joshgabel

here's the skinny,
00 XJ, 4.0 120,000mi.

WHat it does:
217* at idle
235* at idle with A/C
206-220 Highway sustained @ 60mph
All temps taken at OBDII port via Torque app and Bluetooth adapter.
Idle temps confirmed with non contact infra red gun (idle temps) measured at thermostat housing.
outside ambient temperature 100* (Austin, Texas) 80% humidity. Coolant temps will drop about 5* at night (80* ambient) but never below 206*.
Oil pressure cant be monitored via OBDII so i use the factory gauge, 30psi @ idle, 45psi @ 3K rpm



what has been replaced so far.

Brand new Clear Water cylinder head (updated design).
head gaskets (re-gasketed entire engine)
New head bolts
New water pump - 2X's 1st time cheap then OEM
New 3 row radiator from Radiator barn
Multiple thermostats ranging from 180* - 200* standt and OEM and vatozone junk
New thermostat housing
multiple rad caps from standt and OEM and vato zone junk.
New stock fan clutch then upgraded to ZJ HD currently, Metal fan blades inspected.
New fan shroud
New electric fan OEM and confirmed operation.
New temp sensor
50/50 coolant mix with Prestone universal gold, added WaterWetter with no change
New rad hoses
New trans cooler. (trans no longer routed through engine radiator)
New belt correct tension.
FLushed block multiple times both with water and chemical (right before cylinder head replacement). also replaced freeze plugs. everything was nice and clean.
FLushed heater core with garden hose flows free and clean.
replaced heater hoses.



Unrelated but also replaced.
New A/C condenser and Compressor...ect
New coil pack and rest of the ignition components.

Any help would be appreciated. I know there are a million overheating cherokee threads but i have yet to find one after multiple hours of searching that involves something i haven't already done.

EZEARL

If everything you've replaced is working as it should it could be an internal engine friction problem super heating the coolant. I take it you had a SERIOUS overheating at one time?

Improper fuel/air mixture,timng,and spark can all add to engine heat but I don't know if it would be to the extent your getting.

eloysmanuel

I bought a 99 xj that was overheating, when everything was verified all it had was the wrong waterpump (clockwise and counterclockwise are available)

thakmfb

Just because something is new does not mean its working properly. Your temperatures do not seem that far out of the realm of normal. Also three row radiators have not been shown to produce drastic differences. Most stay with a good quality 2 row

joshgabel

I have never had it over 240*. I bought it with "a blown head gasket". after having the head checked out and re surfaced i was informed of the crack between cylinders 3/4 just like all the rest of the 0331 heads. thus the replacement and the cascade of parts in the last year.

A/F mixture has been verified, new 02 sensors and new cat and cat back exhaust, New CPS, and synchronizer when coil pack was replaced. base timing and timing advance all verified via OBDII scanner (snap on versus).

joshgabel

thank you i will look into this.

joshgabel

Very true statement.. this is why i replaced everything i could twice (as much as i could afford).

Winter time it is manageable but it has been my experience that if a truck has a 195* thermostat it should remain within 10* of that designed operating range. so aren't my posted temps way outside of designed operating ranges?

CherokeePride

THis may sound dumb but what about your various relay switches? have you changed any of those? That is usually the first thing I change on a vehicle because they only cost about $11-$15 and can really help. My old 96 cherokee had an over heating problem that traced back to the relays. Thus the switch with each "new-to-me" purchase. cheap and easy and it doesn't hurt anything to change them.

jmrec100

Good Point on relays. Check the contact block too. Bad, corroded or just lousy connections cause the fan to work intermittent. Big problem I had on my old chevy until someone mentioned to check the fuse block connections.

joshgabel

replaced relays tonight... confirmed that electric fan is functioning properly.
Tomorrow i am going to install one 12" electric pusher fan on the passanger side and tie the relay into the factory fan signal wire and report back with test results.

Radi

I'm agreeing with thakmfb in not seeing a huge problem. You're on the warm side but not what I'd consider seriously overheating. 210-220 isn't abnormal and 230 with the AC running at idle in Texas heat doesn't surprise me.
100* air just doesn't cool that well and it's substantially hotter than 100* with the A/C condenser dumping heat into the incoming air.

The devil's in the details- I can tell you from personal experience that a cheaper three-row radiator is usually less efficient than a good 2-row or even a large tube single row aluminum, especially if the fins-per-inch count is marginal and the rows aren't staggered. In some 3-rows the rearmost row is obstructed by those in front of it but it carries 1/3 of the coolant. Not good.
I don't know what Radiator barn sells for a 3- row. Was there a manufacturer's name provided? What's the fins per inch count?

Not true that operating temps stay within 10* of the thermostat rating. The thermostat only sets the minimum operating temp. Maximum temp is set by the capacity of your cooling system. You'd eventually run the exact same temps with no thermostat at all.

Since you have an IR thermometer, what's the temp at the top and bottom radiator hose, compared to that of the t'stat housing? How about temps at the front and rear of the head?

joshgabel

I am not sure of the fins per inch count but it is the CSF brass/copper version.

I understand that the thermostat one dictates the minimum operating temperature. I was just mentioning that all my other previous vehicles (ford, chevy, dodge and toyota trucks) always maintained a very consistent temperature close of the rating of the thermostat.

I will shoot the points you suggest with IR tomorrow after work and post results. Thank you for your suggestions/help and interest.

joshgabel

I am not sure of the fins per inch count but it is the CSF brass/copper version.

I understand that the thermostat only dictates the minimum operating temperature. I was just mentioning that all my other previous vehicles (ford, chevy, dodge and toyota trucks) always maintained a very consistent temperature close of the rating of the thermostat.

I will shoot the points you suggest with IR tomorrow after work and post results. Thank you for your suggestions/help and interest.

Radi

CSF should be OK, at least equivalent of OEM if not better. That likely isn't your issue then. I was hoping they didn't sell you a no-name POS with bad engineering.

You'll run close to the thermostat rating if the vehicle has a lot of spare cooling capacity. Full size trucks often do, the XJ doesn't. The radiator's too small, too cramped behind it, not enough fan... Some guys vent or lift the hood to give that hot air somewhere to escape.
Mine normally runs 200-210 in the summer, if we get a 90 degree day I can add 10* to that. I'm curious what your radiator inlet and outlet temps are, and the head temps.

Cherockee

Just to be sure I would try another temp sensor. You mention that it's new, is it the only one you've been using since doing the work and having this problem? It's not unlikely that it might be giving the wrong reading.
Also, have you confirmed oil pressure with a mechanical gauge? With a previous cracked head and a previous owner not aware of what to look for there is still a possibility of damage to the block.
One more thing to check is the wiring to the temp sensor. Inspect the harness that runs along the top of the head. I have seen numerous '00-'01 Cherokees where the harness has gotten so hot that the wire insulation as begun to melt together. It's worth a look.