Varying Carb Heat Cable Resistance

[Graueradler]

Flew recently. At run-up, force required to operate carb heat lever was normal. Mechanic doing annual inspection noted yesterday that it was difficult to operate. I found it the same way. We talked about the need to lube it. I taxied from hangar to run-up pad prepping to warm up engine for compression test & oil change. At run-up, it was again totally normal. What is going on

(1971 Cherokee 150 Flite-Liner)

 

[JOhnH]

Flew recently. At run-up, force required to operate carb heat lever was normal. Mechanic doing annual inspection noted yesterday that it was difficult to operate. I found it the same way. We talked about the need to lube it. I taxied from hangar to run-up pad prepping to warm up engine for compression test & oil change. At run-up, it was again totally normal. What is going on

(1971 Cherokee 150 Flite-Liner)

Could he have lubed it when you weren't looking?

 

[Dan Thomas]

Might have some grunge in it that softens when engine heat warms it up.

Or the torque and/or thrust are doing something to it.

Dan

 

[SoloEqs]

Get out there and look at the cable housing, see if it's got any kinks or twists, then check the angle of the cable and housing at the end. I've seen more than one plane which had a clamp pointing the cable somewhere other than the control arm.

With the engine RUNNING, the vibration was enough to "shake" the cable "loose" inside the housing and overcome the resistance.

 

[Graueradler]

Could he have lubed it when you weren't looking?

Nope. It didn't get lubed.