Need help with water temperature gauge

[RockBit]

I have not been able to get my water temperature gauge to work and was wondering if anyone can help me.

I have the electronic version of the Smith gauge. When I turn on the ignition switch, it sweeps to the right and returns. The light in the gauge also works when the headlights are on.

There are four wires coming out of the gauge. Here is what they are connected to:

R/W wire from gauge is connected to number 5 red on the harness.

G wire on gauge is connected to the thin geen wire on the harness, which I thinks is the power for the dash lights.

B wire on the gauge is connected to the number 5 black on the harness.

B/W wire on the gage is connected to the sending unit on the intake manifold.

If I start the car and let it warm up, the water temp gauge never moves from cold. Any idea what I am doing wrong?

Thanks.

[DanEC]

Call Doug at ERA - surest means of a quick, correct response. I suspect most owners have the mech gage. An air bubble is one possibility.

[RockBit]

Dan:

I will call Doug next but I was hoping someone would get me going this weekend.

Thanks,

[dacobb]

Originally Posted by RockBit

Dan:

I will call Doug next but I was hoping someone would get me going this weekend.

Thanks,

Sounds like you have a helluva cooling system.

Specs?

[jhv48]

Did you recently replace the gauge and sending unit or is this a problem that just cropped up? Possibly a dumb question, but if you did replace the gauge,did you pair up the electronic gauge with the correct sending unit? If so, then you might have a faulty sending unit.
When I wired mine, I ran the hot lead to a switched terminal on the fuse box, the ground wire to a grounded bolt, the lead wire to the sending unit and the last wire is connected to the dash lights.
The sending unit could also be sitting in/surrounded by an air bubble as mentioned. With the engine running, slowly loosen the sending unit a little until coolant runs out, then tighten it back up. That will ensure there is no air caught in the passage. If still no reading, call Nisonger and replace the sending unit.

[patrickt]

And if you have the Smiths BT2240-00C I'm pretty sure it has to be fed by a voltage stabilizer. So, that means one of the feeds is going to have to be the regulated ten volts (not twelve), another lead is going to be your ground, a third lead will be the 12v rheostat controlled feed for the lights. And then there's the feed to the sender. What I would first do is put a VOM on the wires and see if one of them was feeding me ten volts when I know the battery is 12.6 volts. Then I would disconnect the wire at the sender on the intake manifold and run a direct wire from the sending unit up over the windshield and in to the cockpit and see if I could get the gauge to respond using that 10v feed and the short cut wire to the sending unit (with the engine hot, of course). If you can, and you have the lights already working, then I would trace the leftover wires in the harness to see which one connects up to the sender, since I can make it work with the shortcut wire. Maybe the whole problem is there is no connection between the sender and the gauge. But, I have all mechanical Smiths gauges... they're pretty easy to wire up.

[RockBit]

Originally Posted by jhv48

Did you recently replace the gauge and sending unit or is this a problem that just cropped up? Possibly a dumb question, but if you did replace the gauge,did you pair up the electronic gauge with the correct sending unit? If so, then you might have a faulty sending unit.
When I wired mine, I ran the hot lead to a switched terminal on the fuse box, the ground wire to a grounded bolt, the lead wire to the sending unit and the last wire is connected to the dash lights.
The sending unit could also be sitting in/surrounded by an air bubble as mentioned. With the engine running, slowly loosen the sending unit a little until coolant runs out, then tighten it back up. That will ensure there is no air caught in the passage. If still no reading, call Nisonger and replace the sending unit.

Everything is new and supplied by ERA with the car. I checked to make sure the thread compound I used on the sending unit is conductive. I will try to burp the system as you suggest to be sure there is no air pocket. Thanks for the tip.

[66AC]

I would get some very hot water (previously boiling) in a small pot, and immerse the sending unit into the hot water with the ignition of the car ON but not running to test the sending unit. This of course assumes all your electrical connections are correct and good.

Also, there probably is a way to read the impedance coming from the sending unit with a multi-meter. Perhaps you can find information on that from Smiths or the web? I have SW gauges and there is published data for SW's water temp gauge as I recall.

[RockBit]

I got back from my trip late last night and tried to reach Doug today but he was out. I'll call him in the morning. I spent some time searching the net and reading today. I think Patrick is correct. Everything says that these Smith's electronic gauges must be supplied by a stabilized 10V source. This includes the fuel gauge, and both oil and water temp gauges. These are the three I am having trouble with. Hmmm.

I'll let everyone know what Doug says tomorrow.

[patrickt]

Originally Posted by RockBit

I think Patrick is correct.

You think?

[RockBit]

I talked to Doug this morning. He has built cars with the same gauges I have and did not use a 10V power converter, he just hooked them up the regular way and everything worked fine. Doug said to ground the sensor wire and see if the gauge pegs, which I had already done (and it pegged). This indicates the gauge is working ok.

Doug advised that I need to let it run for 15 minutes before I will see any indication of temperature on the gauge. He also said that since I have a heater in the car there will no be an air pocket around the sensor.

I will start and run the car longer and see what happens. I have a laser thermometer that I can check the temperature with as it warms up. I'll report back after I do all this.

[Bartruff1]

I have zero confidence in any gage I have ever had in a component car....

[RockBit]

Well, I need to go with what I have.

Patrick will be interested in knowing I have ordered a 10v stabilizer. The Smith-UK website is pretty convincing.

[spdbrake]

This handy guide may help in your T/S. I'm doubting you'll be needing the stabilizer

Smiths Voltage Stabilizers - REVISED

[patrickt]

Originally Posted by spdbrake

This handy guide may help in your T/S. I'm doubting you'll be needing the stabilizer

Smiths Voltage Stabilizers - REVISED

That's a great doc for troubleshooting the electric Smiths gauges. I don't know if you absolutely have to have the stabilizer or not. Doug is usually about 99.9% correct on stuff like that. But, if it was me, I'd pull the gauge out of the dash, pull the sender out of the manifold, and put it all on my work bench, along with the stabilizer, and work with it, along with a little 12v transformer feeding the stabilizer, until I had the gauge working when the sender was sitting in a cup of boiled water.

[RockBit]

Another gauge problem I have is the voltmeter. It has never moved since I installed it in the car. I pulled it out and put 12 volts across it on the bench. Dead as a door nail. I'm going to test all the non working gauges before I put the dash back in.

[RockBit]

I got the 10V converter today. Hooked it up to a 13V source and got 9.98V out. Good to go.

I pulled the water temp gauge and sensor out of the car. Applied 10V to it with the sensor in boiling water. The needle never moved. I then retested it with 12V. Needle never moved. I think the sensor is bad. The gauge does a full swing when initially hooked up.

Tomorrow I will do the bench test on the oil temp gauge and sensor.

[Gaz64]

Originally Posted by RockBit

I got the 10V converter today. Hooked it up to a 13V source and got 9.98V out. Good to go.

I pulled the water temp gauge and sensor out of the car. Applied 10V to it with the sensor in boiling water. The needle never moved. I then retested it with 12V. Needle never moved. I think the sensor is bad. The gauge does a full swing when initially hooked up.

Tomorrow I will do the bench test on the oil temp gauge and sensor.

Did you have the sender case grounded to your negative supply with an alligator clip?

Is this a single wire sender, or two wire sensor?

Electronic or electric gauge?

[RockBit]

I forgot to ground the sensor case. Duh. I will do the test again tomorrow. It is a single wire sensor and the gauge is a Smith's electronic.

Thanks Gaz!

[Gaz64]

You'll always remember to do this as a test now Chris.

Best of luck for tomorrow.

Gary