M35A2 Tach not working

[Lenny]

I pulled the cable out of the tach and noted that it does not turn with the engine running. I'm thinking of course cable, or gears in front of the engine etc, but I haven't investigated any further yet. So before I start taking stuff apart I thought I'd ask Is anyone aware of any common problems with these trucks that cause this. Thanks, Lenny

 

[M35A2-AZ]

If you could pull the cable out, then cable is broken. There is keepers on each end to keep you from pulling it it out.
So I would say the cable is broken. It does happen if you do not keep it lubed.

 

[Lenny]

I also noticed a couple of other things that I didn't mention. The cable spins freely in the surrounding jacket. Also that the cable will pull out about one inch and then it gets stuck. I didn't try to force it. If the cable is broken like somewhere in the middle is there a retainer that keeps me from pulling it out all the way on the tach end? And if it is broken I guess I'm going to have to disconnect it at the front of the engine too to get that piece out. Does that sound correct? Judging by the speedometer cable on my bicycle, (I know no great similarity there), if you pull the cable out at the speedo end it turns freely because it's not engaged with the gear at the wheel. This RPM setup must be a similar thing right? Thanks, Lenny

 

[M35A2-AZ]

You have to take the retainer off at the motor end to pull it all the way out, if it is not broken. It may of just broke the end off at the motor.
I would just try to push it back to the motor end and see if the motor turns it. It may not be engaging at that end, or it is rounded.

 

[dmetalmiki]

As previously mentioned, this is one oft times neglected item to be serviced, (and), Due to the sharp angle of the cable at the front of the engine, this a common failure point. You need the complete cable inner and outer. (then) Keep it lubed. graphite, or molyslip and oil mix keeps them turning (the clocks) smoothly, and lengthens the longevity of the inner cable.
The gearbox rarely fails.

 

[Lenny]

I would be able to remove the two broken lengths from front and tach end has anyone ever successfully replaced just the inner cable? I guess that I should ask if it's even available. Lenny

 

[Lenny]

Has anyone used one of these? They're about 5.00. Thanks, Lenny

https://www.google.com/search?q=tac...=Yj0aV53vLorr-AHt_Y3wBg#imgrc=9lDb6WFhj0fCnM:

 

[M35A2-AZ]

Here is one from Erik's $40
http://www.eriksmilitarysurplus.com/tadrcam3andm.html

 

[Lenny]

That's definitely cheaper than 67.00. Thanks, Lenny

 

[Flyingvan911]

Erik's usually has good prices. They are good people to deal with.

 

[WillWagner]

When the cable breaks the little frayed pieces parts of the cable chew up the housing. Usually, if a new cable alone is replaced, it will fail pretty fast because of the damage to the housing.

 

[Lenny]

Makes perfect sense. I'll forgo the rebuild. Thanks. Lenny