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Discussion Starter · #1 ·
Hello All,

I have a potential high operating temp condition with the new (Old) YJ. I have been going through the jeep and have changed out the water pump, coolant houses and put in fresh coolant. It still runs a bit warm on the gauge, between 220 and 230 while driving around. I did hose out the radiator to clean the fins and am planning on doing an old school radiator flush but running lots of water through it as it may be clogged internally.

I did buy a new sensor for the temp gauge but my luck it does not work (rockauto part).

I just don't want to be overly concerned about the jeep running warm if it is just an out of spec sensor. I have not found values for that sensor to test. I am planning on using an IR camera to check the temps as well.

I guess if I wanted a well maintained YJ I would have had to pay more for it.


So short story long. Do we have Ohm values for that sensor?


Bob
 

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When I first got my '87, the gauges worked poorly or not at all.
I pulled the gauge module and cleaned the male and female connector ribbons, along with the printed circuit connections.
This cured the gas gauge, the lights and even got my clock working. But the temp gauge still wasn't right.

I bought a new temp sensor and that made the problem worse. I knew I didn't have a problem with overheating because I checked the thermostat housing and other spots on the engine with a red dot lazer thermometer.
The cure was when I cleaned the probe of the original sending unit on a wire wheel on my bench grinder. The probe (the part that sticks down into the coolant) was black with whatever crud that can collect on it in 20+ years. Once the tip was burnished nice and clean I reinstalled the original sending unit without Teflon tape or any thread sealant. The probe needs to make a good electrical contact, because the gauge relies on a variable ground signal sent by the sending unit. You should clean the threads nice and clean too.

The Factory Service Manual will have the Ohm values.
Let us know how it goes for you.

Good Luck, L.M.
 
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I would strongly suggest filling out your signature with your year, engine, trans, etc. I could probably provide you with an ohms chart if you give me your year.

That sending unit is just a variable resistor that gives resistance on a single wire circuit. High resistance, low temperature. Low resistance, high temperature.

Unplug the connector. The gauge should read zero. Short the connector to ground and the gauge should read max.

This resistance chart is from the 95 FSM and I'm sure it will work with the new style dash which is 92 (I think) - current.

 
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Discussion Starter · #4 ·
Thank you for the specs sheet. I did update my profile. Looking forward to helping others as you are helping me.


Thank you
 

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Discussion Starter · #5 ·
I just measured the sensor. Luckily, at least for this purpose, it is 100 degrees outside in AZ. I think that the sensor may be reading a bit warmer than is should. That is good news.

Thanks

Bob
 

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Discussion Starter · #6 ·
Well I just did some research on the part that I got from Rockauto. I bought a switch not a sender or sensor. That's why is does not work right. Just another proud mistake made by yours truly. I may just buy the right part and be happy.
 

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Discussion Starter · #7 ·
Oh by the way it was reading 1130 ohms at 100F
 

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Discussion Starter · #8 ·
Well I went to autozone and picked up a sensor. Now it reads about 215 which is likely normal for the old girl. I am still going to do the old fashioned flush to it but I am happy that it does not seem that I need an radiator just yet. It has 165K.

Thanks for the help guys.

I did this one with not busted knuckles or use of profanity.
 

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How about the thermostat? If it's sticking closed then you may have an overheat condition.
 
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Discussion Starter · #10 ·
I have just replaced the thermostat, water pump, and all coolant hoses. The only thing left is the radiator if she is running warm.

Bob
 

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Where abouts in AZ?

Do yourself and your jeep a favor. Just pony up the $130 and get a stock style spectra premium radiator from autozone. Mopar cap, and a new fan clutch. Trust me.

You are half way to having an Arizona proof cooling system. Might as well finish the job with the most important pieces.
 

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Where abouts in AZ?

Do yourself and your jeep a favor. Just pony up the $130 and get a stock style spectra premium radiator from autozone. Mopar cap, and a new fan clutch. Trust me.

You are half way to having an Arizona proof cooling system. Might as well finish the job with the most important pieces.
It gets a little hotter in Arizona than in Colorado. DREDnots advice is true, even to those Jeepers living in Alaska.
If you do the job completely, with quality parts and don't cobble things up, your Jeep (or any vehicle) will give you long lasting trouble free service.

Good Luck, L.M.
 

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Discussion Starter · #13 ·
I am sure that is sound advise. I did get a new fan clutch. I will get a new radiator in there soon just to be sure. Its only 36 year old jeep.

I am in Goodyear AZ.

Thanks


Bob
 
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