Temp gauge is reading 40* to 50* higher than actual temp

[Bruzed]

I verified this by dropping the, grounded, temp. sender in 200* water with a digital thermometer. The digital read 200* the gauge was at 250*

Is it my sender or the gauge that is causing this?

I have recently did a gauge cluster swap to gauges from idiot lights. The sender is new the cluster is from Ebay.

[prerunner1982]

Take a resistance reading of the sensor and compare to below chart.

176 degrees farenheit has a spec between 1,170 ohms and 1,340 ohms
194 degrees farenheit has a spec between 860 ohms and 970 ohms
212 degrees farenheit has a spec between 640 ohms and 720 ohms
230 degrees farenheit has a spec between 480 ohms and 540 ohms

Also just to confirm, you installed the sensor for the analog gauges not a sensor for the dummy light gauge, correct?

[Bruzed]

Thanks that helps a lot.

The sensor is supposed to be for gauges, assuming rock auto sent me the correct one.

[Bruzed]

I give up.

I have bought 4 sensors and every one of them read 232 to 234 ohms at 176*
Using a calibrated fluke meter and cheap digital thermometer that reads 211* at boiling point.

Going to put an aftermarket gauge in it.

[prerunner1982]

Here is the table I found for Renix engines... your sensors almost fall in line with this. Did you verify the part #s were correct.


212 farenheit 185 ohms
160 farenheit 450 ohms
100 farenheit 1600 ohms
70 farenheit 3400 ohms
40 farenheit 7500 ohms
20 farenheit 13,500 ohms
0 farenheit 25,000 ohms
-40 farenheit 100,700 ohms

[Bruzed]

Here is 3 of the 4 part number if have tried. and yes the are verified. Although it is not always clear if they are for gauges or lights.

BWD WT430
Duralast TU236
AIRTEX / WELLS 1T1164 Temperature Sender / Sensor

[prerunner1982]

Here is what I noticed...

Those are noted as being switches instead of sensors. My guess is those are for the "idiot light" gauges and/or electric fan where an action happens at a specified resistance reading.

You might try the SU326 or WT3026.

[prerunner1982]

......

[prerunner1982]

Also... are you checking the right sensor? You may have two of them, one for the gauge and one for the electric fan.

[Bruzed]

I rechecked all the sensors using 200* water in a coffee cup and digital thermometer.

The BWD peged the needle
The Airtex read 250*
The Duralast read 220*

I have decided to use the Duralast for now.

My temp gauge stays slightly over 210* in all driving conditions, which means the actual temp is around 190*

[Mudderoy]

Damn POS factory temp combo (sensor and gauge) drove me nuts for years. At one of our members suggestion I got one of these.

http://www.enginewatchdog.com/tm1.html

http://www.enginewatchdog.com/images/TM1.png

[Bruzed]

Damn POS factory temp combo (sensor and gauge) drove me nuts for years. At one of our members suggestion I got one of these.

http://www.enginewatchdog.com/tm1.html

http://www.enginewatchdog.com/images/TM1.png

I remember you talking about one of those in your Podcast and thought about it. But I would like to get a scanner that tells me what Temp. the computer is seeing. If the computer sensor is not sensing the correct temp the fuel mixture may be off. Remember I have a '96 that has a separate temp. sensor from the comp./efan sensor, un like your later model.

Computer controlled engines are pretty new to me and I have a lot to learn. In other words "I may not understand everything I know about it".:confused:

[Mudderoy]

I remember you talking about one of those in your Podcast and thought about it. But I would like to get a scanner that tells me what Temp. the computer is seeing. If the computer sensor is not sensing the correct temp the fuel mixture may be off. Remember I have a '96 that has a separate temp. sensor from the comp./efan sensor, un like your later model.

Computer controlled engines are pretty new to me and I have a lot to learn. In other words "I may not understand everything I know about it".:confused:

Well I was able to monitor the temp via the OBDII port on my 98, but it just told me the wrong temp too. Of course I just have the one temp sensor, so maybe your OBDI would tell you the other sensor readings.

[the wiltz]

Finding this thread may have just saved me from blowing up my 96XJ!!
i have been fighting "overheating" for a week. Finally started to think that maybe the gauge was just wrong.

temp gauge at 210* sensor reads 310ohm
temp gauge at 240* sensor reads 164ohm

I wonder if I was sold a renix sensor? I will take another reading after the engine cools some.

176 degrees farenheit has a spec between 1,170 ohms and 1,340 ohms
194 degrees farenheit has a spec between 860 ohms and 970 ohms
212 degrees farenheit has a spec between 640 ohms and 720 ohms
230 degrees farenheit has a spec between 480 ohms and 540 ohms

These are the digits for a 1996 XJ right?

Also, looking at the pics of the sensors, i got mine at autozone, i have a white top, not the black one (maybe they sold me the switch)!! I sure hope this is the answer.

will report back tomorrow. Thanks for the great info.

[the wiltz]

Picked up a new TU236 "switch" they say this is for the gauge.
old one:
310ohm@210*
164ohm@240*
550ohm@130*
new one:
160ohm@250*
1000ohm@114*
no where near the figures above.

gauge still seems way off. my gauge says 250* but temp at sendor via laser thermometer is 175*

[Bruzed]

I know for fact that, laser thermometer is not going to give you an accurate reading of the water temp though metal.

The best way to check it by putting your sensor is 200*ish water with a known good digital thermometer and compare the the temperature reading of the dash gauge to the digital thermometer.

You will have to remove the sensor from the motor.
Plug in the sensor to the pig tail.
Ground the sensor body with a jumper wire. There is a ground strap near by.
With the key on (not running) place the sensor in hot water with the digital thermometer wait a few min. to let the sensor settle.

compare the digital thermometer to you gauge.

I did not have luck to the resistance check.

[the wiltz]

I know for fact that, laser thermometer is not going to give you an accurate reading of the water temp though metal.



I know its not precise. but wouldnt it be in the neighborhood? not a difference of 75*?
For instance, I run a 180* thermostat, it opens ( i can tell via the temp change in upper radiator hose) the laser thermometer shows 185*ish at the housing. I would think the sensor would be is the same ball park as the water it is reading.

[the wiltz]

here are the specs from Wells on the sensors that autozone say are correct:
http://www.wellsve.com/custom_searches/pdf/sales_drawings/SU326C.PDF

SU326 - Aux Fan switch

http://www.wellsve.com/custom_searches/pdf/sales_drawings/TU236.PDF

TU236 - gauge sensor.

This doesnt match with what was posted before. Where did the resistance chart come from? And we are talking about a 1996 XJ?

[Bruzed]

I know its not precise. but wouldnt it be in the neighborhood? not a difference of 75*?
For instance, I run a 180* thermostat, it opens ( i can tell via the temp change in upper radiator hose) the laser thermometer shows 185*ish at the housing. I would think the sensor would be is the same ball park as the water it is reading.

Yes is should read close enough though the aluminum Tstat housing.
I thought you were trying to get a reading near the temp. sensor in back of the head.

I took me 4 sensor to get one that was only 20* off.

[the wiltz]

Yes is should read close enough though the aluminum Tstat housing.
I thought you were trying to get a reading near the temp. sensor in back of the head.

I took me 4 sensor to get one that was only 20* off.


While doing tests on the stand alone temp gauge ad sendor I did some tests on the temp difference between the new gauge and the laser temp at the sensor. The gauge and the temp via the laser on the wrench flats of the sensor were dead on. maybe a couple degrees different.

I gave up on trying to make the stock unit work I tested 2 sensors and got 3 different results... $25 for an aftermarket stand alone works fine for me.

[Bruzed]

While doing tests on the stand alone temp gauge ad sendor I did some tests on the temp difference between the new gauge and the laser temp at the sensor. The gauge and the temp via the laser on the wrench flats of the sensor were dead on. maybe a couple degrees different.

Good to know that works

I gave up on trying to make the stock unit work I tested 2 sensors and got 3 different results... $25 for an aftermarket stand alone works fine for me.

I may do the same thing. I don't have a lot of confidence in mine.

[4.3LXJ]

For what it is worth guys, my temp gauge is spot on. It is an 86 temp gauge. You guys might try one of the early AMC sensors and see what happens. They take 1/8" pipe thread