engine temp senor help now !!!!
so i was in the process of replacing the engine temp senor when the top half broke. so i must get out tonight. i was using a 14 mm which fits the new but looks like the old one use 13mm. the socket is having trouble gripping it. and sugestiong or tips on what tools to use or way of taking it out.
would it hurt the engine if i run with out the engine temp senor?
would it hurt the engine if i run with out the engine temp senor?
Senior Member
Joined: Jun 2009
Posts: 670
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From: Central Pennsylvania
Year: 1989
Model: Cherokee (XJ)
Engine: 4.7 H.O.
Ok I'm assuming that your talking about the coolant sensor on the back driver's corner of the head cuz I did the same thing and sizes sound the same, it's brass and therefore soft, drill it out with a bit just a touch smaller than the sensor, it should leave just a pigs tail of brass around the edges (there's a name for this but I can't remember what it's called something coil), then very carefully, pull this brass out or use a threading tool to push it through (won't hurt the cooling system brass is soft). Just be careful drilling. And no it won't hurt the engine to run without it, you just won't have a temp gauge until it done, just make sure to connect the new temp sensor to the wires and zip tie it out of the way where it won't be damaged til you have time to do this otherwise you will throw a code for temp sensor short circuit.
Last edited by sv41878; Oct 7, 2009 at 11:14 PM.
Senior Member
Joined: Jun 2009
Posts: 670
Likes: 0
From: Central Pennsylvania
Year: 1989
Model: Cherokee (XJ)
Engine: 4.7 H.O.
Your good then, I still haven't fixed mine, it wasn't working when I got the Jeep, I broke it Saturday trying to take it out and haven't had time to drill it out myself, I just did what I just suggested to you, plugged it in and tied it out of the way. The brass they use for that is really crappy, they break all the time.
Senior Member
Joined: Jun 2009
Posts: 670
Likes: 0
From: Central Pennsylvania
Year: 1989
Model: Cherokee (XJ)
Engine: 4.7 H.O.
Not unless you had one before, keep an eye on it, but I haven't and my aux fan doesn't work either, think it has something to do with that sensor being broken.
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Junior Member
Joined: Sep 2009
Posts: 86
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From: Saskatoon, SK
Year: 1988
Model: Cherokee
Engine: 4.0L
before resorting to drilling it out try an imperial size socket 1/2 inch or 9/16 should fit - the 1/2 inch will probably need to be forced on but should grip enough to turn it.
good luck
good luck
Senior Member
Joined: Jun 2009
Posts: 670
Likes: 0
From: Central Pennsylvania
Year: 1989
Model: Cherokee (XJ)
Engine: 4.7 H.O.
I don't understand, you drilled it out and it leaked coolant? Did you not screw the new one in, use to big of drill bit? You shouldn't have any problem with drilling it, make sure the drill is straight, one size smaller than the threads on the fitting and use a threading tool to get the rest of the brass out, then use RTV sealant on the threads.
If you drill that out, bear in mind that the hole is tapered, and you'll use a 1/8" NPT tap to clean up the threads. Do not cut any new threads, or you'll screw up the hole!
Seal the new sensor using RTV copper - this will preserve the "self-grounding" property, and will help prevent seizure next time.
@sv41878 - If your fan isn't working, it's not that sensor. It only drives the IP gage/lamp. What year is your rig? 1987-1990 uses a Thermal Fan Switch (TFS) in the driver's side radiator tank, while 1991-up fan relays are driven by a signal from the ECU, which is derived from the coolant temperature sensor in the thermostat housing up front.
If you don't have any codes, the sensor itself is good - so check the relay (should be on the driver's side fender liner) and fan modules instead.
Senior Member
Joined: Jun 2009
Posts: 670
Likes: 0
From: Central Pennsylvania
Year: 1989
Model: Cherokee (XJ)
Engine: 4.7 H.O.
Mines a 96, I've been through everything, all I can figure is that because that doesn't register a temp, the ECU doesn't pick up that the aux fan should kick in, but I'm not having any issues with it not working either.
so i tried to take it out yesterday and found out that socket wouldn't go all the way down it hits the valve cover case i tried a wrench but they are to big. thats why it was slipping. any other tool i can use?



