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Jeep Wrangler TJ Cooling System Overhaul FAQ

Beastbass27

New Member
Joined
Jul 11, 2022
Messages
2
Location
Texas
Should I replace my entire cooling system at once?
It's a wise thing to do, yes. Let's say you buy a used Jeep Wrangler TJ with 100k plus miles on it. Well, first and foremost you have to know that as I'm writing this in 2017, your vehicle is anywhere between 20 years old (if it was made in 1997) to 11 years old (if it was made in 2006). Either way, if you have no record of the cooling system having been replaced, then you're on your stock cooling system, and even if the miles are lower, that's still a lot of time for a cooling system. Plastic and rubber wear out over time, as do water pumps, thermostats, seals and coolant.

The number one thing that is likely to fail in stop-and-go traffic or long road trips is most likely your cooling system. Replacing the major components in your cooling system is a fairly inexpensive and easy process. Assuming you use OE replacement parts (which is always recommended for longevity), you can expect an easy 10+ years and 100k+ miles out of your new cooling system.

Stay away at all costs from cheap replacement parts from AutoZone, O'Reiley's, NAPA, and other auto part stores. The parts they sell are known to fail prematurely, and will not last nearly as long as OE Mopar replacement parts.

So yes, it's a very wise idea to replace all of your cooling system components at once. In fact, you'd be a fool not to!


What parts will I need?
I've compiled a list of part numbers for the radiator, thermostat and water pump for our Jeep Wrangler TJ vehicles. I figure this information will be very handy when doing a cooling system overhaul.

A few things to take note of here are that in the links above, I'm only linking to OE Mopar parts (as I believe any other cooling system part--especially ones from local auto part stores--are far inferior). The thermostats I'm linking to are Stant SuperStat thermostats with the factory 195 degree configuration. Stant SuperStats are very highly regarded as being better than OE thermostats for our vehicles.

4 Cylinder (SE) Models:

1997-2002 (2.5 liter 4 cylinder)

Waterpump: 4626054AF
Thermostat: 52028186AC
Thermostat Gasket
Radiator: 55037652AA (Manual Transmission)
Radiator: 55037653AB (Automatic Transmission)
Upper Radiator Hose: 52028266
Lower Radiator Hose: 52079670AA
Fan Clutch: 68065080AA
Replacement Radiator Cap: Stant #10234 (yes, this part is a must if you're refreshing your cooling system)

2003-2006 (2.4 liter 4 cylinder)
Waterpump: 4694307AF
Thermostat: 53010552AC
Thermostat Gasket
Radiator: 55037652AA (Manual Transmission)
Radiator: 55037653AB (Automatic Transmission)
Upper Radiator Hose: 52080030AD
Lower Radiator Hose: 52080031AD
Fan Clutch: 68064765AA
Replacement Radiator Cap: Stant #10234 (yes, this part is a must if you're refreshing your cooling system)


6 Cylinder Models:

1997-1999 (4.0 liter 6 cylinder)

Waterpump: 68382489AA
Thermostat: 52028186AC
Thermostat Gasket
Radiator: 55037652AA (Manual Transmission)
Radiator: 55037653AB (Automatic Transmission)
Upper Radiator Hose: 52028264AB
Lower Radiator Hose: 52079670AA
Fan Clutch: 68065080AA
Replacement Radiator Cap: Stant #10234 (yes, this part is a must if you're refreshing your cooling system)

2000-2006 (4.0 liter 6 cylinder)
Waterpump: 5012366AG
Thermostat: 52028186AC
Thermostat Gasket
Radiator: 55037652AA (Manual Transmission)
Radiator (2000-2004 only): 55037653AB (Automatic Transmission)
Radiator (2005-2006 only): 55037653AC (Automatic Transmission)
Upper Radiator Hose: 52028264AB
Lower Radiator Hose: 52079670AA
Fan Clutch: 68064765AA
Replacement Radiator Cap: Stant #10234 (yes, this part is a must if you're refreshing your cooling system)


Should I go with a low temp thermostat?
No, do not buy into the hype that a low temperature thermostat is going to benefit you. There are very, very few cases where a low thermostat will be of any benefit. For 99% of us, they're going to make things worse since the engine will take longer to warm up which can have a handful of negative effects on the engine, performance, and potentially even fuel economy. Whoever started the whole "low temp thermostat" idea needs to be shot, seriously.

Your Jeep was designed by Jeep engineers to operate within a certain temperature range. Making it operate cooler than that designate temperature goes against everything that is programmed into the ECU. There's a reason engineers did the things that they did, and if you're dumb enough to try and reverse engineer it because you think you're smarter than they are, well, then perhaps you're on your way to a Darwin Award :p

Seriously though, all humor aside, don't use a low temp thermostat unless you have some sort of very, very special use case (which doesn't count as "I go rock crawling").


Why do some later model and aftermarket thermostats have either a very small bleeder hole, or no bleeder hole at all?
According to @mrblaine, the later Mopar thermostats and others of similar design have changed the bleeder hole to be nearly non functioning. We've noted the change in the self burping function many times and finally resorted to drilling a 1/8" diameter hole next to the jiggler which solved the problem and made them work as before. The later ones are not self burping in the least until you fix them.

So in other words, you can drill a 1/8" hole in your new thermostat if it has a hole that is much too small, or no hole at all. It's very easy to do and nothing to stress over.

There's a very good discussion on this subject in this thread.


What kind of coolant should I use?
In my opinion you should be using HOAT coolant in your Jeep Wrangler TJ. Hybrid Organic Acid Technology (HOAT) is a combination of IAT and OAT. Several manufacturers are using HOAT for their vehicles. One version is dyed orange and contains 10% recycled antifreeze. Another version is dyed yellow and does not contain any recycled antifreeze. Both of these HOAT antifreezes use the marketing designator of GO-5. They are compatible with each other but mixing them with IAT or OAT is not recommended. The normal HOAT antifreeze service life is 5 years or 150,000 miles (250,000 km).

A perfect example of a good HOAT coolant for use in your Jeep Wrangler TJ is the Zerex G05 coolant.


How much coolant should I use?
See this thread for fluid capacities (it varies depending on which model TJ you have): Jeep Wrangler TJ Fluid Capacities


Tap water or distilled water?
If you are flushing your cooling system or using a coolant that is not pre-diluted, DO NOT use anything other than distilled water. You can buy gallons of it at your local grocery store for less than 99 cents. Distilled water doesn't have the minerals in it that tap water does. If you fill or flush your cooling system with tap water, you will start to see rust build up (which turns brown in the coolant) that occurs sometimes in as soon as months. This will ultimately destroy your cooling system in short order, and make a big mess of things.


How do I replace the radiator?
See this thread: Jeep Wrangler TJ Radiator Replacement


How do I replace the water pump?
See this thread: Jeep Wrangler TJ Water Pump Replacement


How do I flush the cooling system?
See this thread: How to flush the cooling system on your Jeep Wrangler TJ


What kind of hose clamps should I use?
Contrary to popular belief, a "worm gear clamp" is not the way to go with cooling system hoses. What you want to do is re-use the stock "constant tension" clamps (which you can also find on Amazon in various different sizes). The stock "constant tension" clamps are far superior than a "worm gear clamp" because they apply constant tension as the name suggests. The problem with the worm gear clamps is that often times you'll get it tightened down too much, and it can cause a very small leak in one area of the hose where the clamp might not have enough pressure or have something under it causing it to not seal correctly.

I've seen a lot of cooling system hoses (especially radiator hoses) leak, and it was entirely due to the person using a worm gear clamp as oppose to the constant tension style. There's a reason the factory uses the constant tension clamps, and you should re-use them or source out new ones (if yours is missing them) if you're going through the process of overhauling your cooling system.

So I know this thread is old, but I just bought a TJ, and am planning buying all the necessary parts and doing a cooling system overhaul. Should I just drain, flush, replace parts, and refill?
 

TJosh02

TJ Enthusiast
Supporting Member
Joined
Feb 6, 2019
Messages
132
Location
Toronto
So I have had my engine overheat 3 times on me since I bought it 16,000 miles back. All three times I was going down the highway (about 65mph equiv) in warm weather with the A/C on. I pulled off put the heater on full blast and it dropped and didn't rise back. Is this a normal thing, or should I consider replacing the radiator et al?

edit: 02 TJ 4.0L I6, 5sp manual, 120k miles (just turned). 2nd owner, my dad was first who also wheeled
 

TexasTJ2004

I love my TJ
Supporting Member
Joined
Aug 8, 2021
Messages
355
Location
77380
I am overhauling my cooling system right now. My lessons learned:
Your TJ should never overheat. If it does,you have a problem to fix.
How old is radiator and whether it is Mopar or some garbage from AutoZone,like mine.
How old is your thermostat? If you replace, but Mopar one only. Takes two weeks to arrive on Amazon.
How old is your clutch fan? If old, repLce with Mopar or Hayden 2771.
Did you ever flush it? If not, flush with Prestone or BlueDevil.

This week I have replaced the fan clutch, thermostat, and in couple of weeks I will install proper Mopar radiator.
I am flushing with BlueDevil, I am through a second flush cycle, plan 3 BlueDevil in total, and then maybe one more prestone
 
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Dggall

New Member
Joined
Dec 23, 2021
Messages
13
Location
Arizona
Hey Guys,
My radiator just blew up and am researching the best replacement. The threads are emphatic about going with the OEM 55037653AB but it's been discontinued and if there's a place with any residual stock remaining I can't find it. I think I'm at the point of what is the next best option. I'm gathering that the china crap at Autozone, Adavance, etc is the last option. There appear to be many all aluminum "performance" options to choose from. I don't need anything fancy, just need effective and reliable with longevity.

Any help is appreciated.

Thanks,
Dave

2004 Unlimited 4.0 Auto
 

TexasTJ2004

I love my TJ
Supporting Member
Joined
Aug 8, 2021
Messages
355
Location
77380
You still have this at Amazon:https://www.amazon.com/dp/B0049EH4AC/?tag=wranglerorg-20
It is for Manual, not automatic.
I have considered using it, since I already have Derale Transmission Oil cooler, that works independently of radiator, but then I have found a Mopar one for automatic. It was one of the last units on Amazon.

Mopar radiators work for 10 years w/o issues, this is why I am using it.
 

Dggall

New Member
Joined
Dec 23, 2021
Messages
13
Location
Arizona
You still have this at Amazon:https://www.amazon.com/dp/B0049EH4AC/?tag=wranglerorg-20
It is for Manual, not automatic.
I have considered using it, since I already have Derale Transmission Oil cooler, that works independently of radiator, but then I have found a Mopar one for automatic. It was one of the last units on Amazon.

Mopar radiators work for 10 years w/o issues, this is why I am using it.

Thanks for the recommendation. I can appreciate the creativity here but I think the extra expense and complexity is more than what I prefer (at least at this point in my search). Part of it is I'm kind of between homes and have no garage at all. All my repairs are in the middle of an exposed backyard like a hillbilly. I've got lots of tools but most are in storage. So I'm trying to limit the time/magnitude of the job to as close a drop in replacement as possible.
 

Misfito

New Member
Joined
Aug 14, 2022
Messages
2
Location
Hesperia, CA
You still have this at Amazon:https://www.amazon.com/dp/B0049EH4AC/?tag=wranglerorg-20
It is for Manual, not automatic.
I have considered using it, since I already have Derale Transmission Oil cooler, that works independently of radiator, but then I have found a Mopar one for automatic. It was one of the last units on Amazon.

Mopar radiators work for 10 years w/o issues, this is why I am using it.

Hello, I'm new here and checking this thread, since I'm looking into a complete overhaul of my cooling system.
I checked the link that you posted and Amazon says that particular radiator doesn't fit my '97 TJ. Am I missing something?
 

TexasTJ2004

I love my TJ
Supporting Member
Joined
Aug 8, 2021
Messages
355
Location
77380
I think that there are slight differences in the screw holes between the old and new radiators. If you buy this one, you might need to drill couple of wholes