Low speed fan sensor on 5.9 is dead.. How do i fix this ? - Page 2 - JeepForum.com
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Unread 03-23-2013, 08:49 AM   #16
PolkaPower
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I have a 180 T stat in there and have my trans cooler bypassed to the aux cooler. It runs way to cold in the winter time as I have recently found out. If you live in the desert that may be fine but My motor takes forever to get warm(180*) and most of the time it's below that especially on the freeway. I found out recently that it has effected my heat inside the cab because it runs so cool. I am going to put a stock T stack back in when It warms up a bit. To cold to mess with it right now.

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Unread 03-23-2013, 08:50 AM   #17
5point9Limited
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http://www.jeepsunlimited.com/forums...d.php?t=538585
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Unread 03-23-2013, 09:10 AM   #18
newfieZJ
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Originally Posted by 5point9Limited View Post

Nice !! I'm gonna do this on mine just because
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Unread 03-23-2013, 09:17 AM   #19
MaintMech
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If the sensor is no good there's a couple of options.

Drill it out.
Start with a small (1/8") bit in the [B]EXACT[B] center of the bad sensor. Then step up in size with the drill until you are about 1/8" under size of the original hole dia. Then use an EZ-Out to extract. If the Jeep Gods are smiling it'll come right out. If not you can use a punch and hammer the sensor away from the threads and get it out that way.

I'm going to assume that the sensor is a standard pipe thread. You can get pipe Tee's that are the correct hose size with the senor size thread. Check any plumbing catalog, Grainger, McMaster-Carr, or even Ace Hardware.

If you want something bullet proof and flashy you can use a copper tee and do the same thing. You might have to sweat in the fitting for the sensor but that's not tough at all.

I don't believe that 10-20 deg. difference on the kick on temp for the sensor will make that much difference to the motor. I suspect that the factory sensors weren't all that accurate.
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Unread 03-23-2013, 09:49 AM   #20
Candymancan
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problem is i dont want my fan to be on 24/7 like people reported.. i dont wanna replace the motor a second time because it burned itself out. clutch fan is on 24/7 true, but its mechanical not electrical like the 5.9 fan so thats different.. Plus the electric fan when its on cools better then the clutch fan does or so i think..

Jeniiferny. I have an aux cooler for my trany on my 5.9 and its bypassed from the main radiator so no in my case my transmission doesnt get as hot or cold as the main radiator.. It stays cooler.. I used a infared thermal probe on my belhousing after a long time.. my tranny was 140-150f vs the oil pan which was 208f. As for mtemps im confused as to what your talking about my 5.9 is always below the 210f notch.. Its usually between the 210f and notch on the left of it.. which is 200f.. Which is also when the low speed fan is suppose to kick off at around 200f or so. Anyone who has a 5.9 has reported this

Factory sensors seem pretty accurate to me, according to the FSM the lower is suppose to kick on at 213f and the upper kicks on at 220 i believe.. Mine according to the digital readng on my OBD reader they kick on at exactly those temps or very close.

Anyway im still wondering what you all think i should do... I'd like to debate pinging and temps ect with you all but in the meentime my Jeep is still reach 225f all the time now and I gatta get it fixed... Im going to the junkyard an hour south of me where i found that white 5.9 3 weeks ago.. In hopes that they still have it or one of the 6 other 98's they have listed on website is a 5.9.. If not waste of quarter of a tank of gas lol
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Unread 03-23-2013, 10:07 AM   #21
5point9Limited
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Quote:
Originally Posted by newfieZJ View Post
Nice !! I'm gonna do this on mine just because
Do it! It is definitely worth doing! Easy, too!
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Unread 03-23-2013, 10:44 AM   #22
coralman
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Isn't the motor a carbon brush type? Would explain the black dusty gunk.
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Unread 03-23-2013, 01:08 PM   #23
5point9Limited
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Isn't the motor a carbon brush type? Would explain the black dusty gunk.
yup
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Unread 03-23-2013, 05:35 PM   #24
Candymancan
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Ok well I went back to the Salvage yard I was at 3 weeks ago where i found a smashed up 5.9.. Thank god it was still there... traffic was freakin horrible today tho... What usually takes 40min to get there took me 2 1/2 hours... i wasm oving like 2 mph for 15 miles... Had to turn my A/C HEAT on full blast to get the low speed fan to kick on and also the heat in the cabin to help cool the Jeep... that helped keep it at 210 or below while i was sitting in traffic..

Anyway the wrecked 5.9 which is the same one i got the amplifier out of 3 weeks ago, had both sensors on the upper and lower hose.. So i just pulled the T fitting out with the sensor.. The bagdes on the 5.9 were gone so i guess another 5.9 owner took em after last i was there..

Hooked up the upper T fitting with the new sensor from the dead 5.9 and the electric fan turns on... However it seems to act differently then my old one did... It comes on at around 203-205f (im watching the temps with my OB2 reader) and then it cools it down to about 194f... but it stays running constantly.. If the temps manages to drop to about 191-192f it will shut off and then turn back on at about 200f again and stay on forever if and when the temps get to 191f which hardly ever happens.. My old one turned on at about 210f and cooled it down to 200 and then turned off. It would only stay on for like 20-30 seconds.. And im talking over the last 2-3 years so prior to it dying on me.. This one litterally stays running for like 10-15 minutes while i was sitting the parking lot watching how it was working..

Is this new sensor faulty as well or is this normal for the fan to come on and stay on for like ever... It does turn off when im driving without stopped and coasting at like 45mph for a few miles before the next stop light... Seems like its staying on a little excessivly.. Im debating on trying the high speed sensor i grabbed as well.. I managed to get it and my old sensor on the T fittings out by using a vice my firestation had.. So it would only take like 10 minutes to swap them and see how that one reacts

It deff keeps the Jeep cooler then my old sensor did.. Both kept the Jeep below the 210f mark on the dash... However my old sensor kept the needle between the middle dash and the dash to the left of it.. This new sensor almost drops the Needle to the dash on the left spot on... Its about 8f cooler then before and like i said runs almost 24/7.. Shouldnt it cycle on then off... Do your electric fans stay on pretty much forever if your sitting idle parked ? Just doesnt seem right to me


See how cold the engine gets because the fan is staying on forever and almost never turns off unless it reachs 191f or so



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Unread 03-23-2013, 10:56 PM   #25
5point9Limited
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My fan kicks on Lo often. It cycles though, off and on. I have a 180* or 190* tstat and mine is exactly where yours is when I am driving on the highway. In traffic closer to 200-205*.
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Unread 03-24-2013, 03:53 AM   #26
Candymancan
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Yea that pic isnt driving its sitting idle the fan is on like 24/7 doesnt turn off until like 190 f.. Im gonna try the other sensor and see if its any diff.. I dont think its suppose to be on that long and cool the engine that much..
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Unread 03-24-2013, 06:50 AM   #27
newfieZJ
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That's exactly where my gauge sits and doesn't move . I'd consider it to be normal and working as it should .
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Unread 03-24-2013, 07:03 AM   #28
Candymancan
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But is your fan on for like 10-15 minutes at a time ? I dunno just seems weird my old sensor like i said for 2-3 years the gauge was around that spot as well.. well was at 200f instead of 192f.. and the fan kicked on for like a minute then turned off.... Mine just turns on at 205f and stays on.. Unless im driving a few miles without stopped then itll turn off finally as the wind from driving cools it down enough to turn off. I guess its a good thing in a way that my transmission will be cooler when idling with the fan running this much.... Maybe the engine will like 190f better then 200+.. i dunno... I just dont want my engine to be running rich from this and for my fan to go bad by constantly running.. I was doing some digging and found a post where a guy said he bought 2 5.9's one with 22k and another with 48k and both had the electric fan running pretty much all the time.. I dunno gah... Maybe im overthinking this..

How much are these sensors worth anyway ? If i were to sell the other one i got
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Unread 03-25-2013, 02:52 PM   #29
gs69350
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Quote:
Originally Posted by Candymancan View Post
Yea that pic isnt driving its sitting idle the fan is on like 24/7 doesnt turn off until like 190 f.. Im gonna try the other sensor and see if its any diff.. I dont think its suppose to be on that long and cool the engine that much..

This could be a sign that you have another issue creeping up. If it has to run that long to cool it down it implies inefficiencies with the radiator/waterpump...

My $.02

I'd just run it until the radiator gets more clogged and it starts overheating at idle with the fan on, could take a while, your ocd with the temps is just giving you a picture of things to come that most people miss.
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Unread 03-28-2013, 11:21 AM   #30
Candymancan
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Well i disagree with that the waterpump is brand new only a year ina half old.. Its true The fan never ran this long before with my old sensor in, it would reach 210f on the OB2 scanner or closer to 205 on the gauge and then kick on and cool it down to 205f on the OB2 scanner and then stop.. This new sensor cools it down to 191-190f then it stops.. I dont see how that is a cooling diffiency sounds more like overcooling to me... That or my old sensor had a slightly higher range to activate and deactivate.. Which is why i was considering putting the other sensor (i got both the high and low speed sensor from that deasd 5.9) in and see if it acts the same way... However after doing some research i found other posts from many years ago with newer 5.9's and two of them did the same thing running all the time.

I dunno... I'll try the other sensor right now since im not doing anything and let you know how the second one reacts. It could simply be as i said and what others always say that each sensor seems to cool at different temps they arent all the same.. Could simply be my old sensor turned on and off at higher temps.. Now that i have running it like this for a week or so now i kinda like it... If it stays on more often it will keep my transmission cooler specially when im at a red light or something.. VS the old sensor that only came on and off for 15-20 seconds
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