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
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
OE Mopar coolant or
Zero G-05 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.
