HELP! Temperature Sender

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Dec 1, 2012 | 07:49 PM

Tony Rags

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HELP! Temperature Sender

Almost ready to pull my hair out...
1978 C3: just put a new temperature gauge in from Ecklers. I also put in a new "matching" sender from Eckler's. My electric fans turn on at 205 degrees. However, when the car is fully warmed up as evidenced by the fans turning on and off, the gauge never goes past the first mark (150 degrees). Sooooo, I changed the sender to a BWD (Borg Warner) WT-203 after reading that the resistance in that particular sender is more in line with what our gauges require to read accurately. After putting that sender in, the gauge reads in the red (240 - 280 degrees) when the car is warmed up. I went from one extreme to the other. I tested the gauge as per Wilcox directions and there's no issue with the gauge.
How do I get an "accurate" sender that will transmit the correct signal? Should I just try different manufacturers with trial and error until I find a sender that works right? What's the trick here? Thanks.

Dec 1, 2012 | 08:08 PM

Lil" Red Corvette

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Where are the senders that control your fans and where is the one that is for your gauge?

Dec 1, 2012 | 08:17 PM

Tony Rags

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The sender for the gauge is located in the thermostat housing (thermostat has bypass holes drills), and the sensor for the fans is right next to it in the front of the manifold (runs through a fuel injection system ECM).

Dec 1, 2012 | 08:51 PM

speedreed8

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originally, sender unit was installed in drivers side head between cyls. 1 & 3.

Dec 2, 2012 | 11:02 AM

Tony Rags

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Shouldn't make a difference between the head and thermostat housing locations. In any event, it still doesn't explain the vast difference between the 2 senders.
How do I get an accurate sender? What gives?

Dec 2, 2012 | 09:33 PM

Tony Rags

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Anyone know the difference between a WT203 and WT203Z? I'm at my wits end just trying different senders till I get it right....

Dec 3, 2012 | 08:33 AM

SteveG75

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From: FL

You need to calibrate the sender to the gauge.

Here is some good information.
http://forums.corvetteforum.com/c3-t...and-check.html
http://forums.corvetteforum.com/c3-t...e-success.html

Dec 3, 2012 | 12:01 PM

jnb5101

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From: charlotte north carolina

the bwd sender is causing a higher voltage drop across the meter resistor than the sender (the meter reads high voltage). go to radio shack and buy a 5 and 10 ohm 2 watt resistor (about a dollar each and a couple alligator test leads). get the engine hot and disconnect the sender wire from the sensor. connect the 5 ohm resistor in line (in series)with the sender wire and check the meter. if it's ok, splice the resistor into place permanently. if the meter still reads high use the 10 ohm resistor. if its still high, wire both the resistors end to end(series). if the meter reads too low, try wiring both resistors side by side (parallel). it's not going to be 100% accurate, but you don't have to pull the instrument cluster.