# Jeep Wrangler problem: Thermostat? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [October 17, 2019, 5:49pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910 "2019-10-17T17:49:53Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 17, 2019, 5:49pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/1 "2019-10-17T17:49:53Z")
I currently drive a 2014 Jeep Wrangler with 70,000 miles on it. Other than tires and oil I have not replaced anything. Last week I happened to glance at the temperature gauge and it was higher than usual. It usually sits midway between cold & hot, it had crept up a bit toward hot. I continued driving and it went back and forth between normal and a bit high. Then, last night I was out and it was a bit chilly. I turned on the heat and got cool/warm air. This morning, I got nice hot air at first, but as the vehicle warmed up I got cool air, then after a few minutes I got hot air. This entire time the temp gauge was up and down. So…IANAMechanic, but I am guessing my thermostat is “bad”. Any reason I shouldn’t buy a new one and with the help of YouTube replace it? I still have the original antifreeze, so I assume I should replace that. Any tips??? ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [October 17, 2019, 5:54pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/2 "2019-10-17T17:54:24Z")
You’re likely due for a flush and fill for the coolant, and I’d replace the t-stat and rad cap at the same time. Cheap insurance. ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [October 17, 2019, 6:00pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/3 "2019-10-17T18:00:06Z")
Have you checked the coolant level? Any visible leaks? I know on my Ranger the water pump has a weep hole, coolant leaking there is an indication of a failing pump. But thermostats are inexpensive and should be easy to replace. In my experience they either fail fully open or closed, but low coolant or a failing pump could cause your issue too. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [October 17, 2019, 6:24pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/4 "2019-10-17T18:24:40Z")
> [@Dag\_Otto](#): > > Have you checked the coolant level? I’d do this first. Some may have slowly evaporated over time and you might have a bubble in the system. My '90 XJ exhibits the exact same symptoms, and it always goes away after a quick top-up (fluid escapes as steam from various places on this vehicle, so its fairly frequent) But I’m a cheap bastard, and will do anything to save a buck. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [October 17, 2019, 8:53pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/5 "2019-10-17T20:53:35Z")
Thirding checking the coolant level before you dig too much deeper. IME, low coolant can make the temp gauge act erratically (since the sensor isn’t immersed in coolant) and will cause cool air in the cab since not enough coolant is making it to the heater core. That’s not to say the t-stat isn’t stuck closed…or stuck open for that matter, but start with the easy stuff. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 18, 2019, 11:44am UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/6 "2019-10-18T11:44:58Z")
I stopped at the local independent auto parts place and bought a bunch of antifreeze (I’m going to drain/flush my Jeep, my gf’s Silverado & Subaru). I priced a thermostat/housing for my Jeep and its $29. After my Jeep cooled down I checked my antifreeze. I was 1/2 a gallon low, so I topped it off. I’ll see if my problem has resolved in a few hours. I also watched some YouTube videos and if I need to put in a new thermostat, I’m set. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [October 18, 2019, 1:15pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/7 "2019-10-18T13:15:09Z")
> [@kayaker](#): > > After my Jeep cooled down I checked my antifreeze. I was 1/2 a gallon low, so I topped it off. I’ll see if my problem has resolved in a few hours. Be sure to let it run with the heater on when you are topping it off, to make sure the heater core is good and full. Work those bubbles out! ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 18, 2019, 1:20pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/8 "2019-10-18T13:20:44Z")
> [@Gatopescado](#): > > Be sure to let it run with the heater on when you are topping it off, to make sure the heater core is good and full. Work those bubbles out! Yeah, there was a ton of bubbles. I drove to work this morning and everything is back to normal. Now I’m all prepared to drain/flush/refill our cars. ---
**Author:** ![Mallard](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@Mallard](https://boards.straightdope.com/u/Mallard)\ **Post date:** [October 18, 2019, 2:37pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/9 "2019-10-18T14:37:06Z")
Congrats on fixing your issue! ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [October 18, 2019, 2:43pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/10 "2019-10-18T14:43:55Z")
Yay! ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [October 18, 2019, 2:49pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/11 "2019-10-18T14:49:57Z")
> [@kayaker](#): > > I stopped at the local independent auto parts place and bought a bunch of antifreeze (I’m going to drain/flush my Jeep, my gf’s Silverado & Subaru). I priced a thermostat/housing for my Jeep and its $29. > > After my Jeep cooled down I checked my antifreeze. I was 1/2 a gallon low, so I topped it off. I’ll see if my problem has resolved in a few hours. > > I also watched some YouTube videos and if I need to put in a new thermostat, I’m set. did you make sure to get the correct antifreeze? if you got the cheap, generic green stuff you’re not going to want to leave it in there for long. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 18, 2019, 3:09pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/12 "2019-10-18T15:09:26Z")
> [@jz78817](#): > > did you make sure to get the correct antifreeze? if you got the cheap, generic green stuff you’re not going to want to leave it in there for long. Yep, checked my owners manual and the guy confirmed my choice. The stuff I added will be wasted, since I’m going to drain/flush/refill now that I know I do not need a new thermostat. ETA: I’m almost bummed out I do not need to replace my thermostat. I watched a few videos, had my tools ready, and was looking forward to it. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [October 18, 2019, 3:22pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/13 "2019-10-18T15:22:39Z")
> [@kayaker](#): > > ETA: I’m almost bummed out I do not need to replace my thermostat. I watched a few videos, had my tools ready, and was looking forward to it. Hey, if you wanna get your hands dirty, I got a list of shit a mile long. I’ll buy the beer. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 18, 2019, 3:27pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/14 "2019-10-18T15:27:01Z")
> [@Gatopescado](#): > > Hey, if you wanna get your hands dirty, I got a list of shit a mile long. I’ll buy the beer. Hey, speaking of “getting your hands dirty”, I noticed all the mechanics posting YouTube videos were wearing gloves. Not cloth gloves, these were latex or nitrile type gloves like a cook might wear. How long has that been a thing? ---
**Author:** ![48Willys](https://avatars.discourse-cdn.com/v4/letter/4/db5fbb/32.png) [@48Willys](https://boards.straightdope.com/u/48Willys)\ **Post date:** [October 18, 2019, 7:04pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/15 "2019-10-18T19:04:52Z")
> [@kayaker](#): > > Hey, speaking of “getting your hands dirty”, I noticed all the mechanics posting YouTube videos were wearing gloves. Not cloth gloves, these were latex or nitrile type gloves like a cook might wear. How long has that been a thing? About 10 years in the shop I work in. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 18, 2019, 7:09pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/16 "2019-10-18T19:09:16Z")
> [@48Willys](#): > > About 10 years in the shop I work in. Seriously? Wow. Other than in the YouTube videos, I’ve _never_ seen a mechanic wearing latex/nitrile gloves. I assume it’s about keeping your hands clean. Greasy/dirty/oily mechanics are a thing of the past? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [October 18, 2019, 8:08pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/17 "2019-10-18T20:08:42Z")
> [@kayaker](#): > > Seriously? Wow. Other than in the YouTube videos, I’ve _never_ seen a mechanic wearing latex/nitrile gloves. > > I assume it’s about keeping your hands clean. Greasy/dirty/oily mechanics are a thing of the past? I’m no more than a shade tree “I think I can fix this” mechanic, but I always wear gloves just because it keeps my hands clean. I think the real mechanics wear them partly to stay a bit cleaner but also to keep the chemicals off their hands. FWIW, [these](https://www.amazon.com/gp/product/B01G346JJ2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) are the ones I really like…they’re textured and make it easier to grab things covered in grease. ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [October 18, 2019, 10:21pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/18 "2019-10-18T22:21:13Z")
> [@kayaker](#): > > Seriously? Wow. Other than in the YouTube videos, I’ve _never_ seen a mechanic wearing latex/nitrile gloves. > > I assume it’s about keeping your hands clean. Greasy/dirty/oily mechanics are a thing of the past? It’s also because used oil/grease is carcinogenic. I usually have nitrile gloves on under my mechanics gloves most of the time. Not a pro mechanic, but I do work on diesel gensets and shadetree my own vehicles. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [October 18, 2019, 10:31pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/19 "2019-10-18T22:31:40Z")
Gloves, schloves. Buy some Lava soap! ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [October 18, 2019, 11:28pm UTC](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910/20 "2019-10-18T23:28:57Z")
Some engines are prone to trapping air in the system creating a hot spot and troubles down the road. If you’re going to flush the system read up on bleeding off any air pockets. Some engines have bleeder valves built into them for just this purpose. [this forum](https://www.wranglerforum.com/f202/how-do-i-bleed-air-out-of-the-cooling-system-2352283.html) discusses it and it appears there’s a bleed valve on the thermostat housing. If this is the same Jeep as yours then you might need an offset wrench to get to it. [Next page](https://boards.straightdope.com/t/jeep-wrangler-problem-thermostat/841910.md?page=2)