Okay so about maybe a month and a half ago maybe more now i replaced the cylinder head on my 01 jeep because it had the 0331 crack issue. I took my time and replaced everything with top quality parts. head was a clearwater aftermarket cast, new fel pro head bolts, head gasket, intake/exhaust gasket.
I also changed the t-stat with a 195 stant. However it seems ever since i did this ive been having an overheating issue where then engine will get up to running temp and than stabilize a hair below 210 for a little bit and than start to creep up slowly to the next line above 210. It seems if i put a heavy load on it after its warmed up such as highway driving, or sudden acceleration the temp climbs faster.

now last week i was driving home and it was on the next line above 210 and than in a split second the gauge spiked to the right w/ the check gauges light coming on. I turned it off immediately and pulled of the road to coolant pouring out of my overflow tank. waited for her to cool down than drove it to a family members house close by to really cool down over night so i could safely get it home.

So this past weekend i did a complete system overhaul. replacing upper and lower hoses, water pump, and radiator. i also put some cascade in the system when bringing it home from its overheating episode. i also flushed the system.
after words i highway tested it ( at night however when it was cool) and it was at a stable 210 the whole time. however yesterday on my way home from work it started to creep up on my again and today the same.

So basically im looking for any ideas what the hell could be wrong with this thing. as a side note when i had the head of the old heads passages had a slew of rust and garbage in them.

 

What about the fan clutch,auxilary fan,and fan shroud?

 

From past reading the fan clutch is one of the things to replace when doing an overhaul. I'll let some of the more experienced guys chime in bit but I'm betting that will be one of their suggestions.

And because I'm curious, what brand t-stat did you go with?

 

I dont think it can be the fan clutch as i wouldn't be overheating on the highway if that was the case would i? the aux does turn on once the temp starts going up. The fan shroud i broke the top of while doing the head, once i noticed the heat problem i supper glued it back on as a temporary fix and the issue still remained. however i broke it again swapping the radiator in.

 

I put a stant in when doing the head, and last week i installed another stant 195 just in case that was the issue.

 

" It seems if i put a heavy load on it after its warmed up such as highway driving, or sudden acceleration the temp climbs faster."

Signs of a failing fan clutch. They don't have to fail (and rarely do) all at once. If you don't know how old it is replace it. Need to get a shroud to.

https://www.rockauto.com/catalog/x,c...for%2BROCKAUTO

 

Went out and got a new fan clutch today, hopefully i'll find the time to put it on tomorrow. however i still dont see how that can cause me to overheat on the highway when theres already a ton of air moving through the rad

 

Have u verified the dash gauge reading with a infrared point-n-shoot temp gun pointed at the t-stat cover? If I'm reading/understanding correctly, u have an extra stat......out of curiosity, have u tested it in a pan of water on top of the stove using a cooking thermometer? I agree, shouldn't need any fans at hi-way speeds, unless u have one heck of a tailwind.

 

"It seems if i put a heavy load on it after its warmed up such as highway driving, or sudden acceleration the temp climbs faster."

When I first got my XJ the temp would climb to 210 or a bit more after start up and stay there. From what I searched that was normal for these engines. First time it showed a sign of starting to overheat was when going up a 3 mile stretch of mountian at 55-60mph. Half way up the red light came on. Wasn't long after that I swapped out dash clusters. Next time it did it was when I went up same stretch. The gauge climbed to the near side of the red and stayed there. Third time was when the wife was on the interstate doing 70+ with the XJ loaded down. At no time did it boil over but it was HOT. All this was within weeks of buying it from the original owner who said it never overheated on her. I checked the fan clutch by watching while it was running and having the wife turn the engine off. Fan just kept spinning with next to no resistance. Replaced it and the problem stopped.

 

I had overheat but not boiling over on my 94 4.0L. All original 114K miles. Replaced the waterpump, t-stat,radiator bc it was clogged somewhat, new rad cap. New heater hoses and upper/lower hoses.
Anyway after all that, still ran hot going down freeway. Found out clutch fans ran about $35-40 bucks. So, I said what the heck cant hurt at this point.

Violia! Now no more over heating. Runs just under the 210 mark with a/c running in 90 deg weather.

 

I've got to admit that it doesn't sound logical.

 

Sometimes I think the 4.0L when in the XJ seems to defy coolant temp logic. However, when using a digital temp gauge (displays in 1* increments) vs dash gauge, it's easy to see how something as simple as a slight headwind vs a tailwind effects coolant temp when driving the same hi-way speed but different directions.

 

Guess I'll just keep doing what works.

What's your take on trans cooler location. I need to make a decision on where to put my trans cooler. Before or after the rad and in front of the rad/mech fan or not? Read a thread on another site where some were saying that because of the small size of these XJ rads you want let as much air get to them as possible. Hence,keep as little blockage in front of them as possible.

 

We installed a B&M #70264 auxiliary cooler. Since it is 1.5" thick vs .75" thick, it has a smaller footprint than the .75" thick units, thus covering a smaller area of the a/c condenser and radiator. The B&M instructions say for max tranny cooling, mount the cooler in front of the a/c condenser, directly behind the grille, inline with and after the OE stock rad mounted cooler. This is what we came up with 4 years ago and all is still good today.

 

^ That's the reason I bought that model#. Haven't even unpacked it yet.

I'd say 4yrs in the hot Texas sun is good trial run.