I changed this on my rig a month back. The new balancer cost $ 192.50 from Cummins Northeast.

quote:

Originally posted by bill h:
It strikes me as a bad design feature to have the belt engage the outside, putting stress on the layer of rubber.

Yep... it is.

quote:

Originally posted by Bill N.Y. ~ Posted 03-09-2006 07:03 PM:
Cummins will have you believe they do not see alot of this: On trucks, buses, motor homes I have seen these fail. The design with the pulley attached to the wrong side is a "flub" that has been around far too long.

Here is a possible solution: http://fluid-damper.com/fluida...luidampr-cummins.htm

quote:

Originally posted by noble97monarch:
It is located on the engine Crankshaft and is designed to dampen the vibrations created by an inherently unbalanced engine, which most are. The reason it is important to your alternator is that the crank pulley (bolted to the dampener) is the "drive" pulley for all your engine driven items like alternator, water pump, fan (if not electric or hydraulic). Therefore, if the dampener is shot, it can play havoc with the belts and the seals. In extreme cases it can come apart and cause impact damage too.

Maybe I am being a little picky (!) – the reason for a harmonic balance is that the crankshaft will flex with the firing of each cylinder (less than a degree). At specific frequencies (engine RPMS) this can have a resonating effect that will amplify the flexing, which in turn creates additional metal fatigue in the crank and can increase bearing wear.

You cannot cure this by balancing the reciprocating/rotating components, its just a fact of life for engines with significant power output.

It the case of the old big block Chevy race motors from the Can Am days it actually changed the ignition timing since the distributor was driven off one end of the crank, the flexing of the crank was enough to change the ignition timing by a couple of degrees (a bad thing for race engines!)

quote:

Maybe I am being a little picky (!) – the reason for a harmonic balance is that the crankshaft will flex with the firing of each cylinder (less than a degree). At specific frequencies (engine RPMS) this can have a resonating effect that will amplify the flexing, which in turn creates additional metal fatigue in the crank and can increase bearing wear.

Me thinks we're saying the same thing.
Wikopedia:
Vibration refers to mechanical oscillations about an equilibrium point.

I didn't know about the timing shift in severe applications, that's interesting.

quote:

Originally posted by Tom K:
Here is a possible solution: http://fluid-damper.com/fluida...luidampr-cummins.htm

This sounds like the type of damper that Bill, NY and others are recommending.

I copied this sentence from the link to the fluid-damper website referenced by TOM-K. "The best dampers on the market are manufactured in the U.S.A. by Horschel Motorsports,..." Does anyone have experience with this brand of damper for the Cummins 5.9 diesel (1991 vintage)? If not recommended what other brands do you recommend?

quote:

Originally posted by noble97monarch:
It is located on the engine Crankshaft and is designed to dampen the vibrations created by an inherently unbalanced engine, which most are. The reason it is important to your alternator is that the crank pulley (bolted to the dampener) is the "drive" pulley for all your engine driven items like alternator, water pump, fan (if not electric or hydraulic). Therefore, if the dampener is shot, it can play havoc with the belts and the seals. In extreme cases it can come apart and cause impact damage too.

After reading this post by Noble97 it got me thinking about some of the other problems that I have had with things attached to the serpentine drive belt since buying the coach in late 2006.

(1) The water pump went out in Canada in 2007 and was replaced with a rebuilt unit. It was the original pump and had visible wear & minor corrosion.
(2) The alternator bearings froze up in Oregon in 2009 and the alternator pully quickly ate it's way through the serpentine belt. The bearings were replaced but not the pully. the alternator was replaced in 1998 and rebuilt in 2002.

The erratic readings on the voltmeter and some oil pressure & temperature readings that were off slightly on this trip makes me think that the damper may be the problem, expecially since the readings all tend to "settle in" after driving for 20 - 30 miles. A visual inspection of the belts & pulleys shows that the belt & pulleys are all tracking straight ... however there is a slight metallic noise.

Is there a way to visually check the damper without removing it?

Carl Feren

quote:

Originally posted by Carl Feren:

Is there a way to visually check the damper without removing it?

Carl Feren

I don't know about the Cummins, but on gassers, I always paint a white stripe going from the inner hub to the outer ring, straight across the rubber. Any permanent shifting or slippage will be easily seen, but, as in the early stages of failure, if it moves around when running and returns to its original position, you might not detect it.

I think if I had one I suspected of shifting or wobbling while running, I would check it at cranking speed with a dial indicator with a roller tip. If that didn't show anything, I would check it using the freeze-motion strobe effect of a timing light, connected to an ignition wire......................OOPS, no ignition. Well, OK, then, I would cobble up an adjustable bolt that would be very close to the outer diameter of the pulley, and see if it left any witness marks for checking radial movement. Same thing for lateral movement. This can also be done with less precision by just holding a screwdriver near the pulley.

This is all from a non-diesel guy, so please share anything you hear from Cummins. They should be able to quote you runout limits, etc.

quote:

chrisW: It the case of the old big block Chevy race motors from the Can Am days it actually changed the ignition timing since the distributor was driven off one end of the crank, the flexing of the crank was enough to change the ignition timing by a couple of degrees.

It is even worse for our gasser engines. The power goes to the transmission from the back end of the crank, but the timing comes off the front of the crank, through the timing chain, then all the way back to the rear of the engine by way of a camshaft that can have end float and flex. Then, it uses the same set of gears back there that drive the oil pump. The gear type oil pump introduces its own impulses to the distributor shaft, causing up and down movement on the spiral drive gear. And the shaft has some resonance and flexing of its own. Then, up in the distributor, we have bearing slop, end play and the loosey-goosey centrifugal advance mechanism, as well as the vacuum advance clearances. Anybody who remembers the old distributor testing machines (or an Allen scope) will probably remember how there was always spark scatter on the degree wheel. And, it changed as the different forces worked independently to either cancel or augment each other.

Later engines take the spark impulse signal right off the crankshaft, eliminating everything but crankshaft flex. My LT4 Vette engine does it halfway and has the distributor directly mounted to the cam on the front, eliminating all but cam drive chain slop.

quote:

Originally posted by Carl Feren:
Is there a way to visually check the damper without removing it?

There is a notch - also look for excessive runout while using it.

As stated earlier...

quote:

Originally posted by Bill N.Y.:
Because of the age of these coaches, and the design of these harmonic balancers, we now have 2 types of people on our forums... Those that have replaced their balancer and those who will soon be replacing them...

In this same post and elsewhere...

quote:

Originally posted by BillNY. There is a notch - also look for excessive runout while using it.

How do I use the notch, Bill?

I have not noticed any visible runout from the side but will get underneath as I have a clear view from there without removing anything.

When we get to CT I plan to check this out & will probably replace it with a fluid-dampmer as you recommend Bill.

Look to see if the notch, or line, is inline with the inside and outsides of the damper. Look for cracking of the rubber between both sides.

There is "less chance" of a 5.9l damper having an issue Carl - the 8.3l's had the most problems - Have it checked out before investing in a new damper Carl.

Now, if you want to pamper your Barth, then invest in a new fluid damper. Heck, it's only money.

1.

quote:

Originally posted by Bill N.Y.:
Heck, it's only money.

2.

quote:

If it ain't broke, don't fix it.

Choose one.

quote:

Originally posted by bill h:
1.

quote:

Originally posted by Bill N.Y.:
Heck, it's only money.

2.

quote:

If it ain't broke, don't fix it.

Choose one.

3. If it ain't broke, fix it 'til it is!

Testing and diagnosing is worth it. Blindly replacing items is usually more expen$ive in the long run. Paying for proper diagnosis is usually cheaper.

Inaction could cause catastrophic results if the harmonic balancer just decides to blow up on him.

Here is Eric, a 5.9L owner, and his harmonic balancer came apart on him in April.

quote:

Originally posted by Eric Herrle:
I’m just starting dismantling the back end of my Breakaway to replace the Harmonic balancer…(another 1000 feet and it would have been an uncontained explosion)

As an FYI... Eric's coach# is 5 digits off of yours in the data tag project and 13 off for the vin#

Yes, now might be the time before it's too late.

quote:

Originally posted by Bill N.Y.:
Because of the age of these coaches, and the design of these harmonic balancers, we now have 2 types of people on our forums... Those that have replaced their balancer and those who will soon be replacing them...

Bill NY: Carl Feren & I have same year & model coaches. Should I put my name on the "do it now list)? My power plant is plain Jane with no extras....................