B7200 Electrical Problem

[Studebaker]

Help is needed on a 1987 B7200 with an electrical problem with 1,100 hours. I have an unknown load (short) issue when the ignition is turned on. Battery voltage is 12.55 volts with the key off. Turn the key on and the voltage drops to 4.5 volts. Thinking I just had a old battery, a new battery was installed. Same problem. Then I removed the starter and solenoid and bench tested to see if the load problem was a shorted starter. Nope. It ran and engaged good. Have checked the two fuses near the radiator. Both good. The manual shows a fusible link on top the starter, but there is none on my B7200. Could the regulator be the culprit? Would a defective glow plug(s) cause such a voltage drop? Other issues? Thanks for your help!
'Studebaker Man'

 

[MilkyWay]

Welcome to the forum Studebaker Man!
What do you have? 2 or 4 wheel drive? HST? The wiring diagrams are available on-line! Free!
https://apps.kubotausa.com/illustrated-parts/
Each machine has variations in wiring, so knowing which machine you have will lead to faulty circuit isolation more efficiently. Usually pulling fuses one at a time then checking for changes will work quickly.
It is hard for me to accept that a new battery is being drawn down to less than 6 V when the ignition is turned on, unless you also see smoke. Did you turn the key/ignition on before the starter was wired back in? Did the load problem still occur?

 

[D2Cat]

Have you removed the ground wire where it attaches to the tractor? Needs to be cleaned to bare metal. Are both battery wires in good condition under the insulation?

 

[100 td]

If indeed the voltage in your battery is still dropping to 4.5 volts, you either have a bad battery again, or there will be smoke and sparks coming from somewhere at many hundred amps. A shorted glow plug will draw a lot of current but is limited by the ~50A fusible link. If it has been bypassed, the wiring itself will limit current, but there will be a lot of heat and smoke from wiring.

I'm fairly sure there is a wiring diagram in this manual.
http://www.kubotabooks.com/AutoInde...Manuals/&file=B6200HST-B7200HST-WSM-01370.pdf

 

[twomany]

Just a note regarding the fitted fusible link.

On the B7200 H (two wheel drive) I have, the "Link" is nothing more than a short "U" of bare wire. The wire may be special stuff, Something to withstand oxidation when heated. But it looks just like a piece of bare wire.

I would look carefully at all the wiring to the lights both front and rear. Those run unprotected past raw metal clips etc. My tractor had several chaffe through spots on the rear lamp wires. Also, behind the "dash", is a likely spot for rodent destruction.
Even the switches can be faulty.
Look carefully at everything, One thing at a time.

eta

With only two fuses, "checking all the fuses" doesn't take long ;-)

 

[North Idaho Wolfman]

You have a bad battery connection or a bad battery cable.

If you were to lose that much voltage you would be seriously smoking something if it was a short!

 

[Studebaker]

THANK YOU gentlemen for your help! The problem was indeed a bad ground connection. Grass cutting can now commence again. Lessons are learned. 'Studebaker Man'