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Case 580K Volt meter/Alt./Tach Going Wonky

P

pdhntr

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Joined
Apr 26, 2016
Messages
21
Location
No. Wis.
Mid to late 80's 580K. Was running it, pushing back snow banks. Running fine and all of a sudden the tach would swing to zero, then start again, swing to zero and restart. At the same time the volt meter started going up into the red area. This happened several times with the tach but still occasionally works. But the volt meter when running is up in the high green to low red area.

I tried checking the connections on the back of the instrument panel, and on the back of the alternator, and nothing is helping. Now the alternator light comes on faintly as if the alternator isn't working.

Any help would be appreciated, no one in the area to call.

Thanks.

Jim
 
P

pdhntr

Member
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Apr 26, 2016
Messages
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Location
No. Wis.
After doing some research on the net, it seems the tach is run off the alternator. So if the alternator went bad, it could have made the tach jump around?

Is this all pointing to replacing the alternator??

Thanks.

Jim
 
AllDodge

AllDodge

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Apr 2, 2011
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Location
Kentucky
Is this all pointing to replacing the alternator??
Click to expand...

Yes tach runs off ALT and so far this would lead me to the ALT

Start it up and get the rpms up above idle and then measure the output from the ALT. If its above 14.5V then have it rebuilt
 
catskinner 10

catskinner 10

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Retired Operator/Master Mechanic 55Yr Member IUOE
Check the Cluster Ground.
Also the main harness plug at the cluster.
If the gauge cluster looses it's ground or is weak all the dash systems are affected.
Tom
 
D

Delmer

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Check ALL the connections, even battery ground cables. Then replace the voltage regulator if it continues. Nothing wrong with the alternator or belt if you have high voltage.
 
P

pdhntr

Member
Joined
Apr 26, 2016
Messages
21
Location
No. Wis.
Delmer said:
Check ALL the connections, even battery ground cables. Then replace the voltage regulator if it continues. Nothing wrong with the alternator or belt if you have high voltage.
Click to expand...

Sorry Delmer, in my original post I was trying to be brief, but the last minute or so I let it run, the volt meter quit showing a high voltage condition and was showing 12 volts, and the alternator light started glowing slightly. Revving the motor did not move the voltage meter needle as it usually does.

I checked the belt, it is tight.

I checked the cluster connections, but have not found the ground for the cluster. Can someone point me to where specifically it would be? I will clean the battery connections and try again.

Thanks for all the information so far. I really appreciate it.

Jim
 
AllDodge

AllDodge

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With it going from a high voltage to 12V, sounds like it just fried the diodes and/or regulator. Your now just reading battery voltage
 
P

pdhntr

Member
Joined
Apr 26, 2016
Messages
21
Location
No. Wis.
AllDodge said:
With it going from a high voltage to 12V, sounds like it just fried the diodes and/or regulator. Your now just reading battery voltage
Click to expand...

That is what I was thinking also. I fried something.

I was running it for a couple minutes, shutting it off, tapping on the black thing on the back of the alternator, (voltage regulator??) and then shutting it off. Checking the cluster plug ins, looking for shorted wires, running it again, shutting it off, etc.

It finally quit showing a high voltage, and the alternator light started to glow faintly.

I will pull the alternator tomorrow and see if I can find some place TRUSTWORTHY to test the alternator.

Thanks.

Jim
 
P

pdhntr

Member
Joined
Apr 26, 2016
Messages
21
Location
No. Wis.
pdhntr said:
I will pull the alternator tomorrow and see if I can find some place TRUSTWORTHY to test the alternator.
Click to expand...

It was the alternator. I took it too Chippewa Valley Alternator and Starter and had it tested. Got a new one with 95 amps. Ran the backhoe for an hour this afternoon and no problems.

Thumbs up to Chippewa Valley. Good outfit.

Jim
 
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