What’s up everyone. I’m having an issue with my JK running cold temperature readings. when the jeep warms up and the temperature gets halfway after a little bit it drops back down to a quarter reading on my gauge . So I just changed the radiator due to a crack. Then the thermostat. It didn’t solve the issue. I was told it could be the temperature censor so I changed that as well and I’m still having the issue. Could it be possibly that there is some air still in the system even though it was bled?? Thanks for your time

 

These JKs are a bit stubborn to bleed. Lot of times I'll have to top mine off from cold 2 or 3 mornings after. I'd check the level in the rad for the next few mornings and make sure it's right at the top.

 

thanks. I will re bleed after the snow clears. 🤘🏼

 

I would have thought the thermostat would be the most likely thing to keep it from heating up. Does the heater air feel hot? Do you have a way to get the actual temp? Some places may do it for you. I ask because it sounds like when it reaches temperature the thermostat opened up which dropped the water temp down. Are you sure you have the right thermostat (temperature)? I asked about the heater air because it could be the temp is correct and it just not reflecting the temp correctly. On my wife's jeep, 2012, the thermostat stayed in the open position and it actually threw an emissions code. You didn't mention any codes.

 

The heater air gets hot in the middle 2 vents then cools down after a little bit. The end one never get as warm. When I went back to the auto store where the thermostat was purchased, I had asked them if there was another thermostat thinking they might have given me the wrong one. But there was only 1 for my vehicle.

 

Since the heater is not blowing out hot it seems it is running cool. You replaced the block temp sensor already so it should be good. It still acts like the thermostat since it gets to temp and then drops. One other thought is to replace the radiator cap which is easy and could affect the pressure in the system.

 

Ok. I’ll replace the cap today. Thank you soo much for your responses. I’ll keep you posted on the outcome

 

Do you have a scan tool,, I use a Jdiag & JScan.. both can read the actual tempature in F or C. When the engine is cold grab the upper rad hose and squeeze.. if it collapses about 1/2 then grab the lower rad hose & if it is mushy NOT FIRM -- "You Got Mail... ehhh AIR" Burp your system.. Watch this .. excellent on how to:

 

Thanks. Will definitely try. I think it might be a blend door as well. I just need to see which one bc I’m told there are 3. The heat gets cooler in the vents as you move your hand from right to left on the dashboard

 

If you've had the system flushed & filled, there maybe pockets of air within the system. Ideally it best to do these flush & fill while the jeep is on an incline (nose up) as this will help burp the system. Also while doing this, have the heater on as this will siphon coolant to and through the system. Make sure that you're using the correct coolant for your jeep as mixing of HOAT & OAT coolants will cause a chemical reaction, gel then harden over time. In other words replacing one the thermostat is only part of the issue as other issues could be within the radiator or even the engine block.

Lastly, over time after we had our coolant system flushed, we kept getting the strong smell of coolant. Turns out we over filled the reservoir. The radiator heats up the coolant causing this smell. It's best to keep the coolant level below the marks on the reservoir thus reducing the smell. Also, keep checking the plastic "L" shaped coolant lines running to and from your system as these have been known to create hair line cracks.