was that the electric fan or mechanical fan?
Mike

 

the electric

 

No it's a single speed. Do you think it had been running but had turned off and was just spinning to a stop?
How hot was the air temp when you did this?
The not so good news is if your Cherokee is just sitting there at idle it should not get that hot unless your in the desert.
We still have a problem then. What did you find out about the lower coolant hose? I believe you said you could squeeze it so we know it doesn't have the spring in it. Have you changed that yet?
Mike

 

Well i stopped it with my finger when the temp was at 220. when i let go it started spinning at that same slow speed. after i changed the temp sending unit last night it was moving really fast. but have not checked it this morning.
i called the jeep dealership yesterday evening and they told me the hose was in, i asked them to check to see if it had a spring in it. he said it was soft when he would squeez it. i told him that was the wrong one so i didnt waste a trip to pick that up. has there been an issue in the past with trying to find the correct hoses for the xj's. does anyone know of a place online i could order one that is deffinetly the right one? all the local shops around me have the soft hoses. as soon as i get a good hose i will do the complete flush on the system. i dont want to do those at different times bc i dont want to waste the coolant.
oh and about the desert, it feels like the desert down here sometimes

 

He should be able to look inside and see if has the wound spring type reinforcement. At least mine is that way. Did you watch the lower hose to see if it's collapsing when this happens?
The fan thing has me stumped. Maybe someone else has an idea. Bad ground? Contacts in plug are not making good contact? People have posted things in the past about checking those electric fans. I ran mine without one for a year and never had a problem getting hot. Many others have done that also. While a proper system should have the electric fan operational, you should not get hot enough to have it kick on at idle when your just letting a cold engine warm up to temp.
I say we wait until the correct hose comes in so we can take that variable out of the equation. Then tackle the flush and fan.
Mike

 

yea that fan thing is wierd. here is what happened yesterday. i tried to duplicate the overheating so i could run under the jeep and look at the radiator hose right at the time the temp would spike to 250 or so. after 15 to 20 minutes of idleing around off road the temp would get to 215 or so. it didnt spike. well i went into town from there and from the stop and go traffic the temp would rise to 220 (that is the knotch above the 210 mark right?). i knew for sure it was going to spike at any time, but it didnt. so i didnt get a chance to check the hose bc it didnt spike, i will try and dup it agian.
Maybe this is whats happening ( just a hunch ). tell me if i am stupid or not. the hotter the jeep gets the more the lower hose constricts causing reduced coolant flow, until eventually the hose collapses causing no coolant supply to the motor and the temp to spike.

The new correct hose will be here tomorrow

 

You shouldn't need to go up to 220+ to see the hose collapse. It should start to collapse as the stat starts to open around 195... Since the stat opens slowly it should collapse more and more as it heats higher. But yes, I'm sure the hotter it gets the more flexible the hose gets and it would tend to collapse easier.
What are you planning on doing when you get the new hose?
Flush everything? Put a new 195 stat in or check your current stat... Give the run down in detail what you have learned so far... We don't want you to miss something so you are successful.
Mike

 

Mike get this,

Like i said earlier i changed the temp sending unit and the fan went from being slow to fast. it seemed like the temp was running about 20 degrees cooler. i got about 2 miles from work and came to a red light. the temp slowly dropped from 205-210 to 100 and then the check engine light came on and the engine died. it cranked back up but the temp guage was not working. i made it back to work and looked under the hood. i knew that if you dico'd the TSU while it was running then the CE light would come on. i looked at the TSU wiring connector and found the wires loose coming out of the connector. i wiggled the wires and the temp guage started working agian but was running at 220 and the aux fan was moving very slow agian. i played with the wires some more and the guage went back down to below 100. so i know the wiring connector is causing the CE light but not sure about the jeep dying on me. When i was looking at it back at work it would start and idle fine

Now here is the kicker!!! now when i turn my A/C on the aux fan will not come on.

I am starting to see her ugly side



So here is the list of what i has been done
1. new water pump.
2. head has been rebuilt (oil looks fine and no leaks)
3. new radiator
4. new hoses
5. new 195 t-stat
6. new temp sending unit (the thing on the t-stat housing)
7. new 16 psi radiator cap


My plan in the next couple days

1. Replace lower radiator hose
2. Flush
3. i need to check my aux fan radiator somehow

Thanks Mike and anyone else that can help

 

Just replace that fan motor. It is getting hot and hot motors have more resistance and thus will run weaker. It is tired, time to retire it. Once you do, that will take care of a lot of your overheating issues. Replace your lower hose and you should be good to go.

 

Thanks i will get one from advanced this evening. do you think i sould check or replace the relay. i hear the one from the dealership is like 80 bones and the ones on the shelf at the parts store dont work.

 

If you have a ohm meter you can check resistance across the contact points when activated or voltage when activated. If the voltage drops across the contacts, then it needs to be replaced. I don't have a 4.0L so I don't have the relay to mess with, but for that much I would just wire in an aftermarket relay in its place. They work on my fans.

 

What's with the Mike get this? Do you think I'm going to read through your whole post everytime I look at it? I was asking you questions about the hose collapsing that should have been answered a week ago. I don't see where I asked you anything about the temp sending unit. Personally, I can't believe after a week you still haven't gotten a diagnosis on the hose collapsing or not! WTF
Good Luck.
Mike

 

well until the last post you were the only one in a while that was continuealy giving me good advice.

i guess this forum is a little diffrent than tacoma world. i need to get use to it

I have checked the hose many times to see if has collapsed but never at the time the temp spike to 250. i didnt know until you posted two times ago that it could be collapsing around 200. well its not collapsing then. i am still going to change it. I changed the eletric fan and this one runs a heck of a lot faster than the last.

 

Thanks for the advice, i guess i always saw then fan running but since i have never had a aux fan on a vehicle, i didnt know how fast they should spin or when they should turn on and off. this new fan is fast and pulls a lot more air i will check this tomorrow to see if it makes a diffrence

 

Couple years ago, my "parts house guy" told me to use the relays for a Subaru instead. $25 a piece, same resistance and all that...I changed out the relay, been working fine since then. Hope that helps a bit, warthog.