Kubota - Strange electrical buzzing

[berky]

Two basic voltage-drop measurements:

1. Master Ground wire
   1. Neg meter lead on BATTERY MINUS post (not on the connector!!!)
   2. Pos meter lead on ENGINE CASTING
   3. Measure voltage WHILE CRANKING ENGINE
   4. expect less than 0.050 volts (50mV)
2. Master power to starter
   1. Neg meter lead on BATTERY POSTIVE post (not on connector!!)
   2. Pos meter lead on LARGE wire on starter bendix
   3. Measure voltage WHILE CRANKING ENGINE
   4. expect less than 0.050 volts (50mV)

After you have checked the above two measurements, the results will lead us to the next step.
Anything more than 0.050v should be considered a problem.

So i didn't see this until after my last post.

I just went out to check these and the tractor started right up....

literally the only thing I did was used my rubber mallet to hit the negative battery terminal more onto the post (unfortunately I did this before trying to start it, so I don't know if it really did make a difference). I don't see how that would have changed anything since it's not like there's any corrosion or anything like that around them.

The voltage from battery negative post to engine was around 17mv give or take.

for the battery positive post to the wire on starter, I could not get access to the wire in it's current state. however, I'm assuming it would be fine since the damn thing started for me (multiple times I might add). I'm going to try it again tomorrow and see what happens and see if I can get into where the wire goes into the starter.

 

[Captain13]

NAPA carries the premade battery cables in stock (copper). At least they do here. Get the lengths and pick them up there if you are in a hurry.

 

[Mark_BX25D]

literally the only thing I did was used my rubber mallet to hit the negative battery terminal more onto the post

That's all it takes sometimes to get a poor connection to wake up and get to work. But it's also a good way to break a battery. Whacking the terminal like that can crack the post's internal connection. Might be a hairline crack that doesn't cause an immediate problem but will later. Not a good thing to do.

I don't see how that would have changed anything since it's not like there's any corrosion or anything like that around them.

It's very common for terminals to have a poor connection that isn't visible. The whack will break through the corrosioin, and because the posts are tapered, you will seat the terminal on more tightly.

You cannot determine the quality of a connection by eyeball. Take them apart and clean them. THEN you know they are good.

That's true of ALL connections, not just battery terminals.

Any time a vehicle isn't starting, and your battery measures good voltage at the posts, removing and cleaning should be Step 1.

 

[BruceP]

Any time a vehicle isn't starting, and your battery measures good voltage at the posts, removing and cleaning should be Step 1.

As an engineer, my "Step 1" is to TOUCH NOTHING and take voltage-drop measurements while imparting the least changes to the device. My goal is to isolate the problem so I can FIX it.

Usually, I can isolate ANY electrical issue within 5 minutes and KNOW what the problem is. (starting, charging, lights, electronics....etc)

I do not consider it a solid fix if I wiggle wires or clean something and the problem is gone. Without before/after measurements, I never know if it is fixed... or just went away temporally.

 

[Mark_BX25D]

As an engineer, my "Step 1" is to TOUCH NOTHING and take voltage-drop measurements while imparting the least changes to the device. My goal is to isolate the problem so I can FIX it.

As an engineer, I agree with you in theory.

But in the automotive world (which includes tractors), this us usually a very simple problem to solve, and does not benefit from being made complicated. A simple voltage test will tell you if the battery should have enough juice to turn over the engine. Since grungy battery posts are very common, and since they need to be cleaned anyway, cleaning them as step 1 is very much a "no harm done" item and solves the problem probably about 80% of the time.

For the other 20%, your likelihood of having clouded the issue with this simple cleaning is very small. Yes, it's possible, but not very likely.

K.I.S.S.

 

[berky]

Thanks everyone for all of the help and suggestions. I will definitely use this post as a reference if I run into similar issues. I will look at replacing some of the cabling probably this winter or if the problem manifests itself again sooner. I also bought myself a battery terminal brush and mechanics stethoscope today, since I was lacking that in my arsenal.

 

[Quick]

Thanks everyone for all of the help and suggestions.

Glad you got it fixed! (-:

 

[berky]

Just following up in case this it helps anyone else. The issue did come back after cleaning the terminals and such. So, I replaced both pos and neg battery wires with new ones. tractor started right up. Hopefully that was the actual issue. I'll post back if the issue comes back and I figure out something else to help fix it.