Temp sensor not working... - Corvette Forum : DigitalCorvettes.com Corvette Forums

graphicjunki · 12-16-2012, 02:26 PM

So the temp sensor wasn't even hooked up when I got the car. I put the temp sensor in the thermostat housing. There was a wire with blade clip coming off the alternator harness that looked like it goes into the place on the side of the head where you can also install the sensor. I couldn't find anything in ANY of my manuals about this stuff.. WHAT THE HELL?!
At any rate, I assumed (I know...) that it was the correct wire so I spliced in a longer section and plumbed it into the sensor.

Went through the cam break in last night and was monitoring the oil pressure and temp sensor. Oil pressure was great, but the temp sensor never budged.

Am I hooking it to the proper wire? Or should I be looking for something else?

Thanks.

Still trying to get the wood to go down from the lope!!

Can't wait to get the bugs out and take it for a drive!

TimAT · 12-16-2012, 04:39 PM

THe wire coming out of the harness close to the alternator for the temp sensor should be green. Normal spot is between the spark plugs 1 and 3. With the key on, and the sensor wire disconnected the gauge should go full scale to the right. Ground the same wire and it should go full scale left. (below 0).
It may be an air bubble in the t'stat housing, or you have a sender for a light and need one for a gauge.

graphicjunki · 12-16-2012, 08:13 PM

Well...the wire is the right one. Thanks!
However... Nothing happens when I disconnect/connect it.
The sending unit is for a gauge not a switch, I just recently purchased it.

What is the max volts sent to the gauge at full temp? I was thinking about using the power probe to energize the circuit. But I dont want to unintentionally fry the gauge.

Sly Vette · 12-16-2012, 08:47 PM

Quote:

Originally Posted by graphicjunki

Well...the wire is the right one. Thanks!
However... Nothing happens when I disconnect/connect it.
The sending unit is for a gauge not a switch, I just recently purchased it.

What is the max volts sent to the gauge at full temp? I was thinking about using the power probe to energize the circuit. But I dont want to unintentionally fry the gauge.

The sender does not send voltage in the normal sense. It sends a certain amount of resistance depending on the temp. from 0 to 90 ohms.
If you used teflon tape as a thread sealer the sender may not be getting an adequate ground. Other that that I would say you have an break in the sending unit wire or possibly a bad gauge. If you go to Wilcox site they have a great tech. section that will help you determine your problem.

graphicjunki · 12-16-2012, 08:53 PM

I am using teflon, but the wire fails the test either way. So there is something going on there. I need to figure that out and remove it from the equation.

So no teflon tape? <gasp!>

Thanks.

TimAT · 12-16-2012, 09:05 PM

The gauge "sees" resistance from the sender. 0-90 ohms. 90 ohms is full scale- whatever the "redline" on the gauge is. 12v testlight? Quick test. Get a good ground on the testlight clip, then probe the wire to the temp gauge. Key on, the bulb should glow- not full bright at all. With that bulb just glowing, the gauge should read about 1/2 scale. (bulb resistance is normally about 45 ohms).
This one, as good and handy as a powerprobe is, I've never tried to test a gauge with one.
I've used a testlight to check temp, oil pressure and fuel level for years- learned that trick when I was wrenching in the dealers working flat rate.

A thought-- is the oil pressure mechanical or electric? If it's mechanical, maybe check the gauges fuse.

Sly Vette · 12-16-2012, 09:10 PM

I have used teflon tape in the past without a problem but the last sender I installed I used nothing and there was no leak so I doubt I will ever use it in the future fir this application anyway.
If it were me the first thing I would do is try to test the length of the wire from the sender to the gauge or use a jumper to eliminate a bad wire as the problem.
Maybe with the wire grounded,probe with a test light at the bulkhead connector. If it lights you know the wire is good to there and the problem is in the interior.... then fun really starts.
Of course first determine that the sender is grounded properly. You can use the test light for that also.

graphicjunki · 12-16-2012, 09:44 PM

Great ideas guys. Thanks. I will try those next.

Thanks!

graphicjunki · 12-26-2012, 07:58 AM

I double checked with the part number I bought that my sensor was for a gauge and not a light. Good to go there...

I wasn't able to get any kind of reading for resistance on the sensor, but wasn't sure I was doing it right. I removed the Teflon tape, and reseated the sensor. Started the car and let it run until the upper and lower radiator hoses were both hot. Checked the gauge...Nothing.
I tested for continuity between the sensor and the housing...barely, but it was there.
Broke out the power probe and applied ground to the sensor wire. Gauge pegged to the hot side. So I know that the gauge is good, as well as all wiring from the gauge to the sensor.

I guess that tells me that the sensor is bad.

But on a positive note, I got to drive the car on Christmas Eve day.

Wife asked me to deliver some goodies to some friends a few blocks away. I knew that I COULDN'T over heat it IF there was any issues with the coolant, so I fired it up and took it out.

Two things became quickly apparent...
1) Timing isn't dialed in still
2) GOTTA get this thing to Lars to rebuild the Qjet!

And I think that the gas is getting old. Good thing it's almost on E. Time to fill it up with some good stuff!

Ooooohh...and a side story. My father in law is in town. He wanted to help me work on the vette. So before the mentioned drive, we installed the side pipes. They were only mocked up prior to this. When he went to get in the car, the door scraped on the pipe. So to 'adjust it', he STEPPED on the pipe to bend the bracket down. I LOST IT! First time in 20 years of knowing him, I've ever yelled at him. LOL! Don't think he know how to deal with that!

AirbornSilva · 12-26-2012, 11:59 AM

Hmm, I think I put teflon tape on mine when I put my new engine in, I think I'm going to have to check that since my gauge isn't reading right.

graphicjunki · 12-26-2012, 12:25 PM

It's mentioned here not to, as well as I found on either Ecklers or Corvette America when trying to find the right part #, it was listed straight in the description NOT to seal.

TimAT · 12-26-2012, 12:28 PM

Apologize to your father in law-- that's how to adjust the height of the sidepipes. With the bolts installed correctly- in the center of the frame holes, with the rubber bushings in place and everything tight, that's the only way I've ever found. The brackets get bent a little in shipping or not angled correctly, the pipe needs to roll a little-

graphicjunki · 12-26-2012, 01:03 PM

Ummm no. Right or wrong method...

I would NEVER just stomp on someone else's project, unless it was talked about and agreed on first. I'm meticulous about things like this and he knows it. I would first try and loosen the brackets and move it, AND try to measure it in the process so as to ensure that they are symmetrical. NOT jump up and down on the damn thing and take a chance of messing up the shape of the pipe. What if the opening got crushed, instead of the bracket bending as you would think? That would never look the same again. That's just me.

There's no bad blood between us. He understands my frustration. And we are still good buddies. No worries. It did shock him, but all well.

TimAT · 12-26-2012, 05:52 PM

MY apologies.. I figured you'd tossed him out from your post. I've tried adjusting the pipes by moving the attach bolts, Didn't work for me. I ended up with a 2x4 stuck in the end of the pipe and leaning on it to bend the brackets. That's how the first set got adjusted. Since then, it's the foot on the pipe and bounce a little.