Need Help in Finding Temp Sending unit - Page 2 - JeepForum.com

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post #16 of 28 Old 07-18-2013, 12:51 PM
dnuccio
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1995 ZJ 
 
Join Date: Jul 2012
Location: Phoenix
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Quote:
Originally Posted by sebian View Post
I have the 95 electronics, and the two sensors. One near my t-stat only has the one wire.
huh. maybe it was a monday or friday when it was assembled and the worker put the sensors in backwards

hey at least it works


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post #17 of 28 Old 07-18-2013, 01:03 PM
zjosh93
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1993 ZJ 
 
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Maybe someone jacked with your setup. I've seen ZJ thermostat housings drilled and tapped for the coolant temp sensor for the dash. I think it was to use the later head without the tapped hole already but you never know what some PO may have done.

FWIW my 93 has a two wire sensor in the thermostat housing and a single wire sensor by the back of the head.
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post #18 of 28 Old 07-18-2013, 01:04 PM
AVR2
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2002 WJ 
 
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Quote:
Originally Posted by dellis View Post
I can see where there is indeed a sensor back there on some 4.0's (I can see it is on Cherokees, for example). Here's a drawing:

Yup, that's where mine is. Haynes has a photo of it in that location, which is how I found it, although they also print a diagram taken from the FSM that shows it in the middle of the block underneath the manifold, in line with the freeze plugs, so... go figure.
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post #19 of 28 Old 10-17-2013, 06:32 PM
stretchallen25
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1994 ZJ 
 
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Sorry guys, and not to hijack your thread either but I am having similar problems also. I recently replaced both coolant sensors and the one air intake sensor. Im not sure but my gauge reading starts to get hot. It climbs normally to a temp of about 225 to 230. It before has always ran i little bit below the 210 mark. I did notice that the coolant sensor with 2 wires by the t-stat housing, it will go on both ways and so I was wondering if it matters how it goes onto the sensor. I checked voltage with my DMM and one wire measured 5 volts while the other read 0 volts. So does it matter which way it would go on the sensor? it goes on both ways, meaning I can rotate it 180 degrees and it still goes right on. Thank you very much guys.
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post #20 of 28 Old 10-17-2013, 10:53 PM
Rosslato
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1994 ZJ 
 
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Quote:
Originally Posted by stretchallen25 View Post
Sorry guys, and not to hijack your thread either but I am having similar problems also. I recently replaced both coolant sensors and the one air intake sensor. Im not sure but my gauge reading starts to get hot. It climbs normally to a temp of about 225 to 230. It before has always ran i little bit below the 210 mark. I did notice that the coolant sensor with 2 wires by the t-stat housing, it will go on both ways and so I was wondering if it matters how it goes onto the sensor. I checked voltage with my DMM and one wire measured 5 volts while the other read 0 volts. So does it matter which way it would go on the sensor? it goes on both ways, meaning I can rotate it 180 degrees and it still goes right on. Thank you very much guys.
Just did this last week on my 4.0, here's what i found. Bought one at autozone and it ran 30 degrees to hot and was reading on a forum that the autozone temp sender showed reading's of 30 degrees to hot so i bought one from Advance and it didn't work at all and neither did the replacement so i bought one from Napa ($14) and it reads just before the 210 mark like it should. Also hit the thermostat w/my infrared gun and it read right around 195. hope this helps.

Last edited by Rosslato; 10-17-2013 at 10:56 PM. Reason: to add
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post #21 of 28 Old 10-18-2013, 06:03 AM
stretchallen25
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Oh wow, that sucks. I know these Jeeps dont like sensors unless they are mopar. But I ran it with the cap off to see if the level would go down but it never did. I ran it until the gauge got to about 230 and the coolant level in the radiator never went down, it was slowly going up and falling out of the radiator so Im assuming the t-stat is stuck closed. So I went and got a new one, a 195 degree so I will get that done today and hope thats the problem. Thank you Rosslato. Much appreciated.
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post #22 of 28 Old 10-18-2013, 09:01 AM
PolkaPower
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Air trapped in the system will cause high temps and fluctuation. Think that air is trapped in there?
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post #23 of 28 Old 10-18-2013, 10:15 AM
stretchallen25
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I thought that but I took the radiator cap off and ran it until it was around 235 or so and the coolant level never went down. The top hose is hot but Im not sure if its hot because of the engine department being hot or if just the coolant that was stuck in the intake manifold and upper coolant hose just getting hot. So by the coolant level in the radiator not going down when it gets hot, would it still not go down due to air in the cooling system? Or does that just mean the t-stat is stuck closed? Im not sure and appreciate the help. I dont know how air would get into it because it never had a problem and it has an 18lb radiator cap. I have a new t-stat so should I put it in? Thanks. Oh and I dont have a laser thermometer so its hard to tell.
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post #24 of 28 Old 10-18-2013, 10:25 AM
PolkaPower
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A new T stat won't hurt. Think of it as preventative maintenance. If air was in there it would bubble out and over the top for a little bit then the stat would open and the coolant level would drop. At least it did on mine. It took a few times to get the air out but that's because I drained the coolant and refilled. If you have not done that then you probably don't have air trapped. Also get a new radiator cap. Can't hurt either.
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post #25 of 28 Old 10-18-2013, 11:55 AM
stretchallen25
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Yeah I have not drained it or anything. I checked it with a tester and the coolant checked good. I will get a new cap also and put in the t-stat and let you know if it fixed it. Thank you.
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post #26 of 28 Old 10-18-2013, 11:58 AM
PolkaPower
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Hope it's the T stat!
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post #27 of 28 Old 10-18-2013, 12:00 PM
zjosh93
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An easy way to check the thermostat is to start your engine cold, hold the upper hose, and keep the engine around 2000 rpm. You should be able to feel the rush of hot water when the thermostat opens.
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post #28 of 28 Old 10-18-2013, 01:10 PM
stretchallen25
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Hey guys, I got it fixed. It was the t-stat stuck closed, or it only opened like 1/8 inch so now it is good. I did that and felt for the hot coolant and it came through after I put the new one in. Thanks for the help. It runs at opoerating temp at a tiny bit before 210 on the gauge so I think thats a good temp. I am confused though regarding the fan clutch. When cold, I cant spin it at all, it has a lot of tension and when it warms up, its still the same way and when I am running to operating temp, Once it gets there, I can hear the swoosh that the fan makes, it goes away and gets quiet when it gets hot. Is it supposed to be like that because I was thinking it should be the other way around. Can anyone explain it? Thank you very much guys!
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