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94 Flair Motothome w/93 6.5L - Harmonic Balancer Qestions

lrpierce

lrpierce

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Shreveport, LA
This picture is taken lying under the engine looking up at the bottom of the harmonic balancer. You'll notice there is an extension off of the pulley that provides the pulley mount for the fan. When the engine is running, there is a slight up and down, maybe even a wobbling movement of the balancer, which is multiplied by the extension piece at the fan pulley end. All of this causes the belt tensioner for the fan to really dance around. I will take the belts off and check for play and all of that. Any ideas on what to look for and check while I have it apart? Is it possible that the crank could have some play in it at this end? If the balancer is bad, will I be able to move it by hand? Just looking for some thoughts. I will try to get a video of it also. I am worried about messing up the crank. Thanks, Les
(Also, although the chassis manual says it is a hydraulic fan, I believe it is just a belt driven flex fan.)WP_20150721_012.jpg
 
You really should remove, clean, inspect all the parts connected to the crank... replace the HB if unknown age-miles, also the belt pulley has rubber so it should be replaced at the same time... The extension should be inspected well and cleaned to ensure it isn't bent...

With these parts it's a good idea to replace with new if there is any doubt, and remember the HB gets torked to 200 ft lbs, not a easy task .... and don't cheap out n the parts either, but AC if possible...
 
Bent makes sense. So would loose. Nothing else wobbles the fan belt. The engine belt is on a ball bearing and damper so it won't (shouldn't) wobble.

Post some better pics of the fan clutch already! :p
 
Burning oil said:
Why all that contraption anyway? Was it to relocate the fan?
Click to expand...

This is all mounted in the rear of the motor home with the front of the engine facing towards the back end of the coach. (A poor mans diesel pusher), When you open the back "hood" you are looking at a rather massive radiator. Engine is accessed either underneath, or inside through a large door under the bed in the back. I would imagine airflow was a problem? It is an Oshkosh chassis.
 
WarWagon said:
Bent makes sense. So would loose. Nothing else wobbles the fan belt. The engine belt is on a ball bearing and damper so it won't (shouldn't) wobble.

Post some better pics of the fan clutch already! :p
Click to expand...

I will, but I don't think there is a fan clutch. It looks like it is solid mounted and is a flex fan. I'll try to get over to the storage yard and check it out for sure. I could be way off base, it's happened before :) More pics to come and maybe a video.
 
Still haven't had a chance to tear into it, but here is a video of it running. I think the phone camera is stabilizing the image some, because it seems worse than this live. I know there are rubber components of the balancer and the pulley, but this piece that drives the fan belt seems to be bolted to all solid parts. Keep and eye on the fan belt tensioner. The motorhome is now in a park and the manager says I can't work on it there, but I just might sneak under there when he's not looking, either that or pay someone to do it. (Which goes against my grain).

 
so in the video, it appears the fan hub itself is running true, but the harmonic balancer and the extension pulley are what is wobbling?
 
I hate Commie places like that that won't let you work on your rides. Suggest you find another RV park that will. They can do without your money. Talk about freedom and rights infringing!

Depending on how this is bolted on is may or may not be normal. Looking through the center of the crank fan drive pulley we need to see of it is held on by the 4 serpentine pulley bolts or has a rubber element of it's own. IMO it looks like it is loose. Now this can be from a rubber element and be normal or shot and that's what we need to find out.
 
Well, I am parked in the back row, and the engine is in the back, so I might just take it apart down to the HB and see how true all of those parts are. I don't think anybody could tell what I was doing under there LOL. How hard is it to get this balancer off and a new one on. Can it be done quietly? :rolleyes: Thanks everyone, will update when I have something to update. Les
 
Well, been a while but I bought a good flashlight and took another look: What appears to be happening is the engine "jumps" a little when idling, like most do, and because of the extra length of the extension this movement is amplified at the fan pulley. It causes the fan tensioner to bounce around quite a bit because the lower fan pulley is mounted to the engine and the upper pulley that drives the fan is mounted to the chassis, so the belt tension is constantly changing to keep up. So what do you think? Motor mounts, maybe? It seems to idle pretty smoothly to me. Poor design, LOL?
 
If the engine moves very much when accelerated from an idle, new Energy Suspension mounts would help. Also sounds like a poor design.
 
lrpierce said:
Well, been a while but I bought a good flashlight and took another look: What appears to be happening is the engine "jumps" a little when idling, like most do, and because of the extra length of the extension this movement is amplified at the fan pulley. It causes the fan tensioner to bounce around quite a bit because the lower fan pulley is mounted to the engine and the upper pulley that drives the fan is mounted to the chassis, so the belt tension is constantly changing to keep up. So what do you think? Motor mounts, maybe? It seems to idle pretty smoothly to me. Poor design, LOL?
Click to expand...

IMHO, get a FluidDamper as the extra vibrations of that contraption that "the GM balancer was not designed to eliminate the additional rotational mass" will eventually take out that diesel, convert back to single belt and fan/clutch assembly, extend the shroud. Another way (expensive) is too do is a standalone (mounted in it's own frame) belt driven big fan like used in commercial bus builds and get the 3 belt hub and drive the fan from the inner most pulley.
 
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