Hey All,
I am brand new to jeeps and this forum. Just sold my 03 tacoma 4wd and bought a 98 xj (always wanted one).
Now my question along with many more to come most likely is that i will be running at around 210 and all of a sudden the temp guage will max out at 250 or 260 for a couple seconds and then suddenly drop back down to 210.
Now i know that liquid cannot cool down that fast so i am wondering what is going on. i have read a lot about xj and know they have an overheating problem.
the radiator water pump and hoses are new he said. any help.
thanks in advance

 

try replacing the temp sensor which is located on the t-stat housing. are you leaking any anti freeze anywhere?

 

If you see repeated overheating problems (even after replacing the sensor), there are colder T-stats available. Stock is 195, but you can get a 180 and a 160. Be warned, however. Running too cool will decrease gas milage and increase emissions. I wouldnt suggest going to the 160 unless you have real problems and live in the desert.

 

Do a search on this forum... You will find all you need to know about running hot and how to diagnose the issue. The last thing you want to do is to replace the thermostat with a 180 or 160. Find and treat the problem. If you suspect the thermostat you can take it out and test it or replace it. The first post sounds like a good place to start, "Loose plug to sensor or sensor".

 

not leaking anything. i will try the t stat first then the wiring. i am thinking it has something to do with the wiring or the connector.
thanks

 

I would only put a 195 T-stat in. Throwing a 180 or 160 in is not fixing the problem, and probably wont even mask it. Replace with a 195 T-stat and replace the sensor to see if that helps.

 

and if that dont help, replace the fan clutch and flush everything out and fill it with water and coolant, i had this exact same problem like 2 days ago and this fixed it, i live in alabama so i know it can get really hot

 

"the radiator water pump and hoses are new he said. any help."

I can't remember which of the 2 hoses coming from the radiator are supposed to have the metal windings inside them, that don't allow the hose to collapse. I don't have my Cherokee with me at this time, maybe somone else can check theirs and post. If he put a super cheap hose on it without the inner metal winding it may be collapsing when the thermostat opens and not allowing the coolant to flow. Squeeze the 2 large hoses and see if they are ridgid... Sorry, I just can't remember if 1 or both are supposed to be... Someone else will help us on that.
Mike

 

If you're running at 210 and then it all of a sudden spikes to 250-260 then goes right back down to 210, I would bet you have air pockets in your cooling system. Run your Jeep with the radiator and overflow cap off until normal operating temperature...and you can look in the radiator and see coolant circulating. Top the radiator off and continue to watch it for about 5 more minutes. Top the radiator off again and install the cap and then fill your overflow to the HOT line and install it's cap. See how it runs.

 

If you do what Buck said you'll have to have someone hold the throttle around 1500-2000 rpm's while you run with the cap off. And while you screw it on... carefully with a leather glove on and a rag over the cap!
Others swear that these systems are self bleeding when it comes to air and that is unnecessary... I always do it that way and burp the radiator hose to get all the air out I can before I run it... The manual seems to say the air will self-bleed... Who knows! 6 of 1 half a dozen of the other!
Remember to have your heater on with the fan blasting when you do this also.
Mine always had crud get stuck in the heater hoses and heater core so I had to flush through the long heater hose and let it run out the short heater hose as well. I'm sure you've read this in other posts. The sensor and stat should still be on your short list as well though.
Mike

 

thanks for all the suggestions. i have not read any previous post. i am new to the jeep world and this forum. it as not happened in the last couple days. but i will still try all the suggestions. thanks agian