Overheating issues still lingering

[Alatex]

Hey guys, still have some slight overheating issues after replacing water pump and thermostat. It’s been driven enough that I would think any trapped air has escaped. If I just drive around town on short trips, it doesn’t overheat, but if I get on the highway it shoots up pretty quickly.

Basically curious what the next course of action should be. Should I park it at an incline and then open the cap and let it run to get the air out if there is any? Is it possible that the thermostat or water pump isn’t running correctly?

 

[TexasTJ2004]

I would say that you need to pressure check your cooling system.
If it holds 14 psi, then your system is properly sealed.
If not, you need to find the leak.
If no leaks, then you still have the fan clutch, and old radiator.
You can replace the fan clutch with new Hayden unit, which is 30$, and you can flush the radiator with thermocure and some BlueDevil/Prestone

 

[RobertJ]

Should I park it at an incline and then open the cap and let it run to get the air out if there is any?

Yes.

Is it possible that the thermostat or water pump isn’t running correctly?

Anything is possible. Did you use a Mopar thermostat?

 

[CharlesHS]

What does your radiator and engine cooling passages look like ?
You should do an inspection to see if there is scale build up in the radiator which would indicate a good chance of the same build up in the engines cooling passages.
IF you didn't flush your cooling system prior to the installation of the water pump and thermostat then as recommended in Post #2 you should flush with Thermocure to increase the heat removal from the engine and cooling capability of radiator.

 

[JMT]

Hey guys, still have some slight overheating issues after replacing water pump and thermostat. It’s been driven enough that I would think any trapped air has escaped. If I just drive around town on short trips, it doesn’t overheat, but if I get on the highway it shoots up pretty quickly.

Basically curious what the next course of action should be. Should I park it at an incline and then open the cap and let it run to get the air out if there is any? Is it possible that the thermostat or water pump isn’t running correctly?

Remove the radiator cap. Start the engine. Let it get up to running temp. When it gets close the thermostat should open. You should know if the hose on the top left of the radiator gets really hot instantly. That indicated thermostat is working. Now look in the radiator cap and see if the coolant is flowing across the fins. If it is your water pump is working. Now squeeze that big hose in the top left to get any air that may be trapped out of there (I.e. burp the system). Return the radiator cap and see how it goes. If you still have overheating on highway flush the system with thermocure.

 

[Alatex]

Yes.



Anything is possible. Did you use a Mopar thermostat?

Yes! It gets to the middle of the 0 in 210 on short town trips or if the speeds stay low and that’s it. But if I get on the freeway and go a bit it will shoot up.

I followed the directions on here for the part number and what not on all things replaced, I did not drill a hole in the thermostat to let air out though. However it’s been a couple months and it’s been driven a good bit around town between now and then so the air shouldn’t be an issue. I’m going to get everything to flush it.

 

[cpwolf]

did you take any pics of rhe opening in the block when you took off the thermostat? Do you know if there was rust build up etc?

I would do the Prestone flush, then I would definitely put the Thermocure in and run it for a day or two so that it gets after it the scaling, runs through the radiator and the block etc.

Drain and pull the thermostat. Leave it aside and fill with distilled , run it for a few minutes no stat so you don’t have to wait for it to get hot to circulate. Repeated with just distilled, until it’s pretty clear.

Then drill the stat, put it back in, and fill with 50/50 HOAT and Distilled.

Then see if it has an issue with the highway. You have to do this no matter what, it hasn’t been done and should be every couple years.

Any chance you have a heater core leak? That will give you system pressure leak.

 

[Alatex]

did you take any pics of rhe opening in the block when you took off the thermostat? Do you know if there was rust build up etc?

I would do the Prestone flush, then I would definitely put the Thermocure in and run it for a day or two so that it gets after it the scaling, runs through the radiator and the block etc.

Drain and pull the thermostat. Leave it aside and fill with distilled , run it for a few minutes no stat so you don’t have to wait for it to get hot to circulate. Repeated with just distilled, until it’s pretty clear.

Then drill the stat, put it back in, and fill with 50/50 HOAT and Distilled.

Then see if it has an issue with the highway. You have to do this no matter what, it hasn’t been done and should be every couple years.

Any chance you have a heater core leak? That will give you system pressure leak.

I don’t think I have a leak. I’m not losing any fluid at all and everything runs well honestly until I get to higher rpms and then it overheats

 

[cpwolf]

I don’t think I have a leak. I’m not losing any fluid at all and everything runs well honestly until I get to higher rpms and then it overheats

Good stuff.

My story isn't perfect, but I tried to follow the directions of some of the very experienced TJ mechanics/experts here.

https://wranglertjforum.com/threads/2005-tj-cooling-system-parts-change-in-texas.63302/

I didn't take out the thermostat to do the quick flush it out, run, flush etc without going to full temp to circulate the whole system, so I took a couple days to get it done, super annoying ha.