85 Nissan 720 4x4 Temperature gauge.

[Thomas Perkins]

I just have bad luck with temperature gauges.A while back I replaced it cause one of the white wires was burnt up.I showed everyone here.But that was the last thing I checked.Should of checked it first,but no one does.But anyway,I did replaced everything connected to the reason why it was reading low,thermostat,sensor,sender,water pump,The temperature gauge has been reading low, a 1/4 up.I did put another temperature gauge in it back then but it never has read right.Recently I fixed a coolant leak,and drained the coolant out of the radiator.When I started it,to get air out with radiator cap off,the temp.gauge barely went up before the thermostat opened,and I got all the air out.So if it were to run hot I would never know by the gauge.So I just bought one from Ebay for 27.53.I will install it when it comes in.Buying used stuff is always a gamble,last temp.gauge came off a speedometer I bought from 720 World.

 

[Thomas Perkins]

So what does everybody think.Bad temperature gauge or something else.Lets see what everybody knows.Did I throw my money away?It only goes up the dial under 1/4.Remember everything else is new.Also they are almost or are 40 years old.

[Thomas Perkins]

Two things it could be.A loose temperature sender(thermal transmitter), electrical connection.A bad temperature gauge.It will go up to a third in the morning.Then after work it goes to a fourth up.It needs to.be in the middle when warmed up and thermostat should open right before it goes to the middle.Thermostat opens when,t is just over a eighth up.I will clean the fittings at the sender.And when I take the speedometer out

 

 

 

 

[Thomas Perkins]

My temperature gauge will be in the mail box today.Our mail comes in later part of the day.I will install it when I get off work tomorrow.It came from Oregon.Got here fast.

[powderfinger]

The temperature guage in my 4x4 has never read over 1/4 I don't think. The same engine and same thermostat in my old 2x4 truck read in the normal range. I just keep driving it :-). I figure if it ever goes higher than it is then it's starting to overheat lol. I guess it is possible the guage isn't capable of going any higher for whatever reason but seems unlikely, I think :-).

Edited November 2, 2023 by powderfinger

[Stoffregen Motorsports]

You can always play around with the resistance and zero in on the correct readings. I use a guitar amp volume knob to set the readings, and then once I have the reading correct, measure the resistance that the knob is set at, then solder in a resistor with the same ohms.

 

Or, you could try a different temp sender.

[Thomas Perkins]

Here it is.It is real.clean.I hope it works.It does have a return policy.

 

[Thomas Perkins]

Here is what the gauge was showing on the way home from work.It was half that when I burped it to get thermostat to open up to get air out.It use to go past half when the thermostat would open,then it would go to half way and stay there.The thermal trasmitter(temperature Sender) Fittings are clean.Getting a good connection.We will see.I was driving 65 when this picture was taken. Marshall Tucker Band was playing

Virginia.

 

 

Edited November 2, 2023 by Thomas Perkins

[powderfinger]

Your picture is what my 4x4 has always been at for some reason. I just keep driving it.

[datzenmike]

 

23 hours ago, powderfinger said:

The temperature guage in my 4x4 has never read over 1/4 I don't think. The same engine and same thermostat in my old 2x4 truck read in the normal range. I just keep driving it :-). I figure if it ever goes higher than it is then it's starting to overheat lol. I guess it is possible the guage isn't capable of going any higher for whatever reason but seems unlikely, I think 🙂.

 

 

 

You can test the gauge by grounding the sensor wire to the intake. The gauge should go all the way HOT. If it doesn't then the gauge is bad.

 

 

 

2 hours ago, powderfinger said:

Your picture is what my 4x4 has always been at for some reason. I just keep driving it.

 

If the gauge goes to full HOT I would change the thermostat. They don't last forever. If it's running that cool it will run better at halfway and give better mileage and performance.

[Thomas Perkins]

Here is my speedometer out of the dash with both temperatures gauges.Both look good.The one in it had a like new dial so.I swapped them.Dont see anything wrong with the one I am taking out.

[Thomas Perkins]

Today on the way home from Work.

[Thomas Perkins]

Mine use to run in the middle and you could see when the thermostat opened cause it would go a hair above half then drop to half and stay.Never had a thermostat go bad in 29 years.Usually changed them when a head gasket blew or new radiator or new water pump.Or changed coolant.If this does not changed it.Then screw it.ThermostatBut anyway  now opens a hair below a quarter.I guess if it were ever to run hot it will go up maybe 3/4's.That is what worries me.Happy Friday.

Edited November 3, 2023 by Thomas Perkins

[Thomas Perkins]

Time to put it back in.Check out my mileage.I have 106,000 on my Jasper Engine.Been a good one.

Edited November 3, 2023 by Thomas Perkins

[Thomas Perkins]

Here's my take on our Temperature gauges.I put both of my temperature gauges side by side.The one I just bought.The dial goes lower at the cold thick line mark than my other one.So it now goes lower when at its setting point when engine is running.So they need to be calibrated.The gauges have two lines at the H and C.The dial needs to be at the thin line at the cold when not running.So if it were to run hot it will never make it to the H mark.There is a little clip holding the dial on.What I need to do is remove the clip and set the dial at the thin line at C mark.Then it will.go half way up like it is suppose to when it is warmed up.It will be a job getting the clip off with out breaking the dial.I also had to calibrate the RPM dial.It moved to the 8000 rpm reading.I pushed it back to zero and it went below it.So I had to.push dial.bsck to 8000 and push it some more.Then turn back to zero and make sure it was dead on 0, you may have to keep.going to 8000 and pushing till.it is on O. It happened last time.Just remember the temperature gauge should read dead on the thin when cold/ or turned off.

[datzenmike]

Well the power supply is regulated at 7-8 volts for both the gas and temp gauges and they move through the same arc. The resistance of the gas sender in the tank is 37 ohms for a reading of half way on the gas gauge. It can be assumed that to read half way on the temperature gauge the temp sender should also be 37 ohms.

 

 

 

Should be easy enough to run till stabilized at running temperature(see above picture) then pull the sender wire off and connect a meter to the sender and  see what the resistance is. If 37 ohms then the gauge is at fault.

 

Looks like about 1/4 so if around 56 ohms then the gauge is ok and the thermostat is open too soon or doesn't close properly. Or the sender does not go above 56 ohms.

 

Borrow an IR gun and 'shoot' the thermostat cover to confirm 180-185F or is it cold?

[Stoffregen Motorsports]

21 hours ago, datzenmike said:

Well the power supply is regulated at 7-8 volts for both the gas and temp gauges and they move through the same arc. The resistance of the gas sender in the tank is 37 ohms for a reading of half way on the gas gauge. It can be assumed that to read half way on the temperature gauge the temp sender should also be 37 ohms.

 

 

 

Should be easy enough to run till stabilized at running temperature(see above picture) then pull the sender wire off and connect a meter to the sender and  see what the resistance is. If 37 ohms then the gauge is at fault.

 

Looks like about 1/4 so if around 56 ohms then the gauge is ok and the thermostat is open too soon or doesn't close properly. Or the sender does not go above 56 ohms.

 

Borrow an IR gun and 'shoot' the thermostat cover to confirm 180-185F or is it cold?

This is basically the same as the way I was explaining it, but I use the guitar amp volume knob.

[Thomas Perkins]

Here is the temperature gauge I took out.I have reached under the dial and pushed the metal piece that makes the dial move when coolant heat up.I have lined it up with the thin line at the C.So now I will take speedometer backout and remove the 27 dollar temperature gauge I just bought and install the one I took out at the beginning and see if it will read in the center of the gauge.If that works then I will recalibrate the other temperature gauge.

 

 

 

Edited November 5, 2023 by Thomas Perkins

[datzenmike]

 

On 11/2/2023 at 12:08 PM, Stoffregen Motorsports said:

You can always play around with the resistance and zero in on the correct readings. I use a guitar amp volume knob to set the readings, and then once I have the reading correct, measure the resistance that the knob is set at, then solder in a resistor with the same ohms.

 

Or, you could try a different temp sender.

 

Connect this variable resistance to the connected sender wire and the other end to ground. This will increase the current through the gauge and raise the needle higher across the board.

 

[Thomas Perkins]

Here is where I am at.I decided to use the one in there cause I don't want to swap the front plate out.I moved the dial on this too.At the thin white line by the C.Putting it back in now.I can take the speedometer out in 10 minutes.

[Thomas Perkins]

Here it is.

 

Edited November 5, 2023 by Thomas Perkins

[Thomas Perkins]

All put back together.I will check it out on the way to work in the morning.I may have to take it out and tweak it to get it just right.I love my things perfect.I will take a picture of it on the way home from work tomorrow.

[Stoffregen Motorsports]

On a recent build, I found that the thin stainless strip inside the gauge that controls the needle was bent, giving the oil pressure a low reading. I bent it into shape with a needle nose pliers, then cross checked it against a mechanical Stewart Warner gauge, and it was right on the money.

 

The point is, even if it weren't damaged, you can bend that strip to change the gauge reading.

[Thomas Perkins]

It is fixed.I also have a extra one.

Edited November 6, 2023 by Thomas Perkins

[Thomas Perkins]

Some one just posted this picture on Facebook and other pictures asking how much it is worth.Check out the temperature gauge.