Engine Temperature and gages. Update

[Tom Bredehoft]

[buddymander]

I think you're just bragging...and I can't say I blame ya. My car is 12 volts and I can't seem to get my temp gauge and fuel gauge working...

[Tom Bredehoft]

The fuel gage is coming around, not yet, though. Yeah, I guess I'm braggin'.

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Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
....On the road, again....
'05 Legacy Ltd Wagon
All Indiana built cars

[zoegrant]

I have the same problem...converted to 12 volts but have no fuel or temp guage ...the temp guage will slowly rise after about two miles of driving and finally peg itself at full hot....I tried grounding the wire from the RUNTZ votage drop but to no avail...still pegs hot and I know I have no over heating issues...triple checked the fuel sender, not that so I dont know what it is...all ideas are welcome....John

[Tom Bredehoft]

I've been playing with the temperature gage, and various resistances between the sender and the gage.

To make a long story short, I have now installed 60 Ohms resistance between the sender and the gage. the needle comes up to the left end of the center bar when cold, a reading of about 140 deg, with the engine (and the rest of the car) at 60 deg ambient. With the engine at running temperature, (a measured 165 deg) the needle is one needle width short of the right end of the bar, or about 175 deg. I'm concerned that if I ad any more resistance, there won't be enough movement in the needle to register an overheat situation.

The fuel gage, (I got a 0-90 Ohm resistance sender from Summit Racing that bolted in (after I bent the arm judiciously) The fuel gage works fine, except backwards. I can get used to that.

CASO lives. Even if this were a show car, no judge would find fault with my solutions.

[Edit] typo

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Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
....On the road, again....
'05 Legacy Ltd Wagon
All Indiana built cars

[gordr]

Tom adding a fixed resistance in the line to the sending unit will not help the range of the gauge. Sounds like you need a new sending unit.

I believe others have simply used NOS Lark-type gauge units inside the '55 housing to convert to 12 volts. Perhaps someone who has done this can comment.

One thing you could do: obtain a potentiometer (or rheostat), range 0-500 ohms. Substitute it for both the fuel and temp sending units, in turn of course, not together. Make sure you start with it set at its 500 ohm position. Slowly tweak the knob until the gauge in question just comes off the zero peg. Wait a full minute after each "tweak" since thermo gauges are slow to react (feature, not a bug). When you identify the point in the pot's travel that JUST gets the needle off the zero peg, take the pot out of circuit, and measure its value with a good multimeter. Write down your results. Repeat the exercise at 1/4, 1/2, 3/4, and Full(Hot). You will now have a table that shows the resistance range required for the sending unit needed to work with each gauge. If what you get conflicts badly with the published ranges for sending units, suspect a bad gauge unit, or that an incorrect one has been installed.

Don't overlook the possibility that a mistake was made in wiring the dash units, and the terminals were connected wrong. That will make the gauges peg out very early.

Gord Richmond, within Weasel range of the Alberta Badlands