L4300 tach and RPM "surging"

sixdogs · Sep 3, 2013

I was finishing up rototilling 2 acres of new house lot today and suddenly I noticed the tach on my L4300 was surging. That is, bouncing--and I mean bouncing-- around by maybe 300 to 400 RPM. This sounds weird but I don't think the tractor was running any different. Maybe it was but I had just spent 4 hours at 540 RPM in tough ground with clouds of dust and it was getting dark. I was hunkered down with a dust mask and sunglasses, a tight hat and ear muffs. The engine may or may not have been acting funny but the tach sure was.

Anyway, I got home and blew out the sir filter, thinking that might be it. Nope.
Then I dumped the fuel out of the fuel filter thinking maybe water but no dice there, either. Plus I filter the fuel before it goes in anyway.

Not sure what to think. The tractor may have lacked some power but I really couldn't tell. I'll have to wait till mid-day tomorrow to check it out but does anyone have any idea on this or maybe could point me in a direction?

number two · Sep 3, 2013

I believe your L4300 has a cable driven tachometer.The surging you describe sounds like a "dry"cable(think speedometer cable)needing lubrication.It is possible to disconnect the cable from the tach,pull out the core and lube it and reassemble.You may also find the cable is about to break,causing the fluctuation in readings.A sharp kink in the cable sheath will also spell trouble.
If you find no problems with the tach drive,most likely the guage head is going south.
Good Luck!

sixdogs · Sep 4, 2013

number two said:
I believe your L4300 has a cable driven tachometer.The surging you describe sounds like a "dry"cable(think speedometer cable)needing lubrication.It is possible to disconnect the cable from the tach,pull out the core and lube it and reassemble.You may also find the cable is about to break,causing the fluctuation in readings.A sharp kink in the cable sheath will also spell trouble.
If you find no problems with the tach drive,most likely the guage head is going south.
Good Luck!

Number two you are number one on my list because it was indeed the speedometer cable. I would never have guessed that, at least not for a while.
So if other Kubota guys have a jerky tack and they have a mechanical cable, start with a dry cable answer. It's easy to grease, took me 10 minutes and that included time for an ice tea.