Quality Coolant Temp Sensor Replacment?

[KingCarGuyZ]

Alright, I'm frustrated at replacment parts again.

The Jeep has gone through probably 5 coolant temp sensors in the last 3 years (the one up by the thermostat on the water neck). All of them suffered a mechanical failure of the plastic, where the plug transfers to the brass fitting causing a wildly inaccurate or non-existent coolant temp reading and often a P0118 code. Two of the sensors have been factory MOPAR units, the other's were parts house or amazon replacements. It's not the end of the world I suppose, it's an easy part to change and it doesn't make the jeep un-driveable but I find the failure unacceptable to say the least. Is anyone else having this problem? is there a known quality replacement? I mean if I'm going to have to change it within the year anyway, mind as we'll get the cheapest replacement possible. I know its hot under the hood, especially in Texas summers and right there behind the fan is probably one of the worst spots, but this is getting out of hand - I'm considering hood vents.

 

[Jerry Bransford]

That's an unreasonable amount of failures, are you certain it's not being overtightened when being installed? I've not had a single failure of that part in two TJs.

 

[macleanflood]

Or an intermittent wiring issue?

What's the test procedure for one of these...certain ohm resistance at a particular temperature?

-Mac

 

[KingCarGuyZ]

That's an unreasonable amount of failures, are you certain it's not being overtightened when being installed? I've not had a single failure of that part in two TJs.

suppose it could be the monkey behind the wrench. I wouldn't think I'm over tightening them, It's brass into aluminum so I tend to snug it up, make sure it doesn't leak and call it good.

 

[KingCarGuyZ]

Or an intermittent wiring issue?

What's the test procedure for one of these...certain ohm resistance at a particular temperature?

-Mac

for the sensor I believe its Ohm resistance at temp, every time I test it I have an open loop on the sensor and when I pull the sensor out for more bench testing, it is obviously physically broken.

 

[macleanflood]

for the sensor I believe its Ohm resistance at temp, every time I test it I have an open loop on the sensor and when I pull the sensor out for more bench testing, it is obviously physically broken.

Got any pics of the breakage?

Like Jerry said are you sure you're not overtightening the sensor? Although I am not sure overtightening would break the sensor end...

I sure haven't broken one like this...

-Mac

 

[KingCarGuyZ]

Well the amazon replacement came in today...... and despite the fact that amazon says it fits, the electrical connection is incorrect. So I bought another one from amazon that has the correct connector. Until then, I re-installed the old one and heres what we're working with.

it's hard to see in the photo, but the only thing holing the connector into the brass is the metal blade terminals. one 1/2 decent tug and the electrical connection is coming right out.

 

[KingCarGuyZ]

got the new sensor in from amazon, installed and the problem is solved..... for now.

when I pulled the old sensor out, this is what it looked like:

you can see the obvious problem at the base of the electrical plugin, but there is also a suspicious residue on the end of the sensor, seems harmless but has my attention none the less.

Curiosity got the better of me and I decided to get some destructive testing in, pulled the connector the rest of the way apart and this is what I found.

There was a white paste like substance packed on what I assume is the temperature sensor and around the wires. it appears to be packed inside the main body of the sensor behind the plastic cap or plug that goes into the brass. The red wires are then soldered to the spades that connect directly to the wiring connector. I am not 100% sure what failed before and after diss-assembly but the soldered wires seem like a potential point of failure, and the white paste like substance is interesting to be, purely because I don't know its purpose.

That's all I have, if I'm being honest I probably wont touch the problem until the next one goes bad, but I would love to entertain ideas on keeping these parts from dying. It seems concerning to have such a regular replacement.

 

[Feralkid]

something is probably loose under the hood and pulling on the wire that connects to the sensor plug. the problem has got to be with your jeep not the many sensors you tried.

 

[KingCarGuyZ]

something is probably loose under the hood and pulling on the wire that connects to the sensor plug. the problem has got to be with your jeep not the many sensors you tried.

Interesting theory, I like it. I’ll double check wire routing tomorrow