Hey fella's

Im looking at the mishimoto complete set, fans, oversized radiator, hoses etc https://www.mishimoto.com/jeep-chero...1991-2001.html

my XJ gets pretty toasty, I can see it on the temp gauge and feel it inside the cab even with windows down, I've installed hood vents myself and debating on adding a fan under the hood vents to help assist hot air out, however I was reading up on that some folks have had problems with the OEM rad being undersized, cracking and popping off, so I was wondering if people had any suggestions or have done any upgrades using this MIshimoto kit I'm looking at possibly getting, was also wondering about a water pump that ramps up on low speeds and ramps down on high speeds when I need to rotate more coolant to cool the motor

Thanks!

 

With so many people running the stock system out in the desert areas and no issues. Why would you need all that? Not to be a dick just the system works fine if it's all working correctly. Have you tried giving the block a good cleaning?They contain a lot of nasty stuff inside them after a while.

 

I think the 4.0 is made to run "toasty". Ric is right though, if you do a good coolant flush - oem style components should work fine with a 195 degree thermostat, especially if you have added hood vents. The only "upgrades" I did for my cooling system were air flow related. I made sure the shrouds were sealed all the way around so the fans only pull air THROUGH the radiator and not from the gaps in the shroud. I put a ZJ fan clutch on for more fan speed. A new oem style electric fan with manual control switch, so I can increase airflow as I see fit based on the temp gauge and my operating conditions. Make sure your A/C condenser is not plugged up too, they can get clogged with bugs and road grim over the years and seriously reduce air flow to the radiator. Make sure to get all the air out of the system if/when you do the flush.

 

I mean there is nothing wrong with all those upgraded things if your budget allows for them - they would certainly give you piece of mind knowing you have "the good stuff". But even with them, I would focus on air flow improvements.

 

XJs make a lot of heat. My cooling system works perfectly, and on summer days, my interior gets toasty due to the engine heat. Its just how it is with this vehicle. Think of it as free heating in cold weather.

But if your motor is running hot, that is another story. The Mishimoto radiator for the XJ is known to clog. If you are intent on replacing the radiator, go with a single row Spectra Premium. The full efan system is a mixed bag. It can provide more air flow at idle, but tends to fall behind the factory setup at higher engine rpm.

 

The interiors get hot because of a 200+ degree heater core in the passenger compartment, there's a valve you can install on the heater core lines that cuts off coolant to the heater core

 

No doubt that the heater core contributes, but the firewall and the underbody all become very warm on the inside of the vehicle during driving in 70+ F weather.

 

Years ago I added a Mishimoto radiator and vented the hood - two good things to do for XJ

 

Look for holes in floor or firewall that allow heat into cabin. Seals around shift linkage that leaked made huge leak of very hot air into my rig. Even a small leak need be sealed

 

Everyone has their own take on improving the XJ cooling system, but here’s what I’ve done. I’ve now gone two summers without any major overheating issues:

1. Thermostat – Swapped in a 185° thermostat.
2. Full Cooling System Refresh – Replaced the water pump, thermostat, radiator, and hoses.
3. Time-Delay Relay on the E-Fan – This one’s a game changer. D&E in the Garage has a great YouTube video on adding a time-delay relay to your electric fan. Once set up, the fan can keep running for about three minutes after shutdown. I wired mine to the fog lamp switch, so in summer heat I basically run the fan constantly. When I shut off the Jeep and kill the lights, the fan keeps going for three minutes.

Since doing these three things, I haven’t had a single heat issue. No hood vents either, but I think they look cool.

Your mileage won’t vary—this works.

 

I have been guess and testing with my 90 Renix for years now. Driving on the streets the jeep stays nice and cool. On the trails it starts to get hot when pushed hard up and down the hills in the mountains. Still optimizing the cooling system, though it is sufficient now. Fix/upgrade something and then run it for a while to see how it does.

I swapped in a later OEM radiator with overflow tank, that helped quite a bit. New fan clutch, world of difference. Shrouds all in place. Installed the Rod Louver hood vents, can feel heat pouring out of them on the trail but negligible difference in the time it takes to overheat.

Trans is plumbed into external cooler with radiator cooler bypassed, jeep runs cooler overall but trans is too cold in the winter. I installed a trans temp gauge and it will barely get to 150 in the winter on the streets. Trans runs at 180 on the trails reliably in 4 low. Trans temp climbs if I run in 4 high. Planning to install a larger trans cooler closer to the radiator to improve cooling and a thermostatic valve inline to the cooler to solve the 'too cold' condition in the winter.

I installed a ball valve inline to the heater core to control the heat soaking of the interior - that made a HUGE difference in the summer, cannot recommend enough. I'm sure it's not great for the longevity of the heater core, stagnant coolant in the heater core can lead to corrosion that plugs it up - this is a risk I am willing to take not to cook all summer. Interior will still get hot when the jeep gets over 210 crawling the trails, but stays decent while the engine temp is down around 180.

My experiences are based on trail use in the southeast in the fall/spring. I don't have AC in the jeep and do not like sweating my *** off so I run the jeep on the trails when outside temps are below 80 degrees. I do run the jeep on the streets all year round, though it is just for leisure driving these days - milage is too horrendous to drive to work (average 90-120 miles daily to/from work).

I am about due to flush the coolant - starting to look a little orange again. Will also op-test the mechanical fan as it is 5 years old now - YouTube has some good videos on how to test them. Water pump is probably 15 years old now, plan to yank a heater hose and see the flow rate on the pump when cold. Plan to replace the water pump with a Gates OEM replacement if needed, have not read amazing things about any of the 'upgraded' pumps. I would love to upgrade the radiator to something much larger, but have not read good things about any of the available options.

 

What is the problem you're trying to correct? Engine coolant overheating, cabin temperature, or under-hood engine bay temperatures?

Three different problems with three different solutions.

Don't buy any parts until you've done a coolant flush. The OEM cooling system is perfectly adequate.

 

radiator fan switch- run your electric fan whenever spice into the blue wire on the electric fan side. run to a 4 pole relay, add power and a switch under the dash.