Author Topic: Temperature sending unit and proper gauge readings. What is correct?  (Read 1453 times)

sdkar

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Hey guys,

How can I tell which sending unit is the proper one to buy for a 69 Camaro with gauges?  They all look the same, so how can I check to see if the one I have in my car is correct and/or working properly.  My temp gauge reads just above the left after it is fully warmed up, so I am not sure it is working properly.  Where should the gauge be reading when the engine is running at around 180-200 degrees?

Thanks,

Steve

big iron

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Re: Temperature sending unit and proper gauge readings. What is correct?
« Reply #1 on: February 26, 2012, 11:35:20 PM »
I believe the 69 w/ gauges is the only sensor with a threaded stud.
Bob

Mike S

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Re: Temperature sending unit and proper gauge readings. What is correct?
« Reply #2 on: February 26, 2012, 11:39:09 PM »
 My 67 reads about mid scale when at normal operating temperature.

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

Mark

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Re: Temperature sending unit and proper gauge readings. What is correct?
« Reply #3 on: February 27, 2012, 01:42:13 AM »
Most 68/69s run 1 tick above 1/4 scale at 180 degrees.
Mark C.
1969 Indy Pace Car
350/300HP RPO Z11

sdkar

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Re: Temperature sending unit and proper gauge readings. What is correct?
« Reply #4 on: February 27, 2012, 06:17:55 AM »
I have several temp sending units laying about.  Any way to tell if they will work or not?  There are some numbers on the hex points...do these mean anything?  Is there a way to put them on a tester to see if they will still work and if so, what are the readings I should be looking for?

Thanks.

JohnZ

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Re: Temperature sending unit and proper gauge readings. What is correct?
« Reply #5 on: February 27, 2012, 04:58:59 PM »
<<I have several temp sending units laying about.  Any way to tell if they will work or not?  There are some numbers on the hex points...do these mean anything?  Is there a way to put them on a tester to see if they will still work and if so, what are the readings I should be looking for? >>

Photos below show the configuration and part numbers for original temp gauge senders, and a chart showing the resistance/temperature profile they produce between the wire terminal and the sender body.
'69 Z/28
Fathom Green
CRG

Mark

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Re: Temperature sending unit and proper gauge readings. What is correct?
« Reply #6 on: February 27, 2012, 06:35:42 PM »
Gauge normally reads 1 tick above 1/4 scale with the engine operating around 180 degrees, thats just how the originals work.

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

If you have a gauge with an external resistor you can change it from the stock 86 ihm resistor to a 91 ohm resistor and that will move the gauge up to 1 tick below half, at 180 degrees. I've done that, I use a potentiometer with two short leads on it, I adjust it to what i want the gauge to read and then lock it down in a ball of electrical tape so it can't change. If your gauge has the resistor built into it, then you have to live with it reading low, or get a sender that has a lower resistance at each of the temps above.
Mark C.
1969 Indy Pace Car
350/300HP RPO Z11