about 1/8to 1/4 inch).

I noticed the noise about 3 weeks ago but have not driven much in those three weeks. Other than this knock,the car has been performing as normal. However, yesterday, the car started to idle rough and stalled sometimes. After checking balancer movement, I replaced alternator belt but not with normal tension. So hopefully the battery is not being charged enough to insure proper voltage to ECU. I will check that today. Otherwise, I plan to take the car to my engine guy and have him check it out. Wish me luck.

[dwc43]

Originally Posted by cutting torch

How is that supposed to let his pulley/damper move side to side?

Sometimes I think you type faster than you think! Relax..... Slow down.......

torch

For and aft movment could make it bang on the cover. He did not seem sure to me as to what it was doing at the time. Just threw it in there. Never seen one move side to side, rotate on the shaft, yes as well as for and aft.Have seen the outter ring come off of one before too.

[pishta]

Originally Posted by dwc43

For and aft movment could make it bang on the cover. He did not seem sure to me as to what it was doing at the time. Just threw it in there. Never seen one move side to side, rotate on the shaft, yes as well as for and aft.Have seen the outter ring come off of one before too.

Balancer legend---Old chevy truck, belt broke, and the ballancer literally came off, dropped to the ground and raced down a side alley. Those things were pressed on!

[jelsr]

Back in the '60's (when I was working for a living) we had a bunch of Chev trucks with 292 hot water sixes. (KDOT) The dampers gave up the ghost on a regular basis but it always moved back and ate a hole in the timing cover, never seen one go to the front. When they went it is was pretty quick cause in those days we were required to do a service check (tune up) every 12000 mi. and if it had moved you couldn't get the timing even close.

[dwc43]

Originally Posted by pishta

Balancer legend---Old chevy truck, belt broke, and the ballancer literally came off, dropped to the ground and raced down a side alley. Those things were pressed on!

Watched Freddy Prosser cut the outer ring off a balancer at a dirt track one night so he could get back into the next race. Used a torch on it. The outter ring was just spinnning around the inner ring. No rubber to be seen between them at all.

[BJSracing]

I had one come off a poly 318 about 7 years ago. And of course I was going 110 mph. that was fun while it was beating the bottom of the car on the way out. Put a new one on and drove it for another3 years.

[dhochsprung]

After all your stories of balancer failures, I decided to take off the crank pulley and see if the balancer was damaged. Well, the balancer was not damaged but the bolt attaching it to the crank was loose. So the balancer had paritally slipped off the crank key. Do not see any damage to mating surfaces of balancer or crank. If I had driven the car much longer, I would have had a real spectular story to post. Dodged that bullet.

[Tarrbabe]

I had a 327 66 Nova that the balancer got loose on. More than once when I would rev it past 7000 rpm the balancer would leave the engine and go a hundred yards to the right.
Anyone ever wonder why I became a Mopar fan? That was one of many.
Plus, I got tired of getting beat by those damn dodges and plymouths.

[dhochsprung]

Needless to say, I have to replace the balancer. I can slide the balancer on the crank by hand. Any recommendations for a replacement? I have read in previous posts that the CAT balancer (fluid type) is mentioned. My only concern is the dimensions of replacement so that I do not have alignment problems with the crank pulley for belts.

[pishta]

Originally Posted by dhochsprung

Needless to say, I have to replace the balancer. I can slide the balancer on the crank by hand. Any recommendations for a replacement? I have read in previous posts that the CAT balancer (fluid type) is mentioned. My only concern is the dimensions of replacement so that I do not have alignment problems with the crank pulley for belts.

CAT is a good piece in my book, I had one and it ran well and was exceptionally well built/engineered. Get a later model that has the countersunk pulley mount pad as the original "race" ones were thicker than a stocker and didnt come with a longer crank bolt! Also the bolt pattern is symetrical so you may have to elongate 1 hole in your pulley to match up (common)

[cutting torch]

I've used a few Romac dampers, and they were a very tight fit to the crank. That could be a good thing if you lost any meat off the crank.

torch

[dhochsprung]

I ordered a CAT fluid harmonic balancer. Their tech support said it was dimensionally the same as the stock balancer. However, I received it today, and sure enough, it is not the same. The stock is 2.5 inches wide and the CAT is 3 inches wide. So if I pressed it on to the crank, won't it extend 1/2 inch further away from the engine cauing the crank pulley and belts to misalign? Also, one of the mounting holes for the crank pulley does not line up. This looks like the race balancer in Pishta's reply. I did not see another fluid balancer for a 340 on their website. Anybody know of any easy fix?

[pishta]

They make a big block damper that is "redesigned" with a countersunk pulley mounting pad. I had to shim all my small block pulleys (1) and get a longer bolt to attach the damper. I used a few washers under the water pump pulley and flipped the pulley off the alternator shaft. It all lined up, but dont say I didnt warn you. That or get a custom lower pulley made.

[dhochsprung]

Thanks, for the info Pishta. I guess I will return the Cat balancer rather than modify existing belt alignment and go with stock balancer.