New radiator, new thermostat (installed exactly 1 year ago...) But it was 96 degrees out and I drove for like 25 mins, then when I got home... My overflow was spitting boiling antifreeze everywhere!
The thermostat and radiator was installed by dealer. What can be the issue... My friend who has an xj says his does that when he drives with the AC on, but what's the point of even having it if when u use it it overheats... Btw my temp gauge was 1 line past 210

 

Bad fan clutch, efan, water pump, rad cap. Fan shroud missing?

 

I'd lean towards water pump. What's your temp guage reading?

 

Yeah there are still a few components that you did not replace, as djb listed.

 

Fan works, shroud there, cap is good, hose is a little bulging but ok.
Not sure if it's related but also sometimes when first starting up and driving there's a high pitched noise that occurs only when I press on the gass...

 

The temp is 1 line past 210

 

which fan? if mechanical how do you know the fan clutch is good? how do you know the cap is good? bulging hoses indicate swollen/worn hoses or excess pressure.

you could also have head gasket issues, air in the system, or low coolant in general.

The noise could be your serpentine belt, which its unlikely but could be allowing the mechanical fan to slip on the belt when its engages reducing the speed of the fan causing it to be less affective... tighten it up, if its not cracked/worn. if it is replace it.

 

Yep, how can u tell if stuff works just by its looks/guessing? What looked bad about the rad and t-stat?......but they got replaced. You're still overheating, so replace the other 1/2 of the cooling system. That bulging hose sounds like the cooling system has been neglected for a while.

One line past 210 is 222+ on a '99. That's a little toasty.

 

Sound like you either have a blockage or no flow. You need to get on that, if not your gonna cause some engine damage

 

Are you running at least 50/50 coolant/water? Are you SURE the cap is good?
Water boils at 212 degrees....just a hair above the 210 mark on your gauge. If your coolant is boiling just above 210, your cap isn't holding pressure and/or you have a large percentage of water in there.

 

The previous owner used no antifreeze... For like 10 years... Now it's mine, i have a bit of a rust problem, but last year the entire system was supercleaned with chemical flush's. It was drained and flushed and backflushed over 5 times. It's now again a little rust covered, the radiator was replaced last august

 

It was fine for 369 days... I trust the work that the jeep dealer has done, but there's a new issue, weather more corrosion has broken free and is restricting a little flow, maybe... It stays cool while driving... Just not idleing... Especially in 90 degree plus heat

 

Getting warm at idle is usually an air flow problem. Check or have checked the fan clutch.

 

I would agree, either air flow issue or a coolant flow issue threw the radiator.

(not questioning if they did the work, or did it right. Even new parts straight from the box can be bad or have a short life. assuming can waste a lot of your time and money is all I was getting at)

I would change the fluid again if you can see rust buildup in the coolant again. the passages in teh radiator are VERY small and clog pretty easily with debris in the system. I would also replace the radiator cap (3$ part) as without the correct pressure it wont raise the boiling point to the correct temperature.

 

I had the same problem, I replaced my radiator and evrything worked fine for about a year. Then I had a problem with the coolant boiling out of the overflow, It would be fine while driving but as soon as I would stop or idle for a little bit it would boil out. I replaced the fan clutch, t-stat, cap, water pump & tep sending unit and still had the problem. Turns out that the bottom seal on my cap wasn't sealing against the radiator, the coolant was bypassing the cap and going straight into the overflow. I cut a thin piece of gasket material and put it in the neck of the fill tube and havent had a problem since.