Got me stumped

[KYfarm]

Here goes. MF 1105, 6cylinder 354, last year tach
stopped working properly. Needle would climb all the way
to the right as as far as it would go and stay there. I
checked cable and both ends were square and it was
turning strongly. Figured tach was bad so ordered a new
one. Put it in same problem. Hmmm. Went ahead and
bought a new cable from this site. Didnt help.

Took old tach apart and there is a small spring on top of
the flywheel that was rusted and broken, ok, old tach
had obvious problem. Took cover off new tach and spring
is intact. Tested new tach on bench with both cables and
drill and it works perfectly, install it on tractor, needle
goes all the way to the right.

Very frustrating, if the drive gear in the injection pump
was bad seems needle would jump around or read slow.

Also new tach doesnt have broken spring old tach did.

Any help is appreciated

 

[Dieseltech]

Loosen the tach mounting stud nuts and see if that helps, maybe the case is distorted somehow causing the trouble. The tach cable drive either works or not so I doubt any engine/cable drive trouble there.

 

[IndyFarmBoy]

On our MF 285s, there is a little mechanism that bolts on the lower front of the engine (driver's right) that has a gear that goes into the engine and then out the top of the mechanism is where the cable screwes in. I had one of those go bad but the tach didn't work at all. . . but I messed with the tach a lot on ours to get it to work and that is the only piece I can think of that you didn't mention, if it is even present on the A6.354. Other than that it just sounds like a bad tach. . .definitely puzzling as you say.

 

[Janicholson]

I agree. twisting sideways on the cable attachment is likely. Testing it unmounted will assess that. it might just take a wire tie to pull the cable end straight. Jim

 

[KYfarm]

Thanks for the replys.

When testing in the tractor Im just setting it loose in the hole in the dash, havent used the hold down bracket yet.

My thought was if it works loose on the bench with a drill it should work loose in the dash. I should try mounting it in the dash just to try and see if that makes a difference although I dont see how it would.

Its these simple repairs that can be frustrating sometimes.

 

[KYfarm]

This is the mounting point for the driven end of the cable, mounts under the injection pump.