digital water temp goes nuts

[earthman]

I thought it would be clever to use a digital cooking probe inserted in the water neck of the model a. It had its own AAA battery and was separate from the A's electrical system. Worked fine until i turned the motor on then the readout went nuts and never recovered. Now i have a digital Cyberdyne temp gauge. The sender is in the same place in the water neck and even if i connect the gauge directly to the battery it goes nuts until i turn off the engine. It's just a simple model a, no radioactive magnetic fields or high teck electronics in the system. If i can't cure this it will be another $50 for a mechanical gauge. Any one have any experience with this?

 

[CR55]

I'm not certain, but could it be the sending unit? I know how you feel about just buying new parts and hoping that sooner or later you'll figure it out. Gets expensive!....CR

 

[shortyforty]

Are you running a 6 volt battery and is the digital gauge a 12 volt?

 

[earthman]

CR55,that is one probe and one new sending unit, same results with both.
Thanks for the reply.

 

[earthman]

Shorty,it is converted to 12 V. It isn't vibration either. I could hold the gauges
in my hand with no change. Thanks for the reply.

 

[shortyforty]

if you are converted to 12 volts are you running a Generator or Atenator? Altenators can generate more electrical noise that might interfere. Or the electrical noise from the coil spark if you have a bad ground in the system. Also could just have a bad meter. Try it on another vehicle and see if you have the same issue.

 

[dogpatch1]

have you tested the coolant for electrolisis? are your grounds good? try a temporary ground on the radiator right to the engine and battery. it sounds funny but the coolant could be acting as a ground with variable resistance causing interference. dp1

 

[earthman]

Already been a month since i looked at this post! Thanks for the help everyone. I read the fine print on the instructions finally. The alt and plug wires are interfering with the gauge.

 

[Grumpyoldman]

What do you mean, finally read the instructions?

Real men don't need no stinkin' instructions....

Glad you figured it out...