mtyson

My '97 XJ i6 4x4 has run hot since I got it. Sometimes the gauge shows hot, sometimes its ok, but always the engine compartment is TOO HOT. Hood HOT to the touch.

I have replaced the radiator and flushed it a couple times. These did not help. Finally, I replaced the thermostat, even though I thought it had been replaced recently. THAT made a pretty big difference.

So it got me thinking, I can be successful at the heat battle. In my research I have found a few suggestions, here they are:

1. Replace mechanical fan with lighter/more efficient electric fan
   • I have read that is isn't a very effective upgrade.
2. Upgrade the thermostat housing to a hesco high-flow version (or similar)
   • This housing has a wider opening and a smoother bend for greater flow
   • This is supposed to improve cooling performance but might not if the flow is TOO great
3. Replace the mechanical fan clutch with the fan clutch from a ZJ
   • I have read people having great success with this, but I do not understand how it could help
4. Move tranny cooling to a separate trans cooling unit
   • To keep the trans heat displacement away from the engine cooling... not sure how this would be done exactly (the one guide I saw on this kept the tranny hot line going through the main radiator)

So that's my research thus far and I greatly appreciate any input, as I'd like to be targeted and efficient in my next upgrade!

mtyson

This is another cooling post, but I wanted to isolate this thing: when running the AC, my '97 XJ i6 gets overheated.

I have verified the electric fan DOES kick on properly.

I notice that the compressor is original looking, ie, old. It does work, but not very efficiently it seems.

Could the old compressor be putting extra strain on the engine via the belt (if the belt wheel is not turning freely when the clutch is engaged)? Could replacing the compressor help?

EEVEE

You must live in a very hot area then. I would suggest a better radiator, I forgot how it went a dual core or row? one of those terms. Anyways typically the stock radiators arent the "best" but they do the job unless you are having heating issues. So i would do a complete flush, replace thermostat, check the water pump and after that is all checked and done put distilled water in there and run a cleaner through it then after thats finished top off with 50/50 here this may help you:
1. The electric fans do help overall if you have the knowledge to do so. Also helps with cooler ac. It depends on the condition of other cooling parts to.

2. I heard of this, I have no clue how they perform so i cant give you any advice.

3. That would work. But there is a few drawbacks to that. First It will roar and roar and roar. Second your gas mileage will SINK from it. And 3 your power will change meaning you have to press the pedal more to go which resulting in the gas mileage loss but in other situations too its kind of dangerous because it wont gain speed (in the case of a friends jeep that has this upgrade) and if you pull out into traffic thinking you can make it think twice lol this video should give an example: Also look at the comments as well here. I dont know if you mind noise but in the mornings this thing sounds like a fighter jet taking off. Also while meandering about i found this video. I didnt watch it but it may be worth a watch:
4. This sounds like it would work. But i dont have anything on personally doing or seeing it.

Thats all the info i have and seen from friends and in person. I would love to do the electric fan conversion but i cant risk my daily being screwed up at the moment. OH and also your fan shroud should NOT be damaged in any way. It WILL drastically make your jeep harder to cool...... i sorta "broke" mine and instead of staying at a steady temp like it used to it not fluctuates from 190 to 210. No biggie but shows how it affects it alot. Mine was loose on the bottom and rattled everytime i started and took off from somewhere and instead of being a smart intellectual and unscrewing it and adjusting it the right way i tried to push the shroud back into the bottom slot. And the end result was a broken fan shroud that is now zip tied to something so it wont rattle, busted knuckle, broken finger nail and punching whatever it was i hit under the engine bay to result in a giant scar on my thumb lol so check over those things.

fb97xj1

How hot has it been getting, exactly? Is it getting hot while driving, or sitting still, or both? The engine bay of an XJ gets pretty toasty, so the hood will get pretty toasty as well. Regardless of what the gauge reads, buy an IR thermometer and point that at the thermostat housing.

Rambler65

Running the AC does increase the heat load on the engine, and the condenser heats up the air being drawn into the radiator. So anything that partly restricts coolant or airflow may cause things to heat up more when the AC is running. I'd look for partly clogged radiator, stuck thermostat, bad water pump, slipping belt, or bad fan clutch for the engine-driven fan. (Both fans need to be working.)

If the AC compressor is not making any bad noises, doesn't leak, and the AC system has correct pressures (should be the case if the AC works) there is no reason to replace it.

mtyson

For completeness, I should add:

1. Installing hood vents.
   • Appears to be very reliable at improving cooling performance. Obviously, it means you have to be comfortable with hacking holes into your hood.
2. Replacing mechanical fan clutch
   • If the mech. fan clutch is bad/going bad, it can cause inefficient cooling. A few ideas are proposed for testing the clutch, but nothing seems conclusive. (My fan seems to be turning very strongly.)

And now for a question -- my mech. fan shroud only goes around the top 1/4 of the fan radius, the rest leaves the fan blades open on the sides and bottom -- is that normal?

nujeepguy

i cut the bottom off my shroud so it would fit. i think,imo, the shroud is mainly to avoid chopping off fingers.
in my 60 yrs of driving 32 different vehicles i have yet to change a fan clutch.
jfwiw

moparado

Make sure the electric fan is working properly.
Both my 2k and old '94 ran hot only when idling for prolonged periods in hot weather.

My fan shroud was also cut on the bottom for apparently easy removal, forgot when or why, had this XJ for 17 years.
Replaced it with a new shroud last time my radiator was replaced neither the new radiator or new shroud made a bit of difference.
Still ran hot when idling.

Fresh flushes, new radiators, thermostats, clutches and a new water pump none of which made a bit of difference.
Still ran hot when idling.

BTY, the replacement fan clutch was a NAPA recommended by some.
Didn't make a bit of difference.

Some of these engines just run hot. Yet some claim they have no temp. issues.

What did make a big difference when idling for prolonged periods was installing a manual electric fan over ride switch.
I can turn on the electric fan at will when i see the temp. creeping up.

Sometime soon, as an experiment i'm gonna wrap the exhaust pipe that comes within 1/8 inch of the engine oil pan.
Hot enough to blister the oil pan paint.
Its amounts to a built-in OEM engine oil heater especially when idling with no air flow cooling it.

salad

Ever replaced the fan clutch? It's a regular wear item. When you have the A/C running your Jeep should sound like a big truck when you hit the throttle. If it doesn't, it's toast.

The fan clutches are viscous couplings that react to heat. The hotter they are, the less slip there is. The ZJ model has less slip overall, and therefore spins the fan faster - which pulls more air through.


Anyway that's all anecdotal - how hot are we talking about here? The coolant temperature is SUPPOSED to run around 100°C. How hot are you calling overheating?

I've merged your threads so we can keep everything in one place as the two issues are entirely related.

moparado

Quick question salad.
Going to a ZJ clutch is another option i'm considering.
Any specific year ZJ or all years?

salad

I believe the same clutch was used on all of the 4.0L ZJs https://www.cherokeeforum.com/f67/zj...clutch-196880/

Rogue4x4

Have you verified temps with an IR gun? When is the issue happening, at idle, or driving?

Don't rely on just the dummy gauge in the cabin. It's just a ballpark.

I live in a place where during the late spring/summer/early fall is triple digit temps most days. A properly maintained cooling system should handle it.

Fan clutches can, and do, go bad. Cheap and easy to replace. Helps with idle temps as it has a viscous clutch that kicks in when it gets hot enough. You can do the ZJ one, but a stocker should be enough in a properly maintained system.

The shroud, yeah you want the whole thing intact. Focuses airflow where it needs to go.

E-fans...multi-core or row rads....some say yeah, some say nah. I have never had problems when I did overhauls with stock components.

Hi-flow stuff....again, some do, some don't. Stock is good enough for me.

Auxiliary cooler for trans lines...great idea, more surface cooling area. This is what they do for tow packages.

Hood vents...does nothing for your actual cooling system, but helps lower underhood temps.

Bottom line here, you need to verify temps underhood...get an IR temp gun, and measure the various points of interest in the system...t-stat housing, upper and lower rad hose...top of rad inlet, bottom of rad outlet...you get the idea. Do it both at idle, and right after a drive. Write it down. If everything checks out ok, start looking at sensors, wiring, relays, etc...maybe you have an intermittent or bad connection in a connector or harness giving a high resistance, and therefore inaccurate reading on the gauge. See where I'm going here?

Troubleshooting these things takes work. But, done the right way, you won't just be guessing and throwing parts at it.

If you don't already have one, get a FSM. Can be had online for around $8 in PDF format. It will have all the steps laid out, right there, for you to do before tossing your wallet at it.

Keep us posted on your progress. These things can be a bear sometimes. I see you live in a spot where good parts might be hard to come by...

Rogue4x4

GOOD MAN, haha

EZEARL

The fan clutch upgrade is NAPA #272310. It's actually not OEM for a ZJ but for 4cyl equipped XJ's.

moparado

When i bought the NAPA clutch, i specifically asked for the 272310 P/N.
The guy behind the counter said that P/N wasn't in stock and could not order it.

I just looked on the NAPA site and there it is: #272310 along with another #272318 P/N clutch listed for my 2k 4.0.
That NAPA guy must of been on drugs or something.
Might try again at another NAPA making sure i get the right P/N this time.

Threw away the NAPA carton so i don't know what the hell i ended up buying, probably the other P/N.
All i know the NAPA clutch i ended up buying had no effect on the temp.

Also, when my Jeep was new i could definitely hear the fan working, sounded like a Mac truck taking off from a standstill.
As the miles piled on that fan sound faded little by little to where i couldn't hear it at all.
One of the reasons i decided to change it.
Can't hear any fan noise either with the NAPA replacement i installed.

Why the two NAPA clutch P/N's?
Only thing i can think of is the 272310 is for police Jeeps and the factory tow package option?
Its also possible the Upcountry package on my Jeep came with the Heavier Duty fan clutch?

Yeah, gonna try NAPA once more.