Jeep Wrangler TJ Cooling System Overhaul FAQ

Chris

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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.
 
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My radiator just overheaded on my 1999 TJ and it is the first time I have had that happen. The light for check gauges came on then when I got home it was overheating. I have 87K miles on it but most were by someone else and I doubt they ever flushed it or maintenanced it. So I am thinking to do the the whole cooling system at once. So it looks like it is about $300 bucks in OEM parts for everything and I am wondering how long it will take ballparkish? Thanks!
 
My radiator just overheaded on my 1999 TJ and it is the first time I have had that happen. The light for check gauges came on then when I got home it was overheating. I have 87K miles on it but most were by someone else and I doubt they ever flushed it or maintenanced it. So I am thinking to do the the whole cooling system at once. So it looks like it is about $300 bucks in OEM parts for everything and I am wondering how long it will take ballparkish? Thanks!

Do it, for sure. Even though it's only 87k miles, your vehicle is 18 years old, which means it's well past due for a cooling system upgrade.

Not to mention that $300 in parts (especially for OE) is not bad at all.

To do all of it, I would say you should plan on 4-5 hours. It can be done in less, for sure, but for the first time, it always takes longer. My time includes breaks, which are a must in my book.
 
Do it, for sure. Even though it's only 87k miles, your vehicle is 18 years old, which means it's well past due for a cooling system upgrade.

Not to mention that $300 in parts (especially for OE) is not bad at all.

To do all of it, I would say you should plan on 4-5 hours. It can be done in less, for sure, but for the first time, it always takes longer. My time includes breaks, which are a must in my book.
Do you think it is worth it to get a mopar fan clutch? They are about 3 x the flex a lite or crown versions.
 
Do you think it is worth it to get a mopar fan clutch? They are about 3 x the flex a lite or crown versions.

Hard to say... I buy Mopar everything because it's tried and tested. But I suspect the Crown one would probably hold up fine. It's all a gamble really. The Mopar one is proven to last 10+ years easily. The Crown one, it's all in the dark to be honest.
 
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Hard to say... I buy Mopar everything because it's tried and tested. But I suspect the Crown one would probably hold up fine. It's all a gamble really. The Mopar one is proven to last 10+ years easily. The Crown one, it's all in the dark to be honest.
Do you order online or is there a particular part store that caries mopar? I found some online places but they charge like $18 for shipping on a water pump.
 
Do you order online or is there a particular part store that caries mopar? I found some online places but they charge like $18 for shipping on a water pump.

Most of my stuff I get from Amazon since it's usually priced the lowest, and it's free shipping.

They have the Mopar fan clutch for $118 with free shipping here:
https://www.amazon.com/dp/B007NN268G/?tag=wranglerorg-20

I never really get stuff at the dealer anymore though. If I can't find the Mopar parts through Amazon, I get them from https://www.wermopar.com which usually has the lowest prices on factory Mopar parts you'll find (Amazon is usually even with them in terms of pricing most of the time).

Unfortunately you'll never find Mopar parts at any local auto part store. Those guys only carry the cheap Chinese brands, which usually end up giving you issues, especially on Jeeps!
 
Most of my stuff I get from Amazon since it's usually priced the lowest, and it's free shipping.

They have the Mopar fan clutch for $118 with free shipping here:
https://www.amazon.com/dp/B007NN268G/?tag=wranglerorg-20

I never really get stuff at the dealer anymore though. If I can't find the Mopar parts through Amazon, I get them from https://www.wermopar.com which usually has the lowest prices on factory Mopar parts you'll find (Amazon is usually even with them in terms of pricing most of the time).

Unfortunately you'll never find Mopar parts at any local auto part store. Those guys only carry the cheap Chinese brands, which usually end up giving you issues, especially on Jeeps!
What's best online place to order? I see several that are focused on Mopar only like Mopar Parts Deals etc.
 
Chris I just swapped my cooling system today and and getting ready to roder MOPAR coolant. It says I need 9 quarts which is 2 1/4 gallons. So I have to buy 3 gallons pre-mixed 50/50 and have 3/4 of a gallon left over? Is my math correct?
 
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What is everyone doing for gaskets on the thermostat? Also, does anyone have recommendations for radiator hoses? I figured while I was doing everything else, I would change out the hoses as well.
 
Chris I just swapped my cooling system today and and getting ready to roder MOPAR coolant. It says I need 9 quarts which is 2 1/4 gallons. So I have to buy 3 gallons pre-mixed 50/50 and have 3/4 of a gallon left over? Is my math correct?

Yep, that is correct!

What is everyone doing for gaskets on the thermostat? Also, does anyone have recommendations for radiator hoses? I figured while I was doing everything else, I would change out the hoses as well.

All of those Stant thermostats I linked to in the first post have the reccomended Stant gasket linked to under "Frequently Purchased Together" on their respective pages. That's what I would use. However, I'll go back and edit my original post to included the gaskets as well. Good call!

Any hose should do, for your 1998, I would use the Gates replacements, they are cheap too!

Upper:
https://www.amazon.com/dp/B000UOE1XS/?tag=wranglerorg-20

Lower:
https://www.amazon.com/dp/B000CHGIA2/?tag=wranglerorg-20
 
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Just replaced my thermostat. Word to the wise, use some kind of gasket maker in conjunction with the seal. After scrupulously cleaning the mating surface and putting everything back together, it sucks to end up having to do it all over again because the things freaking leaks.

Also, I'd recommend buying a Fel Pro thermostat gasket. I compared it to the Stant brand that I bought on Amazon. The Fel Pro is more rubbery. While the Stant is more of a foam.
 
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Thought I'd report here. After 20K miles, my O'Reilly's POS radiator has spring a leak at the bottom tank along the crimp. Do yourself a favor and take Chris's advise and get a Mopar unit. I'm not even going to try and attempt to warranty this piece of crap! Not worth the hassle.
 
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Thought I'd report here. After 20K miles, my O'Reilly's POS radiator has spring a leak at the bottom tank along the crimp. Do yourself a favor and take Chris's advise and get a Mopar unit. I'm not even going to try and attempt to warranty this piece of crap! Not worth the hassle.

That's how they get you. These auto part stores such as O'Reilly and AutoZone (and others) sell you on the "lifetime warranty". Most people buy right into that marketing, and it works.

But ask yourself this... Should that part go bad, is it really something you want to be replacing frequently? If it was just a sensor, I guess I could understand that since it would be easy to replace. However, something like a radiator isn't fun to replace (as you know), so that lifetime warranty is basically worthless IMHO.

In addition to that, they know that most people don't own a vehicle longer than several years, and that lifetime warranty is only good for the original purchaser.

If the OE Mopar radiator can last 10+ years and over 100k miles, that's good enough for me!