1956 Temp Gauge problems

[lts70]

It has always had problems pegging out hot after you drive it for awhile, even though it is not hot. I have double checked it with my heat gun and it runs cool.

I put an all new AutoWire wire kit in so the wiring is new. And I put a brand new temp sensor in the manifold as well as new thermostat.

Is there a way to test the gauge? Or anything I may be overlooking?

[hyatt]

make sure temp sensor is for a guage not a light Light sensor will do just what you decribe

[lts70]

It was a NAPA Part# TS6469


Part Number: ECH TS6469

Product Line: Echlin Ignition Parts

Attributes:
# Switch Terminals : 1

Temp Sender Switch Temp Rating : 72-88 Ohms Resistance At 220 Deg F

Temperature Switch Thread Size : 1/2" x 14 NPT

Warranty:36 Months or 36,000 Miles Whichever Occurs First

[Russell Ashley]

Originally Posted by lts70

It was a NAPA Part# TS6469


Part Number: ECH TS6469

Product Line: Echlin Ignition Parts

Attributes:
# Switch Terminals : 1

Temp Sender Switch Temp Rating : 72-88 Ohms Resistance At 220 Deg F

Temperature Switch Thread Size : 1/2" x 14 NPT

Warranty:36 Months or 36,000 Miles Whichever Occurs First

That's the same sender I'm using and it works correctly with my stock 57 gauge. Mine is in the driver side head near the front.

[mark '87 930]

I had similar problems with mine and bought the right sensor as well. I questioned that for some time, but just last winter when i rewired the truck, I found that my temperature gauge itself was loose. The probes that stick out behind the gauge needed to be tightened down.

Now my gauge works perfectly.

[1project2many]

Older engines often had lower resistance range for "hot" than current engines and using 190 T-stat causes high readings. If sensor is correct and resistance matches gauge requirements, it's ok to add a resistor inline to bring the temp range a bit lower.

[butchp]

Mine is doing the same thing, after i installed a t stat 160. If I reach under dash and remove the closes wire and reinstall it the gage reads correct. I also put brushes in gen and it is worse when the gen is full charging. I can see the greater charge in the temp gage. From what one person said it could be a ground problem.

[Highsider]

Originally Posted by butchp

Mine is doing the same thing, after i installed a t stat 160. If I reach under dash and remove the closes wire and reinstall it the gage reads correct. I also put brushes in gen and it is worse when the gen is full charging. I can see the greater charge in the temp gage. From what one person said it could be a ground problem.

Sounds weird enough, that it must be a ground as you said.
Love to hear how you fix it.

[solidaxel]

Originally Posted by 1project2many

Older engines often had lower resistance range for "hot" than current engines and using 190 T-stat causes high readings. If sensor is correct and resistance matches gauge requirements, it's ok to add a resistor inline to bring the temp range a bit lower.

A variable resistor to tune the gauge with a IR gun!!

[1project2many]

I spent a ton of time looking for proper calibration values to check my gauge and get the sender right when I put my truck together in the '90s but I have no idea what reference I used at teh time. I used a DR134A sender which crosses to a NAPA TS6469SB. That sender fits a million vehicles so I searched the net and found this applicable chart:

[quote]Heres some resistance values for three senders 6 dollar TU5 Wells sender from Autozone, 25 dollar "correctly calibrated" Lectric Limited model 01513321, and an original GM 1513321 sender (for a Pontiac Firebird - one with the slide on connector- Camaros use a 1513462 with a screw on lug).

80 degrees: Wells at 650 ohms, LL at 573 ohms, GM at 549
90 degrees: Wells at 526 ohms, LL at 445 ohms, GM at 524
100 degrees: Wells at 429 ohms, LL at 365 ohms, GM at 409
110 degrees: Wells at 328 ohms, LL at 266 ohms, GM at 365
120 degrees: Wells at 283 ohms, LL at 227 ohms, GM at 323
130 degrees: Wells at 250 ohms, LL at 200 ohms, GM at 272
140 degrees: Wells at 216 ohms, LL at 170 ohms, GM at 227
150 degrees: Wells at 198 ohms, LL at 155 ohms, GM at 195
160 degrees: Wells at 173 ohms, LL at 133 ohms, GM at 175
170 degrees: Wells at 157 ohms, LL at 119 ohms, GM at 157
180 degrees: Wells at 135 ohms, LL at 101 ohms, GM at 140
190 degrees: Wells at 120 ohms, LL at 89 ohms, GM at 125
200 degrees: Wells at 109 ohms, LL at 79 ohms, GM at 109
212 degrees: Wells at 104 ohms, LL at 75 ohms, GM at 102
[quote]

A variable resistor to tune the gauge with a IR gun!!

Good idea. Get a 100 Ohm version in "linear potentiometer" rather than a "logarithmic potentiometer". It looks like 15 to 30 Ohms can be added in series to put the gauge at about the right point. Of course this assumes the wires are good, power is good, and the gauge and sender work correctly.