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Jeep Wrangler TJ Cooling System Overhaul FAQ

Discussion in 'TJ Frequently Asked Questions' started by Chris, Jan 23, 2017.

  1. Chris

    Chris Administrator Staff Member
    Thread Starter

    Location:
    Salem, Oregon
    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
    Radiator: 55037652AA (Manual Transmission)
    Radiator: 55037653AB (Automatic Transmission)

    2003-2006 (2.4 liter 4 cylinder)
    Waterpump: 4694307AF
    Thermostat: 53010552AC
    Radiator: 55037652AA (Manual Transmission)
    Radiator: 55037653AB (Automatic Transmission)


    6 Cylinder Models:

    1997-1999 (4.0 liter 6 cylinder)

    Waterpump: 4626054AF
    Thermostat: 52028186AC
    Radiator: 55037652AA (Manual Transmission)
    Radiator: 55037653AB (Automatic Transmission)

    2000-2006 (4.0 liter 6 cylinder)
    Waterpump: 5012366AG
    Thermostat: 52028186AC
    Radiator: 55037652AA (Manual Transmission)
    Radiator (2000-2004 only): 55037653AB (Automatic Transmission)
    Radiator (2005-2006 only): 55037653AC (Automatic Transmission)


    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").


    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 OE Mopar coolant. It may be a little pricier, but it's generally going to last longer and be better for your cooling system.


    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
     
    kball05 and Jeremiah Blackwell like this.
  2. PhantomX

    PhantomX Member Supporting Member

    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!
     
  3. Chris

    Chris Administrator Staff Member
    Thread Starter

    Location:
    Salem, Oregon
    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.
     
    PhantomX likes this.

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