overheating question?

for a couple of months now, my 91xj 4.0l (8in, 35's etc..) has been overheating. There are no apparent leaks with the coolant, and even when maintaining steady speeds on street (35mph) and highway (65mph), the temperature gauge rises into the red. I havent ever had any problems with this until recently, and I am wondering if this is a radiator problem, or what? my electric fans are running properly and am I am just curious to the possible reasons for this sudden overheating problem.

WHEN WAS THE LAST TIME YOU REPLACED THE RADIATOR? WHAT SHAP ARE THE FINS IN?i HAD THE SAME PROBLEM LAST YEAR WITH MY 89 LIMITED AND I CAME TO FIND IT THE FINS WERE CORRODING VERY BADLY AND HAD TO REPLACE THE RADIATOR, PROBLEM WAS SOLVED. ALSO CHECK YOUR T-STAT.

unfortunatly this can be a conmmon problem in some of the earlier model xjs a couple of inexpensive things to think about would be to (if you havent allready) to check and replace the thermostat, flush radiator and flush coolant. those are gonna be some of the problem and are allways a good place to start.

I had the cooling system flushed, and that hadnt helped. The radiator is stock, and there didnt seem to be anythign wrong with the fins... the old radiator is why I believe to be overheating problems...but I didnt know if there is more to it...

it could be time to replace that old radiator there could be some crap down in the middle of it slowing the flow. also rember to change out the thermostat as well its like a 6 dollar part so might as well.

thanks for the advise. I appreciate it

Is your coolant boiling? Or are you just going by the gauge?
If your not boiling....................
Check your actual temp of the coolant before you go spending any money.
(get a meat thermometer and check it that way or go to your local shop and have them check it with a lazer thermometer)
I "THOUGHT" my 91 was running hot and spent almost $300.00 on parts before I found out it was a bad gauge.

dont forget your water pump...

Agreed on the water pump. The last time that mine went out, the impeller was actually turning on the shaft. YOu could actually hold the snout and turn the impeller by hand. Now, that is what I call shot.

the coolant is boiling....nnot everytime I drive it though

My 90XJ was doing the same thing. I replaced it with a radiator from a 95 or 97. The old one just didn't seem up to the job. I haven't had an overheating problem since I put it in almost 2 years ago. And like others have mentioned, check and recheck everything.

chris

Don't forget the fan clutch. $45 part from pep boys and takes all of 30 minutes to install. If it's the stock one, it's 14 years old and most likely not spinning as efficiently, if at all, as it did when it was new. If you already flushed the rad, do the fan clutch first. Check the lower hose and make sure it is still stiff. The springs in them tend to corode and break and they don't push fluid in well. Just trying to give you cheaper and easier solutions before replacing everything.

Also, do a search, as there are hundreds of threads on overheating. Read them over, and jot down the 10 or so recommendations for curing overheating. Don't waste your money on a high flow water pump. Your blades on your current one might be corroded and just need a new oem replacement.