swedepowr1

I have spent several days reading most posts relating to an overheating 2000 XJ 4x4, automatic with 4.5" lift, 35's, and stock gears. I've been fighting a 2000 model with creeping overheating problem, whether in stop & go traffic, or highway speeds. I've done the following:

195* superstant
waterpump
fan clutch
new 0331 cylinder head with felpro gaskets (cyl 2/3 misfire & cracked head)
spectra radiator
rad hoses & made own lower rad hose spring
double flush (Peak) adding 50/50 antifreeze
heater hoses (Gates)
heater core (was smoking through vents & no heat)
removed exhaust manifolds & checked what looked like clear cats

XJ started off with overheating issues when i bought it, so i replaced the usual suspected parts . Cylinder 2/3 misfire and coolant leak under valve cover, bubbling in antifreeze reservoir prompted cylinder head replacement. XJ runs fairly well, but as temps creep up to 220/230*, engine seems to run rougher without any codes on my reader. electric fan comes on with a/c and temps over 220*. i'm at a loss as to where to go now. i'm trying to bring this XJ back from the dead, but its fighting me all the way. options offered up are hood vents, ZJ fan clutch, electric fan setup, but trying not to mask problems.

any ideas?

CR-Snow

Hoping you went with the TUPY stamped 0331 when you replaced it. I hate even ask this, but have you looked under the oil cap recently to check for cracked head symptoms?

Let's assume the head is good (fingers crossed)

Has the jeep been consistently overheating since a this work? Like had there been any amount of time that it ran well? If so what we were the circumstances around that time.

It looks like you've replaced a ton of parts. Could there be an air pocket? Did you burp the system properly when you flushed and filled after all those drains?

swedepowr1

new upgraded head bought from Odessa and installed

engine burped by slow fill, squeezing top radiator hose, temp sender on thermo housing loosened to evacuate any air

XJ has always had overheat problem; much better now but still creeping

swedepowr1

oh, yeah. fan shroud in tact and new tight belt with no slip installed. condenser and rad fins clear.

CR-Snow

Are there any conditions where it doesn't overheat? Or when it particularly does? Does it overheat on the highway, no AC? Just trying to get an idea of how it acts. What type of climate are you in?

CR-Snow

Just saw where you said it's hot in stop and go or highway. My bad.

Only thing I see on the list that could be overlooked is radiator cap? I've known several vehicles to run hot, only to have a faulty rad cap.

The running rough as it creeps up higher could possibly be due to hear soak. The fuel injectors, usually number 3, will sometimes get too hot to function properly on the 00-01's. But this is usually seen on a hot start. Like shut it off hot, wait a minute, start up hot and get misfires or poor idle.

swedepowr1

temps rise quicker than most of my XJ's. overheats on highway and stop & go. temps rise much slower with a/c on, but electric fan running; still creeps past 220* after awhile. charleston, SC. hot & humid, 90's and >80% humidity.

swedepowr1

heat soak a possibility for rough running. 3rd injector outer shell cracked but no leaks. no insulation or aluminum foil like stock.

CR-Snow

Still doesn't explain the overheating obv. If your cap is working then I'm not sure where to go next. I've put thermostats in from autozone before that were total junk.

swedepowr1

thx for great questions. ill test cap & pressure test system at same time. ive resurrected a bunch of XJ's, but this one has me stumped. engine did have a lot of rust originally, but block passages were cleaned. thx again.

toasterknight

I would verify the mechanical fan is working. If it isn't I would replace it with a factory replacement.

Firestorm500

He's already done the clutch.

I would recommend replacing the thermostat again, but this time with a factory MOPAR still at 195*.

toasterknight

Woops missed that both times I went over it.

Muddz

Not sure of the engine mileage. Did you clean out the engine block water jackets and replace the covers, thoroughly flushing only the engine block? If your not loosing any coolant and pressure is good. I would suspect blocked passages somewhere, would likely be part of the cause of a cracked head.

If the cooling system is ok, (no blocked passages), something is causing the engine to run hotter than normal. A good cooling system won't work as efficiently, with higher than normal engine temperatures.

My cooling system once had an overheating problem while climbing steep hills off-road in hotter weather all of sudden engine temps started jumping well over 230+ deg. F into the RED. Turned out to be the aux. fan was weak, fan seemed to work ok, just wasn't putting out enough CFM when turned ON ~218 deg. F. / OFF ~209 deg. F. After replacing aux fan the engine ran normal temps under the same conditions.

Year 2000\2001 should be > ~223 deg. F ON / ~217 deg. F OFF.

2000 A/C is different from 99 and earlier. When A/C is ON, besides the CTS the aux fan is also controlled by an A/C pressure switch that turns on or off the aux fan depending on A/C PSI pressure, regardless of the compressor being off or on. Previous years, A/C control is through compressor clutch engagement, compressor being on or off.

You might also want to consider installing a manual aux. fan switch. Manually turning on the aux. fan before the PCM setpoint , helps to prevent the cooling system and engine from reaching higher temperatures, where the cooling system becomes less efficient.

For off-road conditions and possibly high heat & stop/go traffic, I would install a HD radiator and a transmission cooler, a good transmission cooler will only drop coolant temps around 1 - 2 degrees, but help prolong the life of the transmission. OEM HD radiators normally came with off-road and towing packages.

swedepowr1

thx for all the ideas. im trying to keep it simple, reliable, and stockish. ill do the hd rad, thermostat, and rad cap for now. as a last resort, ive got several sets of Lumina Z34 hood vents, and 97-98 grand cherokee 4.0 regular duty fan clutch.