MsMassakre

Hey guys, recently got my second xj and noticed it's running a bit hot. Looked and the electric fans not turning on. Fan spins freely, tested the connector to the fan, relay, fuse, all work. Went as far as using a Modis and running it manually, worked just fine as well. Anybody have any experiance with this issue? 2000 Jeep Cherokee classic 4.0. Any input appreciated, thanks!

extrashaky

"Running a bit hot" is a little vague. The normal temperature range is about 205° to 220° F. If you're not running above 220°, you're not really running hot.

Regarding the fan, the behavior of the electric fan changed in 2000, which often leads to posts where people think their electric fan isn't working when it is. In the 2000 and 2001, the electric fan doesn't come on until the coolant temperature reaches 221° F. Then it stays on until the temp drops to 217°.

The electric fan also does NOT come on automatically when you turn on the air conditioner like it did in the '99 and earlier models. In 2000 they changed it so that it doesn't come on until the high side of the AC system hits a certain pressure.

So. Are you sure the fan isn't working properly?

MsMassakre

I honestly got scared to let it climb much past 215. My bf is a certified tech, awesome at what he does and has been jeepin way longer than I have. He said running at 210 was too hot. I have a 98 zj 4.0 for 4 years and told him I had put 100k on it with no problems at all, never broke. It runs at 205 210 the entire time. I know about the head issues w the 2000, 2001 xjs so I'm a bit worried. It's at about 205, 210 driving but after a bit climbed to 215 at idle. I will try to get it to climb to 220ish and see if the fan kicks on, it just seemed too hot to me. Thank you for the input.

extrashaky

He's wrong. 210° is the exact middle of the gauge and the spot these things are built for. A lot of otherwise knowledgeable people are surprised to find out how hot these beasts run.

215° is not going to hurt it. Like I said, the electric fan isn't even supposed to come on until you get up to 221°. The designers wouldn't have waited for it to overheat before kicking the fan on.

MsMassakre

Thanks extrashaky. I just assumed it should come on at about 210 because my zj never climbed past that idling in 100 degree weather. Everything in the circuit worked, including the fan when manually run, so was hoping it's not the ecm failing to send a signal to turn it on. My other 2000 xj had a stuck open thermostat so it never climbed above 160 sucked a bit on those cold mornings at 6am haha

BlueRidgeMark

Well, then he's not as knowledgeable as the two of you think he is.

He's just flat wrong. 210 is just fine. It's in Happy Jeep City. Running as designed. Doing the right thing.

Stop trying to make it run out of spec.

MsMassakre

Not trying to make it run outta spec. Like I said, my grand cherokee ran at 210 for 4 years and 100k miles and all I ever did on it was an o2 sensor and a crank sensor. I know it's not the same car but still a 4.0 so when it crossed 210 I got a bit concerned knowing the cracked head issue. But hey, I'm not too mechanically inclined, try to search and read what I can so I figured I'd post a question. Sorry?

Firestorm500

Your Jeep sounds normal and fine. Doing exactly what it is designed to do.

I don't think that, now and in the future, you should compare your XJ behavior too closely with the '98 ZJ you used to have. Similar, but different vehicles. The XJ changed a lot in 2000-01 from the way things were previously. In fact, they changed a lot in '97 while your '98 ZJ was the last year of the first-generation production. It was essentially using old technology at that time.

I would also observe that bf means well, but before he starts throwing around unfounded opinions on what is and is not correct, he needs to do some research first. No one can know everything about everything, and be correct all the time. In this case, he is just flat wrong. He would be wrong if we were talking about a '92 XJ 4.0.

If your gauge needle ever jumps over to the red zone, then it's way too hot. Minor fluctuations are expected. Don't fixate so much on gauge movement that you are driving distracted.

extrashaky

Don't get upset. We get quite a few posts on the board where people just can't believe that the 4.0L is supposed to run that hot, even after a dozen of us chime in and say it's normal. It's not uncommon for someone to be so completely unconvinced that he or she starts replacing parts that don't need to be replaced or trying voodoo cures that usually make things worse, even after a bunch of us have said it isn't necessary. Because that happens so often, it becomes an automatic response when this topic arises to think, "Oh, here we go again." Mark was probably reading a lot into your post from all those earlier conversations.

Regarding your 0331, it's good that you're aware of the issue. The problem with that head is that it will crack if it feels like it, not necessarily because it was overheated. So while you shouldn't worry about running at 215, you should be prepared to replace that head if any of the regular symptoms of a head crack show up. Those signs include drop in coolant in the overflow bottle that can't be explained by a visible leak, bubbling/boiling in the coolant bottle, intermittent jumping of the temperature gauge into the red, red mud collecting under the radiator cap and in the overflow bottle, coolant in the oil (detected by a used oil analysis, NOT by eye), and even a visible crack in the head that can be seen directly under the oil filler cap by shining a light down in there.

In other words, don't let it worry you, but just keep an eye on it.

MsMassakre

Thanks for the respectful responses guys. I don't even have carpet in there, the floor got wicked hot, jeep smelled a bit burny that day for lack of a better term and coupled with the head knowledge and that I've never seen the other 4.0 jump over 210 I got a bit concerned it wasn't working correctly, it was my first long trip with it. I didnt post without looking through the forums, searching online, and testing though
We busted out the wiring diagram and traced everything, everything worked, like i said even the fan when run by the modis so that's why I was confused as to why it wasn't turning on. All his xjs were pre 98 so I'm sure that's where he was confused too. Side note, we were at 95 in the south suburbs of Chicago yesterday, I purposefully took side streets to sit in some traffic home from work and she still never climbed past 215. Down to 205 210 when cruising. I try the best I can, I absolutely love jeeps and feel bad asking my bf constant questions or for help every single day (he spent a whole week fixing it up for me when I bought it) so I appreciate the responses and info and opinions/experiance. We will do a coolant flush and not gonna worry about it too much anymore unless it gets way hotter.

jamesh

hi , can you help me here whit something about a 2000 jeep cherokee 2.5 cooling fan?
I rebuilt my engine last mouths and im starting the engine this days but i see my cooling ligth always on and i guess its not cause miss coolant since i had add , and then after i turn on the engine the fan is always woarking and dont stop , only stop if i turn off the engine ....today i had the engine runing about 10 minutes and she always on and i think i saw some smoke around the radiator so i stop the engine....iom not seeing where is the problem or if i did something wrong there. Sorry my language im portuguese

Larry's XJ

It's good that you are concerned !!!
From what I have seen on here is that the gauges/ and or sending units will win no awards for accuracy. You could double check with an IR thermometer.

MsMassakre

Idk man. Have you checked for any leaks in the radiator? If your fan is constantly running and you still overheat it has to be something with the engine not receiving coolant. Cracked head, radiator, thermostat? Have you actually verified the temp, maybe your gauges are somehow off?

MsMassakre

Thanks man. I was just a bit concerned because I was comparing to my 4.0 in my zj. That one never went above 210. My xj crawls around 215 buthe idling at 100 out with ac blasting I finally got the fan to turn on and can confirm it works just fine. Just wasn't used to it turning on at such a high temperature and I know the 0331 head issues so got a bit worred. Everything fine now, wheelin or driving. Thanks

Pitchel

Hey guys - my 1998 has almost the same condition. Other posts helped, but did not answer all the questions - hope you can help. Here is the detail and what I have done so far...


A couple differences from MsMassakre - mine is a '98 and my typical temp gauge stays right at 210F. Last week (90+F ambient), I got caught idling in traffic for ~15 min. The temp gauge rose to the edge of red and the red "Check Gauges" light came on. Traffic cleared soon after and 1-2 minutes of driving had the temp back down around 210. AC blew cold the whole time (turned it off when the temp rose), and turned back on when it dropped. At least that made me feel good about the cooling system. Fan Diagnostics:


1. Confirmed mechanical fan clutch good = noticeable airflow jump as temp increases.
2. Confirmed electric fan bad = sent 12V directly to fan connector. Removed and blades difficult to spin (ok - bad motor).
3. Installed new fan - confirmed function and polarity (based on other threads) before install.
4. New fan did not turn on in vehicle. Testing = idle in driveway until coolant reaches 210 and turn AC off/on.
5. Confirmed temp sensor good = IR gun & temp gauge <5F apart
6. Checked fuses = all good
7. Checked relays - swapped starter & e-fan relays = vehicle still starts
8. Checked voltage @ wire harness connector = 0V under all conditions. (Might not matter, but the very first voltage check before pulling fuses/swapping relays the voltage read 0.8V with AC on, but all later checks read 0V).


Any suggestions thoughts - did I miss/mess-up something? Based on the detail in thread, if mine was a 2000+ it might be ok, but I would like have more confidence before getting caught in a bad spot again. Is there a better test to confirm voltage is being sent to the fan? Thanks.