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Go read the Willcox troubleshooting procedure to ascertain whether you have a bad sensor, a bad gauge, or a bad conductor.....anyway, if they're all ok, then.....
But FIRST--- why did you relocate the sender? I relocated mine because my Vortec heads have too small of a hole for my 68 sender.
You want to make sure that you have a good ground from your intake manifold to the chassis also (intake, to block, to chassis, typically just bolting down the intake manifold should take care of this..
Don't use sealant on the temp sensor either. I just use nickel anti-seize and haven't had any leaks for ages.....you want good continuity between the sensor and the manifold.
After you do those 2 checks, if your gauge still reads improperly, then get the Willcox adjustable resistor... hell, get it anyway, it's fantastic and you can dial your gauge in beautifully. That first unlabeled increment is about 180°F so be aware of that.
Originally Posted by titanle
How does the resistor fix the problem? With a temp gun at various parts of the motor it reads 180 but on the gauge it’s always full.
Keep in mind the actual temperature will be different depending on where you read it on the engine. The stock location for the temp sensor on big blocks is in the cylinder head on the driver side, which is probably the hottest place on the entire engine. Relocating the sensor to a place on the intake manifold or thermostat housing where the engine coolant has mixed will give a different reading. Decide what is a normal reading for your engine based on the location of the sensor. Check with a temp gun if you feel a need to confirm the reading on the temp gauge.
The temp sensor was located due to the new heads and intake. I do recall before it was on the driver side and now it’s on the top near the thermostat. My mechanic did tell me why it was moved but now I can’t seem to remember.
There is is some sort of sealant around the sensor as the photo shows. I wonder if that’s the culprit.
I will buy the resistor to see if it remedies the problem. I still have to check to see if anything else is malfunctioning.
Temperature will be pretty close. Since you have temp gun you can determine the temp and then adjust the resistor to have the gauge match the temp gun reading. BUT FIRST do the troubleshooting per the Willcox website. You're going to love having a gauge that reads properly
Originally Posted by titanle
The temp sensor was located due to the new heads and intake. I do recall before it was on the driver side and now it’s on the top near the thermostat. My mechanic did tell me why it was moved but now I can’t seem to remember.
There is is some sort of sealant around the sensor as the photo shows. I wonder if that’s the culprit.
I will buy the resistor to see if it remedies the problem. I still have to check to see if anything else is malfunctioning.
H-m-m-m-m. Reminds me of the guy who put so much thread sealant on a block / intake / head type sensor that the unit could not possibly ground itself. So gauge always reads high.
Last edited by HeadsU.P.; Jul 6, 2019 at 10:30 AM.
From: Some days your the dog and some days your the hydrant.
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With a multi-meter, put one lead on the block and the other on the temp sender casing and measure resistance. If reading is zero, the sensor is grounded properly. Also, it doesn't matter whether the sensor is in the block or in the intake. The coolant temperature will be the same. And don't put much faith in readings from a $20 temperature gun to calibrate a temp gauge.
It does look like a boat load of sealant/tape or whatever was used to seal it. I guess a logical first step would be to clean all that out and see if I get a proper reading before attempting the other troubleshooting tips listed above.
2020 Corvette of the Year Finalist (performance mods)
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If you dont use a 68 sender for a 68 gauge its not going to read correctly. If you use a 80 or newer that fits the smaller holes it will read incorrectly. ITs not the same nonlinear resistance scale. I went through this same problem and bought the correct one from Willcox that was turned down to fit my new aluminum heads. Your paying for the sender , then the labor to pull it apart, turn it down, then rebuild it. It works great.
If you dont use a 68 sender for a 68 gauge its not going to read correctly. If you use a 80 or newer that fits the smaller holes it will read incorrectly. ITs not the same nonlinear resistance scale. I went through this same problem and bought the correct one from Willcox that was turned down to fit my new aluminum heads. Your paying for the sender , then the labor to pull it apart, turn it down, then rebuild it. It works great.
Thats an issue for me because this car is a whole mishmash of parts so I have no idea what’s actually 68 and what’s been changed. I’m guessing it’s a 68 gauge because they all look old and dated and they were in the stock 68 bezel.
Beyond that it’s hard to tell what’s been changed.
What do you mean by turned down? Pardon my ignorance.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I blieve the thread size is 1/2inch NPT (national pipe thread) which is almost 3/4 inch across. And the hole I have in my heads is 3/8inch NPT so he puts it in a lathe and turns the thread size down to fit. measure your openning for a best guess. I/2 inch is close to 3/8NPT
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Originally Posted by titanle
Thats an issue for me because this car is a whole mishmash of parts so I have no idea what’s actually 68 and what’s been changed. I’m guessing it’s a 68 gauge because they all look old and dated and they were in the stock 68 bezel.
Beyond that it’s hard to tell what’s been changed.
What do you mean by turned down? Pardon my ignorance.
some intakes you have plenty of meat to cut a larger pipe thread where the sender location is. you gotta remember pipe sizes are the size of the hole in the pipe the stuff flows through. 1/8th pipe is close to 3/8 fine thread, 3/8th is a little bigger than half, etc. does the temp read above 210 degrees? do you hear boiling water bubbles as soon as you shut it off? if not, then gauge is reading high.
Dude, you're overcomplicating this. I have a 68 sender in the intake manifold.
Do the Willcox checkups for the gauge, wiring, and sender..... and if they all appear satisfactory, AND you have good contact with installation, then just get the Willcox adjustable resistor and dial it in.
Originally Posted by titanle
Oh okay I understand what you mean. The intake is an edelbrock torker. I’ll google the specs to see what size is required.
Temp sensor for edelbrock intake
