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96 Running Hot

cshontz

NAXJA Forum User
Location
Lancaster, PA
My 96 XJ (100k) is running a little hot - always 220+, and the needle climbs into the red at idle or on the trail.

I just replaced the water pump, thermostat (cst 3839 195), and coolant. I think the temperature was a little high before performing this service, but I think it became worse after the service.

The temperature does goes down when I turn the heat on.

The aux fan seems to come on at the right temperature.

I tested the mechanical fan clutch using ESP, and it seems okay, but I can't confirm. Other clutch test recommendations?

My coolant level is good, and I assume it is free of air. Old coolant was discolored brown. New coolant looks relatively good so far.

Otherwise, the Cherokee is running well, but I want to bring it back down to 210. I'm all tapped out, so I don't want to spend much.

What steps do you think I should take to diagnose this high temperature problem?

I'm suspicious of the thermostat - although there is little basis for this suspicion. Any way to test its operation?

Should I have the cooling system pressure-checked? If so, what indicates good pressure? Is it a numerical value? I would have a local shop do this.

I did a search for this problem and came up with several hits that I found informative and useful. I'm posting this to get help or advice that is personal and specific to my case.
 
I would replace the T-stat, a 195 from the dealer or a 180 depending on where you live and what type of driving. now that I just looked and see your in PA. I run a 180 Jet T-stat in mine and it stays cool on the highway and gets up to 190-195 in traffic and trail use. I do that the closed loop system, 3 row rad, Turbo City T-stat housing, stock electric fan, rebuilt Autozone water pump, and stock fan clutch. T-stat or Rad would be a good place to start. Juice
 
This may sound basic but since you said you take your Jeep off road make sure your radiator is clean. I had a Jimmy that I used to take on the trails, I know big laugh, but it started overheating like crazy and I could not find the source. I eventually got the idea to spray both sides of the radiator down real good with the garden hose and I was suprised how much dirt I got out of there. It solved the problem completely and now I make sure I do the same with my XJ after going through any mud.
 
You talked of brown coolant, I'd says your radiator at 8 years old may be at the end of it's service life. You have more than 7 years on the radiator, sounds like it was not well cared for so replacement is high on my suggestion list.

Also there is no good test for a fan clutch, they give false results. I'd also replace the fan clutch.

Once you have the radiator and fan clutch replaced I'd install a new dealer thermostat - use a 195F - and install a new radiator cap. The dealer thermostat has a hole to let the air bleed out, the aftermarket thermostats does not have that hole. My radiator shop in st louis told me if i got my thermostat to 225F one time it will have perminate damage. Hard to believe with engines running 200-210 but the nature of mateirals I have no problem believing after my one time overheat. Finally fixed it with a new thermostat.

When you refill use distilled water along with your coolant. Also before you pull the old radiator you may want to pull your current thermostat and drain the coolant, fill and drain a two or 3 times with distilled to get all the old coolant out. Then when you pull the radiator and install the new radiator. When filling I find it easier to dump in 6 quarts of full strength coolant then top off with distilled. The published volume for my year is 12 quarts, this method worked well for me the times I have changed coolant.

If you change the radiator pick up your hoses at the dealer. They look better than the goodyear ones on put in my XJ in 2000. In Feb this year I installed the dealer hoses, they have the antichafe on the outside and a full length spring on the inside of the bottom hose.

Sounds like it's time for a cooling system renewal, also make sure your electric fan is plugged in. Don't ask me how I know that lesson :)
 
juicexj24 said:
I would replace the T-stat, a 195 from the dealer or a 180 depending on where you live and what type of driving. now that I just looked and see your in PA. I run a 180 Jet T-stat in mine and it stays cool on the highway and gets up to 190-195 in traffic and trail use. I do that the closed loop system, 3 row rad, Turbo City T-stat housing, stock electric fan, rebuilt Autozone water pump, and stock fan clutch. T-stat or Rad would be a good place to start. Juice

Heya, Juice. You know me - this is Chris. I sold you the Eccos. :p

94DCXJ said:
This may sound basic but since you said you take your Jeep off road make sure your radiator is clean. I had a Jimmy that I used to take on the trails, I know big laugh, but it started overheating like crazy and I could not find the source. I eventually got the idea to spray both sides of the radiator down real good with the garden hose and I was suprised how much dirt I got out of there. It solved the problem completely and now I make sure I do the same with my XJ after going through any mud.

My radiator is pretty clean. I only just started using this Cherokee on trails. It has been on 4 runs, and I stay out of mud when when I can. Good suggestion, but I'm pretty sure its fine in this regard.

xj0204.jpg


martin said:
You talked of brown coolant, I'd says your radiator at 8 years old may be at the end of it's service life. You have more than 7 years on the radiator, sounds like it was not well cared for so replacement is high on my suggestion list.

Also there is no good test for a fan clutch, they give false results. I'd also replace the fan clutch.

Once you have the radiator and fan clutch replaced I'd install a new dealer thermostat - use a 195F - and install a new radiator cap. The dealer thermostat has a hole to let the air bleed out, the aftermarket thermostats does not have that hole. My radiator shop in st louis told me if i got my thermostat to 225F one time it will have perminate damage. Hard to believe with engines running 200-210 but the nature of mateirals I have no problem believing after my one time overheat. Finally fixed it with a new thermostat.

When you refill use distilled water along with your coolant. Also before you pull the old radiator you may want to pull your current thermostat and drain the coolant, fill and drain a two or 3 times with distilled to get all the old coolant out. Then when you pull the radiator and install the new radiator. When filling I find it easier to dump in 6 quarts of full strength coolant then top off with distilled. The published volume for my year is 12 quarts, this method worked well for me the times I have changed coolant.

If you change the radiator pick up your hoses at the dealer. They look better than the goodyear ones on put in my XJ in 2000. In Feb this year I installed the dealer hoses, they have the antichafe on the outside and a full length spring on the inside of the bottom hose.

Sounds like it's time for a cooling system renewal, also make sure your electric fan is plugged in. Don't ask me how I know that lesson :)

Yeah, neglected cooling system would have been the previous owner. I'm sure I wouldn't have been much better though.

I'll pursue a new thermostat from the dealer, and then follow up on the fan clutch, and then I might pursue a new radiator.

I appreciate everyone's valuable feedback. It is really helping me understand the cooling system and put everything into perspective.

What about a pressure problem? If I understand correctly from other threads, it could be something as simple as a radiator cap - although there isn't much to outwardly indicate there is a pressure problem, I suppose it is possible.
 
The radiator cap is an often over looked component. The radiator cap increases the pressure in the cooling system which allows the coolant to hold more heat (BTUs). Coolant at 16 psi will hold more BTUs than the same coolant at atmospheric pressure. If the radiator cap is releasing pressure before it's rated pressure then you will be running warmer just cause of the radiator cap.

The general rule is if you have an overheat then you need to change the thermostat and radiator cap. High temperatures can damage both items. The spring on the radiator cap can become "weak" once it has seen high heat.

Replace both and that may solve your problem but still think fan clutch and radiator are contributing to the problem.
 
I was telling a buddy about your problem and how you had brown coolant. He said you could have a leaking trans cooler in the radiator, that could explain the brown color coolant.

How has yout AFT level been in the transmsision and have you been adding fluid? Does ATF fluid have a different color?

Just a thought, hate to have you burn up a transmission.
 
martin said:
I was telling a buddy about your problem and how you had brown coolant. He said you could have a leaking trans cooler in the radiator, that could explain the brown color coolant.

Thanks for asking around for me! I'm still scratching my head about the problem until I can spend more time under the hood.

I'll have to check the trans fluid level. Its possible that the trans cooler is leaking, but my last 95 XJ was a 5 speed, and it had discolored coolant just like this. It formed a little bit of sludge at the bottom of the reservoir. I think its just "dirty" (rusty?), for whatever reason - probably neglect. I'm not sure.

I bought the Cherokee at 75k (101k now), and I was under the impression it was well taken care of - service records in the owners manual up to 61k and everything. The only cooling system service I found was the waterpump - the very last record at 61k.

Since I just replaced the water pump at 100k, the coolant seems to be staying relatively clean, but time will tell.

Thanks again, Martin! :)
 
I changed the whole cooling system on my '96 last summer after blowing out a water pump gasket going up to the Sierras the day before the fourth of July. Solved all of my overheating probs. The only time I can get it to hit the 210 mark or a little over is on my commute home from work. I have to pull this steep hill in the afternoons. It will stay at temp just fine on the way up, but after I crest the hill and the RPMs drop from 3000 to 1200 as I coast down the other side it will spike for about 20 sec. and then go back to temp. I always figure it was just the water pump slowing down and not dissapating the residual heat fast enough. I would say that at 100k, just start at one place and start replacing things. You'll end up doing it soon enough anyway, and it is better to do it before something goes wrong.
 
Going to the beach in NC tommorrow - 7 hour drive. Wanted to take the XJ, but its still running hot. :tears: Have to take the Forester instead and see if my folks will let me use their Libby in 4WD access areas. :banghead:

I replaced water pump, lower hose, thermostat twice, radiator cap, and flushed coolant. Electric fan comes on properly. Temperature goes down when I turn on heat. Overall, the system seems to be functioning normally.

Keep in mind, this is a stock 96 XJ that seems to have been clean and well kept, and has seen very little trail duty.

My best guess at this point, its either the fan clutch or the radiator.

I'm suspicious of the fan clutch. I put a dollar bill against the grill, and I could feel the pull of the mechanical fan, but the electric fan felt somewhat stronger. Is this right?

In any case, its around 80 degress in PA. I let it idle in the driveway for about a half hour with the A/C off. Electric fan came on around 217, and the needle seemed to stay around 230, I think - or just less than the 1st bar above 210. Then I turned on the A/C, and let it sit for 10 more minutes, and the needle worked its way into the lower red.

I'm sure I can maintain lower temperatures while actually driving the Cherokee, but I don't want to risk a long road trip - especially to a slightly warmer climate.

What do you guys think? :)
 
I would go out and replace the fan clutch today. Those seem to have shorter lives than radiators. I hear to expect 5 years out of a fan clutch and 7 years out of a raditor, if you have more than that you just got lucky!

I would then do your test again. It may run cooler than you described. If so then I'd take it with you on the trip.

The other thing to do is to go out and get a new radiator and a new fan clutch and install both and fill with new coolant. This would be a 3-4 hour job for the first timer. You would have it all renewed.

The kicker is the long trip tomorrow, there just not enough time to become fully confident in the repair.

If you are taking your other vehicle then wait to work on the XJ until you have returned, enjoy your time visiting.

PS when you do replace the radiator and clutch see how it works, see if you are running a few degrees warmer. With a thermostat that seen high temps is may open late and close late causing larger swings in temperature.
 
Drain the coolant, refill with tap water, dump in a pint of Preston 7 hour flush, drive to NC and install the Prestone back flush kit, flush the cooling cleaner out and refill with coolant and distilled water. Go from there.
The procedure for testing the fan clutch is to drill a hole in the fan shroud, stick a top read thermometer in the hole so that it is in the fans air path. Watch the temp, it is supposed to go up and down as the fans clutch engages and disengages.
 
Rich, you are a veritable wellspring of info. Do you agree w/Martin on the 5 yrs. for fan clutch/7 yrs. for radiator?

When I had the exam & tuneup on my "new" '96, I specifically asked them to flush the radiator if necessary. They (a famously reliable garage) said it looked great & didn't need flushing. How did they know this? Do they have some way to test the coolant?

When should I have it checked again? How can I monitor my radiator's health myself? Do I have to wait for the car to overheat before I know something is wrong, or should I do as Martin suggests & just replace the whole system as preventive maintenance? What's an average price for having that done?

Does the DIY flush you suggest help prolong the life of the radiator?

(I've got to stop browsing around finding new things to worry about.)
 
Okay, guys. I'm losing my mind - I'd love to simply turn the XJ over to a shop and let someone else deal with the running temperature problem, but I just can't afford that.

Things that I've done:
Replaced water pump, thermostat once, thermostat twice, radiator cap, fan clutch, and lower hose. I've also flushed coolant twice.

My old fan clutch did indeed seem to be shot. Once I removed the fan assembly it spun very easily in my hands with some initial resistance. I would spin it, and it would go round and round.

Last weekend it was around 90 degrees here in Pennsylvania, and after a relatively short drive halfway across Lancaster County, it was boiling and throbbing. I haven't driven it since, but today, I discovered the radiator was leaking very much coolant - possibly due to the near overheat this past weekend. The leak itself seemed to be on the very bottom right - perhaps at a seam.

Despite the leak, I ran it for a little with the new fan clutch and it still creeped toward the red, even through its a relatively cool night.

What is left for me to do? ... replace the radiator?

What kind of radiator should I put in its place?

How difficult is a radiator swap? (hours)

Could anything else that I haven't replaced be the problem?

Thanks for any help you guys can provide me with. I just want the XJ to run cool again.
 
You mentioned that your rig seems to be worse after the water pump change. I know my 98 XJ requires a reverse rotating water pump, and the FSM warns that some earlier models used forward rotating water pumps. Could the garage have made a mistake and used the wrong water pump?

-Chuck
 
Chuck_SA said:
You mentioned that your rig seems to be worse after the water pump change. I know my 98 XJ requires a reverse rotating water pump, and the FSM warns that some earlier models used forward rotating water pumps. Could the garage have made a mistake and used the wrong water pump?

Thanks, Chuck. I sent an inquiry to my parts salesman. He's got his act together, so I doubt I got the wrong water pump, but its possible!

In addition, I'm pretty sure I had this problem last summer too. But then it got cold out and I forgot about. Now its getting hot again, and it seems to be coming to a head.
 
I didn't read every post but I have 2 96 XJ's and both have had to have new 3 row radiators and clutch fans. That fixed both of them.
 
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