I've skipped the thermostat gasket on at least two 4.0s. Your Jeep, your call.
Right stuff sealed them both up.
-Mac
Jeep Wrangler TJ Cooling System Overhaul FAQ
- Thread starter Chris
- Start date
I've skipped the thermostat gasket on at least two 4.0s. Your Jeep, your call.
Right stuff sealed them both up.
-Mac
Alan Covey
New Member
I'm chasing a slow-to-heat condition again as the weather is getting colder here in NC. I want heat this winter! I replaced radiator, water pump, flushed and filled coolant, and probably its the thermostat again...but am trying to get down to whether the other MOPAR parts on this list are still available and what alternatives are best to go with next...
Looking back a few pages I see a members Rock Auto order list, but when I check the water pump against their stock numbers they list the 68382489AA as cross referenced to 4626054AF, but my 1998 Sport 4.0 (Automatic Trans/With AC) is not listed in the model numbers. Are they confused or not up-to-date as MOPAR has discontinued parts for the older TJ's? Will other parts numbers not match up from that list?
I'm very confused, as it seems that Chris' recommendations/list-of-parts at the top has not been refreshed in some time. Probably a good idea to share the latest parts order list and the sources we order from to re-confirm the sticky list...saves going through 15 pages back-through-time to find current info here. Just a few thoughts as I sort this out and hit the "Purchase" button...
Sparky the WonderJeep says Thanks guys!
Looking back a few pages I see a members Rock Auto order list, but when I check the water pump against their stock numbers they list the 68382489AA as cross referenced to 4626054AF, but my 1998 Sport 4.0 (Automatic Trans/With AC) is not listed in the model numbers. Are they confused or not up-to-date as MOPAR has discontinued parts for the older TJ's? Will other parts numbers not match up from that list?
I'm very confused, as it seems that Chris' recommendations/list-of-parts at the top has not been refreshed in some time. Probably a good idea to share the latest parts order list and the sources we order from to re-confirm the sticky list...saves going through 15 pages back-through-time to find current info here. Just a few thoughts as I sort this out and hit the "Purchase" button...
Sparky the WonderJeep says Thanks guys!
What temp is the engine running? Not what temp you think it's running but what temp is it actually running? A non contact thermometer can be helpful. Also, a code reader with the ability to read live data is helpful as well.
Have you ever replaced the heater core? Have you checked to verify it flows well?
Don't keep throwing parts at it. Figure out what the problem is and then fix that.
Lots of great information within this thread. Special thanks to those mentioned below. In my case, I did a full overhaul of the coolant system including thorough flushes, hose replacements, component replacements, and complete cleaning of reservoir tank. Incidentally, I also installed a bypass valve for the heater coil, and replace several drive belt components. Here are a few highlights/contributions to this thread. For details, DM me, I wrote up an action/procedure and part/tool list that I'm happy to share. This for a bone stock 2003 X, 4.0 manual.
Results:
1) Peace of mind.
2) Gauge never reaches the 210 mark, maintains ~195.
3) Ability to bypass heater core/reduced heat load in cabin.
General Items:
1) Isolate the system components for flush (rad, core, block) and flush forward/backward.
2) Flush existing system. DRIVE, don't just idle. Can't say this enough.
3) Crystal Springs and other water vendors will sell 5-Gallon distilled water. Most require pickup for this.
4) Engine coolant plug is moderately difficult to get to, but well worth the effort and you don't have to pull the fender liner.
5) Coolant plug is 8MM square, and the location is designed for direct approach with a 3/8" extension. 3/8" MPT fittings and flexible hose are useful here.
6) Fan clutch is standard right hand thread. Not reverse thread. A fan clutch wrench was critical in my case.
7) The system is self-burping if the t-stat hole is crated as mrblaine has explained. Use the hoses, especially upper rad hose, to force bubbles through.
8) If you are in a suburban or urban setting, gameplan your coolant disposal. Most municipalities have options for this.
9) Thermocure yielded better results than blue devil. Blue devil did well, but the flush after with thermocure was incredible.
10) Clamp pliers are WORTH IT! As are new hose clamps.
11) The hard pipe is worth reciting. Though new ones are very cheap.
12) Take your time and thoroughly clean gasket mating surfaces. This is well worth the time you put into it. Dremel had some good non-aggressive options.
BRASS Bypass Valve:
1) Here's the baseline product: https://www.amazon.com/dp/B0989GCHX6?tag=wranglerorg-20
2) You'll need to purchase the 3/4" and 5/8" sizes. In the end, you'll have two bypass valves. I have a second, DM me if interested.
3) You'll need to partially disassemble/reassemble units to create the correct hose port sizes. This is very easy, and be sure to use sealant.
4) When complete, you'll have a manual bypass valve that will prevent unwanted heat in the cabin.
Special thanks:
Chris Thank you for this thread https://wranglertjforum.com/threads/jeep-wrangler-tj-cooling-system-overhaul-faq.3397/
TJDave Thank you for this thread https://wranglertjforum.com/threads/how-to-flush-the-cooling-system-on-your-jeep-wrangler-tj.1737/
Jeepwx03 Thank you for the post with fittings for separate component flushes!
mrblaine Thank you for all of the information (in this thread and others) about the thermostat and inspiring me to assembly a manual bypass for heater core!
Jerry Bransford thank you for the helpful picture/location to drill hole in thermostat.
Altonymous Thank you for recognizing the coolant drain plug socket size!
Nightmare9 thank you for th pointer about driving. What a difference this makes.
zebra12 thank you for the intro to Thermocure Evaporust. I'm a believer in it.
01TJ-Blues thank you for identifying the coolant plug size. Brass pipe extended from this made flushes and cleanup a breeze.
59 wagon man I know have a clamptite tool. Not used on this project, but a must-have for my triage tool box.
MountaineerTom thank you for the help with the constant tension clamps and permeated pointer! https://wranglertjforum.com/threads...urces-for-constant-tension-hose-clamps.28271/
Link thank you for the pictures of the rad!
Results:
1) Peace of mind.
2) Gauge never reaches the 210 mark, maintains ~195.
3) Ability to bypass heater core/reduced heat load in cabin.
General Items:
1) Isolate the system components for flush (rad, core, block) and flush forward/backward.
2) Flush existing system. DRIVE, don't just idle. Can't say this enough.
3) Crystal Springs and other water vendors will sell 5-Gallon distilled water. Most require pickup for this.
4) Engine coolant plug is moderately difficult to get to, but well worth the effort and you don't have to pull the fender liner.
5) Coolant plug is 8MM square, and the location is designed for direct approach with a 3/8" extension. 3/8" MPT fittings and flexible hose are useful here.
6) Fan clutch is standard right hand thread. Not reverse thread. A fan clutch wrench was critical in my case.
7) The system is self-burping if the t-stat hole is crated as mrblaine has explained. Use the hoses, especially upper rad hose, to force bubbles through.
8) If you are in a suburban or urban setting, gameplan your coolant disposal. Most municipalities have options for this.
9) Thermocure yielded better results than blue devil. Blue devil did well, but the flush after with thermocure was incredible.
10) Clamp pliers are WORTH IT! As are new hose clamps.
11) The hard pipe is worth reciting. Though new ones are very cheap.
12) Take your time and thoroughly clean gasket mating surfaces. This is well worth the time you put into it. Dremel had some good non-aggressive options.
BRASS Bypass Valve:
1) Here's the baseline product: https://www.amazon.com/dp/B0989GCHX6?tag=wranglerorg-20
2) You'll need to purchase the 3/4" and 5/8" sizes. In the end, you'll have two bypass valves. I have a second, DM me if interested.
3) You'll need to partially disassemble/reassemble units to create the correct hose port sizes. This is very easy, and be sure to use sealant.
4) When complete, you'll have a manual bypass valve that will prevent unwanted heat in the cabin.
Special thanks:
Chris Thank you for this thread https://wranglertjforum.com/threads/jeep-wrangler-tj-cooling-system-overhaul-faq.3397/
TJDave Thank you for this thread https://wranglertjforum.com/threads/how-to-flush-the-cooling-system-on-your-jeep-wrangler-tj.1737/
Jeepwx03 Thank you for the post with fittings for separate component flushes!
mrblaine Thank you for all of the information (in this thread and others) about the thermostat and inspiring me to assembly a manual bypass for heater core!
Jerry Bransford thank you for the helpful picture/location to drill hole in thermostat.
Altonymous Thank you for recognizing the coolant drain plug socket size!
Nightmare9 thank you for th pointer about driving. What a difference this makes.
zebra12 thank you for the intro to Thermocure Evaporust. I'm a believer in it.
01TJ-Blues thank you for identifying the coolant plug size. Brass pipe extended from this made flushes and cleanup a breeze.
59 wagon man I know have a clamptite tool. Not used on this project, but a must-have for my triage tool box.
MountaineerTom thank you for the help with the constant tension clamps and permeated pointer! https://wranglertjforum.com/threads...urces-for-constant-tension-hose-clamps.28271/
Link thank you for the pictures of the rad!
That’s a pretty cool bypass valve. I’d not seen that before. Thanks for posting.
That's really nice!! Looks good! I might consider doing something like that in the future! Nice job!
So my question is: what is the downside in placing just a ball valve cutoff in the heater line, ie stopping flow thru the heater loop?
Good question, and would appreciate the forum's input. I'll post here if any concerns arise. In the research process, it seemed (generally) that most concerns could be addressed by periodic operation of the system in a non-bypass, normal circulation path.
FWIW, a local rad shop was very helpful in understanding load transfer to radiator when bypassing the heater loop. An incremental load is transferred to the rad during bypass. In my scenario, the after-market Dorman radiator is designed for cooling capacity with standard or automatic transmission use. Since I have a standard transmission, the incremental additional load was inconsequential. Interestingly, the rad shop was also unconcerned about load transfer to rad with an automatic transmission in normal operating conditions.
We discussed this on another forum for Ford trucks and the general consensus was it's OK to do that as long as you periodically open it and let the coolant circulate. Apparently (some, most or all?) factory systems allow some coolant to flow thru the heater core all the time to keep it from getting stagnant, or from causing clogging issues. Some coolants become acidic after a time and that can be detrimental as well. there are after market heater control valves that you can buy that will stop the flow completely while the AC is running, and there is a Ford Ranger valve from certain years that is popular to retrofit into the bigger trucks.
Also some trucks came with a valve that closes off the flow when on Max AC.
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Interesting! I’ve been running the ball valve on both my TJ 4.0 & my 74 CJ5 304V8 for a while. Thought I’d throw it out for discussion .
I’ve been running the ball valve on the heater loop on both my TJ 4.0 & my 74 CJ5 304V8 for a while. Thought I’d throw it out for discussion.
I’ve got a question and I feel this is a good spot to ask it. I’ve got a question about overheating. I’ve got a 97 TJ with 168k miles I’ve got a new motor, with low gearing. I’m on 35s and I believe its 4.56 gearing or lower. It’s a manual. I’ve got a winch.
When I drive on the freeway at 65-70 uphill or on a medium incline at 70 degrees or Warner outside my temp gauge pushes up to 250 and eventually gets to 260 and I pull over to let it cool. I’m not expecting to get over 55 going uphill because of my gearing etc, but I’d like to upgrade something on my Jeep whether it be good louvers or a high powered electric fan.
Anyone have any recommendations?
I’m good on all my fluids and my fan runs well when it gets hot. I got a new radiator when I got my new motor and no leaks.
When I drive on the freeway at 65-70 uphill or on a medium incline at 70 degrees or Warner outside my temp gauge pushes up to 250 and eventually gets to 260 and I pull over to let it cool. I’m not expecting to get over 55 going uphill because of my gearing etc, but I’d like to upgrade something on my Jeep whether it be good louvers or a high powered electric fan.
Anyone have any recommendations?
I’m good on all my fluids and my fan runs well when it gets hot. I got a new radiator when I got my new motor and no leaks.
What engine are you running, and which radiator did you install? When did this start happenning?
A properly functioning stock cooling system will work fine. Something is not right with yours, and you need to identify the actual problem and correct it. Louvers, a high powered electric fan, or any other quick fix will not help.
It’s got the 4.0 and an OEM replacement radiator. And I’m not sure that it’s the “right” reason but it could be just me getting pin the skinny pedal trying to keep my momentum going up hill because of my low gears. Does that seem like it would be a possible cause or is there still an issue somewhere?
What do you mean by OEM replacement radiator? A Mopar unit or aftermarket?
There is still an issue somewhere. The rig should stay cool even going up hill.
Have you ever given it a proper flush?
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 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.
It's 2024 & this post has saved my life! Doing the Lord's work here, truly.
OP
Thank you! I wish I could find a way to connect this to doing the Lord’s work but I’m not sure I would go that for. Still, I thank you for that comment and God bless!