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???
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.
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.
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.
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.
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.
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?
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 are the ones I really like…they’re textured and make it easier to grab things covered in grease.
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.
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 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.