Heating Issue

I let BLUE run this morning for about 30 minutes before I headed into work to get her warmed up since temps have started dipping down into the 30's. When I got in, the heater was putting out cold air. Not outside temp air, but definitely not warm. So I droven down to the Speedway for my morning cappiciuno , which I might add is awesome! As I was driving the tempature got hot. Sticking to my old military motto, KISS, I am going to change the thermostat first. I alread checked the fluids and such too. No leaks or low fluids. So I am putting a new thermostat in tonight after work. My main question is, sound like a bad thermostat to you?

Check anti freeze level. If its low, you most likely have a leak somewhere.

Check the water pump and the radiator to start. Those plastic ends on the rad like to crack.

Only use HOAT coolant in the kj.

Also, 30minutes is a very long time to let the kj warm up. Probably not the best thing for the engine to let it idle that long. I typically do not idle more than 5minutes.

Edit: Crap, missed the part where you said youve already checked the fluids. Does the gauge show that the engine is getting up to operating temp? If one is handy, an infrared temp gun would tell you the temperature of the engine. I personally keep for for checking things like that, pretty handy to figure out whats going on with an engine. If it shows the engine never reaches operating temp then it can really only be a stuck tstat.

Is your check engine light on? If it is a stuck open t-stat after 2 drive cycles the light will turn on and the code will be P0128.A stuck closed t-stat will make you overheat real fast.

And yes you will loose almost all of the coolant changing the t-stat as the t-stat in the 3.7 is on the bottom radiator hose(engine side).

JeepJeepster said:

Check the water pump

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Yes, this. The symptoms you describe are signs of water pump failure (if nothing else). That happened in a friend's KJ, and both of my husbands Astro vans.

Unfortunately, I just pulled it in the garage and did a more thorough inspection. Looks as if the radiator is leaking somewhere on the top driver side. Same as other posts. Do they still make that stop leak stuff?

Please do not use that stop leak additive crap.
If it can plug the rad what else gets plugged in the process of adding it?
There is a reason why we flush motors and rad to prevent build ups, not create them.
Fix it properly by purchasing a new rad.

I am just getting a new radiator, hoses, thermostat....the works. Just was curious about what peeoples opinions were on STOP LEAK.

Your kJ will Thank You.
You chose wisely!:icon_smile:

yellocoyote said:

Yes, this. The symptoms you describe are signs of water pump failure (if nothing else). That happened in a friend's KJ, and both of my husbands Astro vans.

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You have two husbands? Sucker.

sounds like water pump to me. Or radiator clogged. opening and closing tstat is more to do with engine temps, not heat.

JeepJeepster said:

Also, 30minutes is a very long time to let the kj warm up. Probably not the best thing for the engine to let it idle that long. I typically do not idle more than 5minutes.

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ditto!

It was a cracked radiator. Replaced hoses, thermostat, and radiator.


What should have said is, "I notice that my heat wasn't working this week since the temps dropped. So I let the Jeep run for a longer time than normal to make sure I knew the heat was the problem." I don't wake up every morning to start the Jeep up 30-45 minutes before I do to work. (banghead)


It was not the water pump.

i wish we would get back up into the 30's here... can't remember it ever going below zero before thanksgiving... brrr...

girlfriends 300m has a cold (outside temp) air at idle, warm air while moving issue... it's problem is a $5 fuse that keeps blowing... among a massive amount of other problems, so car is going to get repoed rather than keep fixing and paying for it

JeepJeepster said:

Check anti freeze level. If its low, you most likely have a leak somewhere.

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OP said:

No leaks or low fluids

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Just sayin.

jnaut said:

Just sayin.

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Yeah I was confused about that one too.. Ohh well :shrug:

I am a little lost....

I looked at the coolant level after I got off work and it was low. It was extremely low after my initial post. Its fixed is all that matters.