Oil/Temp Gauge Spiking (and smoking)

[gride7]

Today I decided I was tired of having no lights in my gauges at night and decided to pull the dash apart in my '73 sii. The oil/temp gauge was working fine (except the bulb) and the alternator/fuel gauge was half working. The alternator needle moves around but the fuel gauge stays on e no matter what.

I pulled the alt/fuel gauge 1st and let it hang by the wires. I then removed the oil/temp gauge. I then proceeded to unplug the oil/temp gauge and take it apart to clean it out. Not thinking about it I realized the alt/fuel gauge was resting against the metal dash and I had not unhooked the battery. I immediately put the gauge back in the dash to keep the wires off the metal and unhooked the battery.

When I reinstalled the gauges and turned the key on the oil/temp gauge then peaked (both needles) and a little puff of smoke came out of the gauge itself. I immediately turned the key off and unplugged the gauge.

At this point I cannot plug the gauge back in without this happening every time. What happened? Did I short the system? Did I ruin the voltage regulator on the back of the oil/temp gauge?

Please help! Thanks!

 

[Eric VanBuren]

Yea it sounds like you May have shorted out the sender side of the gauges, did you remove them from the actual housing if so I would suspect problems with positioning of the studs where they pass through the housing or the paper insulator that goes between the gauge and housing.

 

[gride7]

yea it sounds like you May have shorted out the sender side of the gauges, did you remove them from the actual housing if so I would suspect problems with positioning of the studs where they pass through the housing or the paper insulator that goes between the gauge and housing.

Not sure, I'll have to disassemble the gauge again and check. I did notice that a couple of dried out pieces of black tape fell out when I opened it. Looked like one between the individual gauges in the middle and one on each side between the gauges and the housing.

So if the gauges themselves make contact with the blue housing that could cause them both to peak? (sorry I really know nothing about the electric system but trying to learn as I go)

and to be more descriptive, when I turn the key in the ignition one click the temperature gauge will begin to rise until it peaks. Not until I actually crank the Scout will the oil pressure gauge begin to rise until it peaks.

Thinking back I really can't remember if I noticed the gauges peaking before I disassembled the entire housing to clean it out. My theory was that while the battery was still connected and the fuel/alternator gauge was hanging out of the dash that the two poles on the alternator gauge touched on the metal dash and shorted out something. Is that possible and if so what would it short out? Could that have killed the cvr on the back of the oil/temp gauge next to it?

Thanks,
g

 

[Scoutboy74]

If the wires connected to the amp gauge had come in contact with metal, it would have produced robust sparks, followed by smoke and the pungent odor of melting plastic if left unattended for long enough. Those wires conduct the main voltage feed between the battery and the alternator and are hot all the time as long as the battery is connected. The brittle black tape that fell out was most likely used to help keep the l----h backing plate in place and not for any kind of electrical insulation.

 

[gride7]

if the wires connected to the amp gauge had come in contact with metal, it would have produced robust sparks, followed by smoke and the pungent odor of melting plastic if left unattended for long enough. Those wires conduct the main voltage feed between the battery and the alternator and are hot all the time as long as the battery is connected. The brittle black tape that fell out was most likely used to help keep the l----h backing plate in place and not for any kind of electrical insulation.

I did not see any big sparks but I did hear a weird noise. All I did was unscrew the gauges and let them hang out their respective holes until I unhooked them to disassemble (removed the individual gauges from the housing) and clean. If I used wd40 to clean all of the parts of the gauge and then put it back together could that cause the cvr to short??

 

[gride7]

So I disassembled the gauge again and checked to make sure it wasn't touching the housing by insulating with some electrical tape and this still did not work. My only guess is that for some reason the voltage regulator on the back of the gauge went bad.

I ordered another used gauge that has the voltage regulator to test it and see. Got my fingers crossed unless someone knows what the issue is out there.........

g