Problems in west Texas MCI 5a

[Damn Yankee]

I was having the same problem on my 5 and found that one of the rear bolts (closest to the pulley) that hold the gear box to the mounting plate was missing and the gear box seemed to be bouncing up and down throwing the belt. Replaced the bolt and worked better but then the belt would turn on its side. I figured the spring was getting weak so I removed the pulley and welded the two halves together in the bottom of the v groove. You could also bolt them together. Worked like a charm. No belt problems since. You just need to check the belt tension more often. You can also replace it with a solid pulley.

[Ed Hackenbruch]

Bob, i don't suppose that you saved the spring?

[Jaime]

Damn Yankee, I have checked all the bolts except I do not seem to have number 1 in the below diagram. The diagram is for a 1966 MCI 5 I have a 1967. are those the bolts you mentioned? I have never had them I might need to get them.

[Garymci5]

If alignment and tension are acceptable might be worth removing the belt to inspect it for damage or extreme warping, including the pulleys.  Might try reinstalling the belt backwards to help prevent it from jumping. However proper tension and alignment are key.

My MCI 5a has a solid pulley bracket, most likely made by the prior owner, possibly for the same reason.  I run the belt tight enough to prevent major chaffing on the tension side on the blower box "floor".  Greased the pulley with high-grade synthetic to be safe.

It's possible the engine has a failed motor mount and caused enough movement to change pulley alignment/tension (?).

Good luck!

[Jaime]

Thanks for the reply Garymci5 I will check the motor mounts, but it looks like the issue was resolved by the penetrating fluid. of course time will tell and it does seem that folks have eliminated this pulley system from their rigs and I may want to do the same.

[Damn Yankee]

Ed: I left the spring on just in case the welds failed.
Jamie: I never knew there was a #1 to loosen. I just adjusted it with # 2 & 3. To check the blower drive mounting bolts you need to get a flash light and look down over the top of the pulley or just reach in and feel for them (1 on each corner) and check if their tight with a socket. If your rubber mounting bushings have been oil soaked they will get very mushy over time and will need to be replaced.

[Ed Hackenbruch]

Jaime, if you do change over to a solid pulley i would be interested in the old one.

[Jaime]

Ed Hackenbruch I will keep your request in mind. I am planning on arriving home tomarrow night and then I plan on tearing it down to clean and examine all the parts in the next few weeks. it is a mess in the fan bay right now lots of rubber dust from the belt when it was not riding correctly. I have also replaced the belt with a new one. 

[Garymci5]

Thanks for the reply Garymci5 I will check the motor mounts, but it looks like the issue was resolved by the penetrating fluid. of course time will tell and it does seem that folks have eliminated this pulley system from their rigs and I may want to do the same.

Curious as to what was actually done with that penaltratin' fluid! Sounds like something was stuck....?

[Jaime]

Garymci5 I don't understand it myself I looked at the way this works and it does not make a lot of sense to me that it would ever work, but it does work the pulley separates against spring pressure vs centrifugal force(gyroscopic effect) and the pressure should keep it evenly spaced and according to the book dynamically balanced. The issue I appeared to have is that the pulley was separating unevenly, so I suppose it was binding but for the life of me I do not know were. it appears that half of the pulley free floats against the pressure of the spring. if some does know I would be interested in the answer myself. it worked so well when I head out tomarrow from El Paso I will be heading to ALBQ NM instead of home as long as I have no issues on the way From I 10 to I 25