Still no water gauge temperature

[chopthebass]

Sorry to bug the forum with this but I am at a loss to know what to do.

I can't get my gauge to read water temperature. I even spoke to Speedhut and they gave me some tests to do. This is what I have checked:

Cable continuity - all ok
Sender resistance - measured 4.8k-ohms cold and dropped rapidly in boiling water
Joined sender cable terminals - gauge jumped to maximum
Checked continuity of ground at gauge between black wire and yellow/black wire
Checked voltage across gauge wires as suggested by Speedhut - measured 5v as it should.
Checked I have 12v at the red wire going to gauge

So everything checks out. I really hope it is something simple because I don't know what to check now. Help desperately wanted!

[rmiller64]

Is your Battery ground connected to the frame and from Frame to the Engine block?

[karlos]

Since you seemed to have ruled out most everything else, I'm wondering if you may simply have an air pocket behind the gauge sender. Noticed in the other thread you indicated the sender for the ECU is working properly. Since the ECU sender is working, I'd be inclined to temporarily swap the sender positions to see if it makes a difference.

Hope you find the solution. Frustrating when everything checks out but still doesn't work properly!

[j.miller]

How long did you run the engine. Sometimes it takes 8-10 mins to open the thermostat so it can read the temp.

[chopthebass]

I have battery grounded to chassis and engine has ground strap to chassis too.

I put the tip of the sender in a bowl of boiling water for 10 minutes. That should register on the gauge should it not?

[rmiller64]

I have battery grounded to chassis and engine has ground strap to chassis too.

I put the tip of the sender in a bowl of boiling water for 10 minutes. That should register on the gauge should it not?

No because you have lost the ground once you remove it from engine. If you connect the threads of the sender to battery ground while you put the tip in boiling water then it would work.


Or like Jeff Miller said let the engine warm up for 10 min it should register on guage

Hope this solves the mystery

[Scud67]

When installed, did you use a tape or heavy sealer on the threads? This could cause the sending unit to not be grounded.

[j.miller]

If it has two wires to the sender, then ,yes it should read in boiling water. If it's got one wire it needs the engine for a ground .Or a ground to the body of the sender to read in boiling water.

[chopthebass]

It has two wires and it gets its ground from the black wire. This connects to the yellow/black wire on the gauge, which has continuity with the black wire also in the gauge (going to ground). It's all very weird. I will be speaking to Speedhut again today.

[first time builder]

If you have power to gauge and the wire from the sender is showing continuity and the sender is good. I suspect a defective gauge. I have a set of inexpensive gauges I keep around for testing. You can buy a cheap temp gauge to try before removing the one from the car. Its easier. HF has a set of cheap gauges for under 20 $. I don't believe in putting a "T" with two temp sensors on it as I fell the water needs to flow completely over the sender and not get trapped. The "T" is also a place for air to get trapped.

[chopthebass]

Thanks FTB. The gauge displays maximum temp if I join the sender wires. This is a test Speedhut asked me to do. My problem has to be the sender, even though it decreases resistance in boiling water.

[Avalanche325]

The gauge displays maximum temp if I join the sender wires.

That tells me that you have a bad sender.

[acth4347]

The gauge needs to see a variable resistance to ground as the temperature changes. The sensor should read a higher resistance cold, lower resistance hot. What is the specific range for your gauge? Is it the right one for the Speedhut?
Do you have one side of your sensor grounded and the other side connected to the sensor terminal of the gauge? Did this work before or is this a new install? Generally speaking, this image shows how it should be connected. HTH, Bill
50096

[oldguy668]

The image above is incorrect for the gauges he has. His gauges have a two-conductor cable that connects the sender with the gauge. His gauge/sender combination should work even if the sender is removed from the engine or if there's a ton of thread tape on it. What the OP should do is power the gauge, put the sender in a container of water with a mechanical thermometer, and heat the container from room temp to about 200F. The Speedhut gauge should move right up the scale with the temp. If not, I would send the gauge and the sender back for repair.

[Scud67]

Sorry, didn't realize that he had a two wire sending unit. I was thinking of a one wire unit.

[chopthebass]

Thanks guys.

Avalanche, joining the sender wires is a test for the gauge. It should display max temp.

Anyway, I spoke to Speedhut and the resistance on the sender should be 700 - 900ohm cold, and 70ohm boiling. I get 5.2k and 441 ohms. I think I have the wrong sender.