Temperature switch on 93 cherokee

93redzj

93redzj

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Aug 29, 2005
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Albemarle
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The temp gauge in the dash jumps all over the place, I read that my Jeep should have two sensors, one in the tstat housing being for the ECU And the one in the rear of the cylinder head for the actual gauge itself. When hunting down the rear sensor this is what I found (pic attached) there seems to be a plug for a sensor but no threads in the head for the sensor itself. According to previous owner, the motor was replaced but I’m not sure what year model it came from or if it matters. I’d really like to know what the temp of this thing is when I’m cruising along, how do I do so?
 
Looks like it got broken off in the head. Dig it out with some channel locks and pop a new one in there.
 
It looks more like a flat surface that’s never been drilled and tapped to us, like there was never a spot for one to be threaded in there to begin with. But that’s where it’s supposed to be right?
 
In 96 they changed it for the gauge to run off the T stat housing as well. I had the same issue in my 94 XJ because there is no where to plug that sensor up since the motor is from a 98. I went with an aftermarket gauge, but you could put a factory sending unit in this and use the factory gauge. Just guy by a factory 1 wire sending unit, and order this radiator hose thing to place it in. It has to be grounded though, that’s why I have that janky speaker wire on there after I found out the sending unit has to be grounded. But we don’t need to talk about my janky wiring. It was supposed to be a quick fix before a ride and I just never changed it.
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77GreenMachine said:
In 96 they changed it for the gauge to run off the T stat housing as well. I had the same issue in my 94 XJ because there is no where to plug that sensor up since the motor is from a 98. I went with an aftermarket gauge, but you could put a factory sending unit in this and use the factory gauge. Just guy by a factory 1 wire sending unit, and order this radiator hose thing to place it in. It has to be grounded though, that’s why I have that janky speaker wire on there after I found out the sending unit has to be grounded. But we don’t need to talk about my janky wiring. It was supposed to be a quick fix before a ride and I just never changed it.
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I like this idea, I’ll see about doing something along these lines, thanks!
 
Yep I think I got it figured out what I’m gonna do, I’m gonna do a T fitting in the tstat housing though and run both sensors/switches off the T fitting
 
Keep an eye on that very frequently. That lower fitting is likely going to crack at some point with that amount of unsupported weight vibrating at engine natural frequency.

Did you deadhead another sensor in the end of that stack of 17 brass adapters? I'm not sure what's going on there.
 
Fabrik8 said:
Keep an eye on that very frequently. That lower fitting is likely going to crack at some point with that amount of unsupported weight vibrating at engine natural frequency.

Did you deadhead another sensor in the end of that stack of 17 brass adapters? I'm not sure what's going on there.
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yeah that's an aftermarket temp sender with the coil wrapped tube... Drill and tap the thermostat housing like @Jody Treadway said, I've done it before. Heck I've probably got one tapped already laying around.
 
Fabrik8 said:
Keep an eye on that very frequently. That lower fitting is likely going to crack at some point with that amount of unsupported weight vibrating at engine natural frequency.

Did you deadhead another sensor in the end of that stack of 17 brass adapters? I'm not sure what's going on there.
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Good call didn’t think of that....where would you even drill and tap the housing? If I have issues with this set up then I’ll venture to a junk yard and still one to do the tap trick
 
So, about that brass stack: there's no direct coolant flow to either sensor, so they're only going to work based on the temperature of the brass adapters and the stagnant coolant inside. If they work, you're lucky. They'll have a large lag behind the temperature of the coolant in the rest of the engine, and may not ever reach the same temperature.

Also, you'll have to bleed the air out by loosening that sensor at the end.

I'm trying to say that is not a good solution. :p
 
Fabrik8 said:
So, about that brass stack: there's no direct coolant flow to either sensor, so they're only going to work based on the temperature of the brass adapters and the stagnant coolant inside. If they work, you're lucky. They'll have a large lag behind the temperature of the coolant in the rest of the engine, and may not ever reach the same temperature.

Also, you'll have to bleed the air out by loosening that sensor at the end.

I'm trying to say that is not a good solution. :p
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Noted....and yeah the Jeep didn’t seem to reach but just under 160 on the short trip home from my dads, that seemed odd to me. Looks like my idea wasn’t so great after all. I’ll attempt the drill and tap method
 
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