Air in the coolant system.

[DeLoreanMan82]

How all this started was her original valve cover gaskets were starting to leak oil. Ok, it has 329K original miles. So while in there I went to replace the whole coolant system, minus the heater core. Now this is when it all began. I even removed the water pump to see if the impeller was slipping and that was tight. Removed the thermostat to double check the position of the thermostat and the bleeder and that was fine. Even did a CO2 test and that was fine. Took it to a Jeep dealership and they flushed it and did a CO2 test and THAT was fine still. When I picked it up, I could hear the coolant flowing in the dash which tells me there is still air in the system. So I dug and dug and came upon a post about where people are still having air in the system and everything pointed to the thermostat that it should only be MOPAR. Hey, i'm not doubting them as I been working on cars for 30 years and this has wiped my ass and wouldn't be the first time this Jeep had an issue where I had to use a factory part and that was for the front drive shaft.

Coolant is flowing great, but looking at the bleeder of the MOPAR version looks different than the Dorman version.

When I called the dealer and explained the thermostat issue, they told me that they have issues like that with their Wranglers doing the same thing, using aftermarket thermostats. Customers putting in aftermarket versions, then overheating and then reinstalling a factory piece and TADA, problem fixed!

 

[DeLoreanMan82]

Dorman is never my first choice but with that said, I installed a Murray from O'Reilly. It's all they had and I needed it right away. Temp gauge always sits one tick below the halfway mark. I don't know if the thermostat is your problem. I'm not a very experienced mechanic, but it seems you've tried everything else. My gut tells me your water pump is flaky, and the impeller is slipping on the shaft.

Oh, and btw, her temp gauge ran at the same position as well. When driving there is no issue. It's when you come to a stop and yes, the electric fan works just fine.

 

[Steve1951]

You don't need to go to so much trouble; the cooling system bleeds itself if it is sound. Let me explain: Fill the header/Expansion tank to the cold fill level.
Start the engine, drive until it reaches operating temperature, which is just below the red line on the gauge. Remember the thermostat doesn't open till 90 degrees F.
Park the car overnight, or until it's cold to touch.
The coolant will be recovered from the tank, as long as there are no leaks and the filler cap hasn't been removed.
Top up the coolant. Done!
I always check the next morning, to be sure.

 

[Steve1951]

How all this started was her original valve cover gaskets were starting to leak oil. Ok, it has 329K original miles. So while in there I went to replace the whole coolant system, minus the heater core. Now this is when it all began. I even removed the water pump to see if the impeller was slipping and that was tight. Removed the thermostat to double check the position of the thermostat and the bleeder and that was fine. Even did a CO2 test and that was fine. Took it to a Jeep dealership and they flushed it and did a CO2 test and THAT was fine still. When I picked it up, I could hear the coolant flowing in the dash which tells me there is still air in the system. So I dug and dug and came upon a post about where people are still having air in the system and everything pointed to the thermostat that it should only be MOPAR. Hey, i'm not doubting them as I been working on cars for 30 years and this has wiped my ass and wouldn't be the first time this Jeep had an issue where I had to use a factory part and that was for the front drive shaft.

Coolant is flowing great, but looking at the bleeder of the MOPAR version looks different than the Dorman version.

When I called the dealer and explained the thermostat issue, they told me that they have issues like that with their Wranglers doing the same thing, using aftermarket thermostats. Customers putting in aftermarket versions, then overheating and then reinstalling a factory piece and TADA, problem fixed!

It is wise to test thermostats, even new, genuine, or replacement ones.

 

[burntkat]

... . The bleeder screw is seized shut on my engine, so I parked on.....

I had the same problem with my bleeder screw. I freed it up by driving the vehicle abd then taking a pack of birthday candles (any thin cable or maybe even crayon will do) and let it melt round the circumference of the screw. If it cooled off, drive and repeat. Follow with a shot of PB Blaster. A week of this treatment and the screw broke loose with a minimum of extra effort.
Solve the issue entirely by using pipe dope (aka Teflon thread sealant paste) on the threads upon reassembly. A good high quality (Oatey, et all, not the cheap shit from the parts store) Teflon tape, *properly applied* would work as well.

 

[burntkat]

Sorrry but yeah, the fan does run just fine. That was the first thing I checked and I should have mentioned it in the post.

Be aware that these vehicles have an electric fan in front of the engine driven fan. The drive coupling from the electric fan (ie, wind/air flow) can make it appear that the engine fan is doing its job when it is merely weathervaning from the electric. Be absolutely sure that your fan clutch is good.

Personally, after a run of 3 bad fan clutches (Four Seasons, a reputable brand) causing me to overheat so bad I had to do the heads, I deleted the fan clutch entirely and my fan is now a flex fan driven by the engine. Ie, if the engine is moving at 500rpm, so is my fan. 5500? Same speed as the motor at all times.
Yes it is loud. This is a jeep, not a Cadillac.

I live in the hot, humid SE US. I can idle in 100 degree, 100 % humidity days, or drive way too fast with my lift and cargo, and the temp stays dead set at a tick below halfway. I can get the actual temperature next time I drive using my phone if you need it.

 

[burntkat]

I always use an incline sometimes as much 10° to bleed the air of any of my vehicles coolant system.
Just seems to work better for me.

You want the fill point to be the high point. Such generic device won't always work. You have to assess your situation. Just like with bleeding hydraulics, you need the bleeding point to be the highest point at the cylinder.
Specific to the 05 and similar with the 3.7, flat ground with maybe a little lift to the front left corner so you can pop that bleed screw open (a little!) and retighten it when you see steady stream of fluid escaping, will do you.
A mechanic'a funnel with the inserts that allow you to seal the reservoir and open it with a plunger is a big bonus in this job, too.

 

[burntkat]

My 04 coolant tank had a disaster and had to replace it. I have had air in the coolant system and have periodically topped the overflow tank to the cold fill line. It has taken a number of months but it seems I can barely hear it now. It does seem to slowly work its way out. I do not have functioning AC at this point, but the sound was driving me nuts and glad it is pretty much gone. The whole thing started in September I believe and so it has been about 6 months for it to work its way out. I check the overflow tank every week or so.

Get ready to do heads.....

 

[burntkat]

Oh, and btw, her temp gauge ran at the same position as well. When driving there is no issue. It's when you come to a stop and yes, the electric fan works just fine.

What you are explaining is a classic example of a bad fan clutch.

 

[burntkat]

You don't need to go to so much trouble; the cooling system bleeds itself if it is sound. Let me explain: Fill the header/Expansion tank to the cold fill level.
Start the engine, drive until it reaches operating temperature, which is just below the red line on the gauge. Remember the thermostat doesn't open till 90 degrees F.
Park the car overnight, or until it's cold to touch.
The coolant will be recovered from the tank, as long as there are no leaks and the filler cap hasn't been removed.
Top up the coolant. Done!
I always check the next morning, to be sure.

This is the best way to do it. No special tools needed.