Jeep overheats when idle

[CalPolyJeep88]

I have a 2001 jeep wrangler sport. It runs great except for when I idle for more then 30 seconds the temp gauge jumps to 260+ degrees. I just replaced my coolant last month and oil is new as well. Any ideas as to what is going on?

 

[tjlboise]

Try changing you thermostat. Starting out as simple as possible is the best way to go. Its sounds to me, like when you're moving, its being air cooled, but as soon as you stop, there's nothing going on to cool it down. So anyway, id start there. If that's not the problem, id move on to the fan(if its electrical), if not, then the water pump. Im pretty sure its gotta be one of those three things, but maybe someone else will have more suggestions. Good luck. I hope you get it figured out.

 

[82CJ7JEEP]

Could also be water jackets if too much rust/sludge is built up. X2 on fan or water pump. Doubt it is thermostat, would overheat constantly.

 

[tjlboise]

Could also be water jackets if too much rust/sludge is built up. X2 on fan or water pump. Doubt it is thermostat, would overheat constantly.

True, but you never know. Its worth the 6 to 10 bucks to find out. Being a 2001, and in cali, im not too sure how much rust there would be. Either way. Let us know how it goes.

 

[Smizar]

Have you checked your radiator fins to make sure they aren't plugged? Also pop your rad cap while it's running and see if you have good circulation.

 

[CalPolyJeep88]

Alright I'll try out those. Maybe start with build upon radiator and make sure circulation is good then move on to thermostat and fan then w/e is needed. Thx for speedy replies!

 

[elevatorman]

Does that thing have a fan clutch? What is the temp while driving?does it cool down if you raise RPM while sitting still?
Cooling at speeds says air is flowing thru radiator and water is also flowing which would rule out colapsing hoses etc..
Check flow in radiator at idle,and at higher RPM.Try changing and or remove thermostat for flow check,check belt tension,
if electric fan is it turning on and at what temp?

 

[jfrabat]

If it runs cool when at highway speeds, my guess would be the fan clutch. For a fix, I would do a Ford electric fan. Cost me all of $28 bucks, plus the switch and relay. The nice thing is that you can even shut your fan down for water fording... And the shrowd fits 2 of the 3 holes perfectly.

 

[Jester32]

Make sure the rad isn't plugged with mud or tree fuzz.

 

[sweetpeet]

These guys have mostly have it. But just to reiterate try replacing the thermostat and check the fan. I'd also say, go by advanced auto or a place like that and buy a coolant additive that makes it super cool. I've seen those around, never actually used it but hear they work. Also maybe an additive to get rid of any build up there might be. I have used this in the past, don't remember what brand but I do remember that it improved my temp about 80-90 degrees.

Also drop by napa and ask them for recommendations they can be very helpful.

 

[JPNinPA]

I agree with some of the above and have another to consider.
1.) Did you burp out all the air? If air gets trapped water will not pass while at idle but with more force from the pump at high rpm the water will push past the air.
2.) Clutch fans go bad.

Doubt it is the thermo or a clogged rad. It would overheat at high rpm becasue of the loss of cooling.

 

[jfrabat]

Doubt it is the thermo or a clogged rad. It would overheat at high rpm becasue of the loss of cooling.

That's the same thought process I used; those thing would make it overheat regardless of speed...

I'd also say, go by advanced auto or a place like that and buy a coolant additive that makes it super cool. I've seen those around, never actually used it but hear they work.

I would not get those super coolants; I think that would be a bandaid, and would not fix the real problem. If you want to get it after you fix the problem, that's fine, but you got a problem that needs to be resolved, not hidden... Otherwise, it could resurface while wheeling (rigs tend to run hotter when wheeling), and you could end up stuck in the middle of nowhere!

 

[CalPolyJeep88]

Alright thanks. I had heard that it may be an air bubble keeping the coolant from flowing when it idles. I just wanted to check on here to make sure that there wasn't something else that it could be that would be more serious. Going to work on it later today hopefully, Ill let ya know what I find.

 

[tjlboise]

How did this turn out?

 

[CalPolyJeep88]

Well I let it idle with the radiator cap off for a bit re topped it off and the let it sit and it didn't overheat but I am gna keep watching it too see if it can be anything else.

 

[tp=n=yj]

sounds like air . have some one step one gas alittle and add coolant and put the cap back on . also make shur your heater is on to get that air out as well.

 

[CalPolyJeep88]

Alright

 

[Rafaelr116]

That's the same thought process I used; those thing would make it overheat regardless of speed...



I would not get those super coolants; I think that would be a bandaid, and would not fix the real problem. If you want to get it after you fix the problem, that's fine, but you got a problem that needs to be resolved, not hidden... Otherwise, it could resurface while wheeling (rigs tend to run hotter when wheeling), and you could end up stuck in the middle of nowhere!

Was just reading this forum and I have a 1991 jeep wrangler yj with the same symptoms so I will try everything that was mentioned. Just seems to overheat when idling quickly especially in these hot Georgia days.

 

[JPNinPA]

Ask any questions you need.
At or above 35 mph there should be enough air flowing through the radiator to cool without relying on the clutch fan.
Below 35 you need the clutch fan to draw air through.

Be sure there is no dirt in the fins. On the outside.
Also be sure your fan belt to tight and spinning the fan. If the belt is shared with the air conditioner be sure the conditioner pulley spins free.