Crazy Tachometer - From Mud???

[CompactTractorFan]

Something strange happened today. I was getting ready to mow and I had the engine at/near full throttle. I was going through a muddy area and the tractor was covered in mud. I started to drive out of the area and all the sudden the tachometer went crazy. At one point it showed 4800 RPM. :confused2:

I started to mow and it was still going all over from 3,000 to almost 5,000 RPM. :confused2: I realized the tractor had too much mud caked on it to mow without making a mess, so I stopped and hosed it off somewhat...just got the worst of the mus off. When I started to mow again, the tachometer was back to normal. Do you thing it had anything to do with the mud on the tractor??? Strange...

 

[Short Game]

Was it going to low readings between the high readings? Sounds a little like a broken strand on the inner tach cable. Could be a dry cable too. Might just need grease. I suppose washing things could have done something, but it shouldn't have. Of course, this is assuming a mechanical, not an electronic, tach.

 

[Johndeere3720]

Was it going to low readings between the high readings? Sounds a little like a broken strand on the inner tach cable. Could be a dry cable too. Might just need grease. I suppose washing things could have done something, but it shouldn't have. Of course, this is assuming a mechanical, not an electronic, tach.

It is an electrical tach. As for the problem, I have no idea. :confused2:

 

[gwdixon]

I had the exact thing happen intermittently on a Kubota L3650. Finally, one day the tractor wouldn't start even though everything tested fine.

The culprit was a bad ground from the battery to the frame. The fix was a longer battery cable grounded directly to the engine. The tractor started instantly and the jumping tach problem permanently disappeared as well.

Check the electrical connections to the tach first to see if something is loose. Then use a battery jumper cable to ground the battery to the engine to see if the jumping tach clears up. If it does then a new ground is the suggestion. (Hint: remove the battery cable from the post during the test since there may be corrosion that is causing a bad connection.)

The mud situation that you experienced was likely a coincidence.

 

[PioneerMan]

I'm surprised your tach even goes to 5000, wouldn't want to see it get there...I think the tach on my truck only goes to 3600.

 

[CompactTractorFan]

Was it going to low readings between the high readings? Sounds a little like a broken strand on the inner tach cable. Could be a dry cable too. Might just need grease. I suppose washing things could have done something, but it shouldn't have. Of course, this is assuming a mechanical, not an electronic, tach.

No, it was going between the "normal reading" and the high readings...

 

[CompactTractorFan]

I'm surprised your tach even goes to 5000, wouldn't want to see it get there...I think the tach on my truck only goes to 3600.

It is digital...

 

[CompactTractorFan]

I had the exact thing happen intermittently on a Kubota L3650. Finally, one day the tractor wouldn't start even though everything tested fine.

The culprit was a bad ground from the battery to the frame. The fix was a longer battery cable grounded directly to the engine. The tractor started instantly and the jumping tach problem permanently disappeared as well.

Check the electrical connections to the tach first to see if something is loose. Then use a battery jumper cable to ground the battery to the engine to see if the jumping tach clears up. If it does then a new ground is the suggestion. (Hint: remove the battery cable from the post during the test since there may be corrosion that is causing a bad connection.)

The mud situation that you experienced was likely a coincidence.

Could be, but I used the BX today and no problems to report...

 

[gwdixon]

Could be, but I used the BX today and no problems to report...

Yeah, that's how it works (or doesn't work).

Just keep an eye on it and consider the electrical ground if it reoccurs.

 

[CompactTractorFan]

Yeah, that's how it works (or doesn't work).

Just keep an eye on it and consider the electrical ground if it reoccurs.

Will do...If that's the case, it will probably go to the dealer under warranty...