Jeep Cherokee XJ 2001 mini heat spike overheat check gauges quick recovery to 210F

Maintenance/Repairs
1

I had a question about overheating in my Cherokee. It’s run very well since 2014 through ~ 2023 with regular maintenance and all needs addressed promptly. Always running at 210F or less. Since a shop ~ 2023 it stays higher than 210F all the time after warmup and has heat spikes at the top of long hills or load shooting to 235 with check gauges. I turn it off with the hood up and then key on with three electric tans that cool it rapidly to 210 which seems impossible for it to climb fast and drop fast but has been reproduced and verified with a heat gun.

Thoughts?

2

Welcome to Car Talk…

Since this all started and has been a consistent issue since a shop visit 3 years ago, it might make sense to explain what was done to the vehicle and what the reason for the repair was back then…

Example, if a thermostat (t-stat) was replaced, was it due to overheating, or something else??

Questions:

What is the in-cabin vent temp when at normal operating temp??

Is the coolant full in the radiator and not just in the overflow tank??

Have you double-checked the temp at the t-stat vs. the live data ECT temp vs. the dash gauge?? They should all be moving together…

Have you checked for a blown head gasket?? block test??

Lots of possibilities, such as a restricted radiator, t-stat not opening all the way, bad fan clutch and/or electric fan(s) operation, radiator cap, air pocket, etc., etc.

3

Without any more information, your description suggests a partially plugged radiator. Has the car been behaving this way consistently since the shop visit 3 years ago? What did they work on back then?

4

You could be getting a collapsedlowervradiator hose too. One thing i had that reduced the radiator efficiency was bugs on the radiator. Pressure washing took care of it.

5

Wow thank you for the support and responses!

A - the visit three years ago was not very eventful. Oil change and coolant flush where they brought up wanting to back flush the heater core. The thermostat at that time was 180 F with zero issues and formerly a 160 F because I can’t stand driving it in the summer. Once it gets over 180 it’s like the firewall becomes heat rocks and then when the heat transfers to the transmission. Not my fav. AC has always worked and I’ve rebuilt it entirely twice all parts replaced.

B - vent. I almost never use this. Answer would be a guess. I use AC or windows.

C - Coolant is an interesting question. I’ve had coolant in it last month July that was designed to run at a lower temp which did nothing. In 23 and prior never any coolant loss. What is it in the radiator? I have no idea I’ve never uncapped it sorry. Coolant in 2026 Apr May Jun Jul Aug is a problem. I’ve been adding a gallon of coolant between oil changes. This is communicated to most recent shop since 23 after what I’m going to call an incident.

D - have I double checked the real temp vs the dash gaugee to see if they are in sync? No. But the temp sensor the shop is insisting is correct because they verified with a heat gun. That the temp is real. It’s really 235 or 240 or whichever it actually is and by miracle to me, drops fast as it went up. As far as live data they have had all kinds of that equipment connected.

E - I am not sure what a block test is but the motor was rebuilt by most recent shop. ~ $4000 because of the incident. If that means freeze plugs I guess they made sure they are sealing.

F - Blown head gasket. To me. I think this is close to what it is. Shop owner is of the religion that if no white smoke is coming out tail pipe and no carbons showing in test of overflow tank. Good to go. I have asked for compression test with no answer. While the head was off during rebuild they ran some kind of test. Name is out of my head right now. It’s supposed to reveal flaws in the head. It passed. They said the head was not warped. I believe them on these points. I do not trust the head, however. Is my personal gut take.

G - I love the radiator question. I’m on radiator #6 in three years. Miles I’ve driven can’t be more than 5000 in same years. Vehicle lives in shop. I’d prefer it is a daily driver. It’s garage is the garage. Have all radiators performed the same? Essentially. Most luck we’ve had after the giant metal fan is we are now on single core aluminum with three electric fans. I prefer the electric fans stay on until I die. The mechanic who has done most of this is Rob who has retired or quit. So I have to deal with the owner who wants to start over at zero. Back to OEM. I’ve owned many Jeeps. All perform mostly normal. Even this one until the incident. With OEM mostly except NGK Iridium plugs and 180 thermostat.

H - Thermostat is on at least #3 in three years. Currently as of Friday a high flow double cubic feet water pump #3 which speeds up the flow until 3500 rpm and then runs normal. I think it has a 195 back it same brand as high flow water pump. It is now for the first time in three years staying just over 200 F at 208 I think I was told Fri.

I - fan clutch was blamed and crucified first with a whole burning and celebration that must be it. When it wasn’t we tried two different giant metal blade fans. We moved out of that solution because when the engine torques going around the corner the metal blades cause the entire front end to jump as the blades separate the radiator like Baraka on Mortal Kombat. That entire six months of trial and error are a special layer of ■■■■.

J - Thank you for asking on the electric fans. The 00 and 01 Jeep switch the OEM fan on and off with or without AC at about 180 small periods of on and then off building up to hotter temps where the OEM fans would really blaze for a bit to calm down the heat. I love the three electric fans. Except. I want the third fan to not be wired at 218 F. The owner is fighting me. Says the computer will have issues if the fan comes on earlier. My guess is he means the live data says engine runs cold. I’ve run 160 F. I don’t care engine runs cold. I don’t miss 2 MPG. Point is I’d like that fan to come on at 200 or 180 or 160 or always. I’m afraid I’m going to have to peel my jeep out of the clutches of this place and part ways if I can’t have my win here. I can’t explain enough how much I hate to one million a 218 third fan. If we are reproducing OEM 218 is not it. Maybe a 1999.

K - I’ve requested my aluminum single core radiator cap replaced twice in the past two weeks to no response. The radiator is newish and of the six it has run since the incident they all do the same thing.

L - air pocket — the thing has been burped more than any infant gets burped. It’s had its coolant changed fully at least three times in the past three months.

M - I’ve brought up the spring in the hose possibly ten times. Each time I’m met with new hoses do not come with springs and they are made in a way to prevent collapses. So I ask. What if we get a spring from an old hose and use it. This is always brushed off as I don’t know what I’m asking and it isn’t going to be done. Also. I’d wager I had a spring three years ago after the incident.

N - the incident. Is. I believe a boy right out of high school was working my Jeep oil change and coolant flush. In the process he punctured my favorite of all my radiators an aluminum one. Under lifetime warranty which I still have. Outside the Jeep now. I believe theoretically he told no one. Because they make him replace it. Meanwhile while the unpressurized system ran. I theorize he ran my Jeep to the temperature of ■■■■. And told no one. And they swapped the radiator they said and said I was good to to go. The end of the Jeep really happened in that shop on that day. It’s never been right ever again. It can’t run right. Can’t cool right. Misfires.

O - Misfires are a consistent code. The most recent oil change I brought it in for in July and have not got it back it had four coolant leaks. Four misfire cylinders. So. The misfires are this. 91 octane gas mixes with air into my replaced and cleaned injectors. According to my theory / belief: Problem 1 is champion plugs don’t burn well. Problem 2 is not burning causes extra heat. Problem 3 is extra heat takes temp over 212 which boils the fuel contributing to 1 and 2. Combined together is misfire on any cylinder. Always over 212. This entire misfire section I resolved the second year I owned it with NGK Iridium plugs. Never had issues again with misfire. When shops take me to champion iridium or copper. I get pretty **** well I’ll let you fill in the blank.

Thank all of you for your input!

6

Check the radiator for missing fins. They corrode away with age. Pull the fan shroud away from the radiator after removing the screws at the top. The shroud sometimes hides the worst of them. If you look at the radiator and you see green or white coloring just get a new one. If running the heater full hot and high fan speed helps then a new radiator could be the perfect solution.

7

He’s on radiator # 6 now.

8

Just throwing out an alternate viewpoint here…

I’ve been driving over 30 years now. Only twice have I ever had to have a radiator replaced, and both of them were Chrysler/Dodge/Jeep vehicles. So in my experience, replacing a radiator is pretty rare. You’re apparently on radiator #6 with this Jeep.

It’s also 25 years old, and it sounds like it has some other “25 year old Jeep” type issues.

Is it time to put this horse out to pasture? :grimacing:

9

I would have dumped this Jeep long before it took a post the length of a city block to describe the problems.

10

Does this Jeep have an automatic transmission?

The coolant is obviously going somewhere . . . has anyone verified it’s not finding its way into the atf?

11

Four coolant leaks? Where? Have they been fixed? As far as spark plugs, use OEM plugs. If this were an AMC Jeep from the 60s, yes you could play around with different plugs but not on your Jeep. .

12

You never check the coolant level in the radiator? How can you be sure it is full? If the cooling system is low, this will cause the temperature swing you observed.

That is a significant coolant loss, if you don’t see or smell coolant leaking, the problem may be a leaking head gasket.

Blown, no.

Leaking; possible. When a section of a head gasket is “Blown” out, there is a continuous compression or coolant leak/loss. A leaking head gasket can result in coolant seeping into a cylinder under certain conditions; only when cold, hot or under high pressure. You would observe a coolant loss over a period of time.

After they refill the cooling system, does the engine overheat the same day? Or after several days of driving, after the coolant level becomes low?

Four misfiring cylinders? Is there evidence of coolant in the cylinders?

Misfire problem solved. This is confusing.

13

1st off, thank you for the very detailed post, it answered most of the questions I had, and was easy to read/understand… The more info a Pro mechanic has the better the help we can offer…

+1 for Nevada’s post, covered pretty much my thoughts at this time…

I will add to Nevada’s leaking (not blown) head gasket theory, especially after reading the engine was “rebuilt” for $4,000 since all this started, being “rebuilt” doesn’t mean the block and head was sent out to a machine shop to be decked and checked and magnafluxed to check for warpage and or cracks…

You might/possibly have a cracked head… Your XJ engine from late 1999 to early 2002 are know to crack between cylinders 3 and 4 (IIRC)… I think it is called the 0331 head for the casting number(?)…If so, those heads will crack even with a minor overheating event… And you sound like you are way beyond a minor overheating event…
Yes the coolant flush done improperly could be the root cause and failure to this whole event…

14

Yep, I think one of the past writers at Jalopnik discussed this. Here’s more from an XJ site:

Jeep Cherokee 2000-2001: Cracked Cylinder Head Information | Cherokeeforum

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That’s a pretty good article, imo

16

XJs have quite the following. We had ours for 12 years in Anchorage, perfect for up there. Amazing amount of room is such a short vehicle, too.

17

Not sure why you tagged me. I only condemned the Jeep in this thread with all the problems it has.

18

Not being critical, just saying this 25 year old vehicle is valued by lots of fans, unlike most 25 year old vehicles.

19

Agreed, and it (the OP’s) was the last year of the real Jeep Cherokee’s, unlike the c.r.a.p they are making now… imho

20

Thank all of you for your helpful replies.

Nevada, I mostly agree with what you are saying. I will start checking under a cold radiator cap before starting when I check the oil. Which is almost daily in any XJ. This is my third XJ and I have maintained four Grand Cherokees. All of them have a list of pros and cons. This 2001 XJ is .. possibly the most expensive to maintain vehicle I’ve ever owned more than a BMW. However the newer Grand Cherokees when they have a problem are $3500 - $8500 a shop visit so that is the end of that vehicle. Won’t buy another Chrysler after 2010 if it is close or over 100k miles.

When does the 2001 overheat? The day I get it from the shop. In the summer one can enjoy the ice cold AC because the load moves the needle over 210. Over 210 brings heat to the cab. After an hour of driving a day it’s unbearable. AC risks high temps under the hood that once over 210 can spike to “Check Gauges”

If I’m trying to drive up not the steepest kind of bill but gradually up into the higher streets with the AC on I can bank on a “Check Gauges” stop. Hood up. Key on. Fans drop the temp to 210 within 30 seconds.

This is repeatable and the shop repeats it and with a heat gun cause I was saying I didn’t believe the sensor and questioned if it needed replacement.

The shop owner has insisted in my lengthy friendly discussion with him where my Jeep has lived there 75 percent of the last two years since he was taking over the work, he was insisting white smoke needs to come out the exhaust to suspect the head and there are no carbons in the coolant.

He was intent on bringing the electric fans and single core radiator back to stock which was square one when it came in with overheating that caused more problems resulting in rebuild. The sleeve came off one of the pistons. Now should I have read that as the last sign and drive it to junkyard? Possibly yes. I looked at Jasper for $3000 and the reviewers said they wish they had rebuilt what they had for $1000 more so I did.

I agree I usually change one radiator about every six years maybe. What’s changing radiators are more accidental holes while in the bay. Or config changes to cool it different or more cores or aluminum or metal fans. We’re on the fifth idea in two years. Six radiators.

The four coolant leaks was a real surprise since everything was redone under the hood. My suspicion is the higher temps cause the hoses to need to be addressed where they clamp. The four leaks are addressed. I’m sure when they were leaking that didn’t help the temps in yet another circle.

The misfires I could make a whole thread on. This Jeep has misfired from the day I bought it for two years no matter how many injector cleans, plug change, fuel brand change, nothing helped. So I decided. Put NGK Iridium. The shop I did that at worshipper OEM as the creator and put Champion Iridium which coded. I went to a new shop and got NGK Iridium. It never spark plug misfired again. Until the incident. In the rebuild the machine shop installed a new oil pump, water pump, champion copper, 195 thermostat I hadn’t had since before I got it, and other new parts.

The head was ensured it was not warped. Additionally they performed a test. It has a name I’ve forgotten but it is supposed to reveal defects. In the head. Which it passed. However I have lost faith in the head where the coolant system has been recreated so many times.

I appreciate the attention to the spring and collapsed hose but I’m assured there is no spring and I do not need one. I don’t feel assured. But for the moment I’m going to file needing a spring with older hoses that require springs so they come with springs. It isn’t my religion. But I’ll tolerate it for today.

The high flow water pump is the first giant progress it has had in two and a half years.

But I agree with you Mopar guy. I bet it is 0331 head and I bet it overheated to crack in the incident of first punctured radiator. In that shop. They gave it to me but it was passed away. I been resuscitating a zombie vehicle from that day I should have let it pass.

I agree. But consider. It should just be another few hundred dollars and that will be the fix. Then you’re a ways in so you rationalize another few hundred dollars. I’ve learned and now others can learn from me.

Sometimes a city block of life happens to a person. Sometimes that needs to be in a community so others can help (thank you!) and others can learn from it. I hope for all of you a city block of problems don’t happen to your vehicles because it costs a few vacations you won’t be taking.