Fan clutches gradually loose performance the day they are installed. If unsure how old it is or if it's over 4-5 years, good time to replace it......it's the main fan and only +/-$35.

 

Thats a real helpful diagram.

I'm with ya on the likelihood that a Tstat change to a lower temp wont likely help. Matter a fact, these comp controlled newer models were designed to run at specific temps and if you lower that it can cause issues.

My XJ has 130k on it. Probably some scale build up in the rad. It seems to get hotter when running at higher speeds on the highway which is usually indicative of a inefficient radiator.

According to your diagram, I'm getting to the 222 mark when running steady 70mph with AC running. I'm not panicking but just wondering. No boil overs yet. Got good hoses, coolant and holding pressure well. She's loaded down with tools and ladders too so that add to the load on the engine, especially at higher speeds.

Pic in next post.

 

workin her good

 

I think I figured out my overheating (highway only) problem. Gunked up radiator. I had recently replaced my heater core so I cut it open to invesigate what buildup might be inside it. I figure if the old heater core looks like this, the rad is probably about the same.

Do I;

1. Buy a new rad? (are there heavy duty ones available or did the factory have lighter and heavy duty models?)

2. Remove the rad and have it professionally cleaned then reinstall?

3. Try a DIY flush kit?


Here's what the heater core innards look like.

 

My current rad is a 1 row aluminum with plastic tanks. I'm thinkin bout upgrading to 2 row all brass and copper construction.

What do you think?

http://www.rockauto.com/catalog/moreinfo.php?pk=338698

 

Copper/brass rads are old school. All the auto mfgs have gone to one row (very wide tube) aluminum core/plastic tanks due to their high efficiency to shed heat. +/-$100 will get u a new OE stock type rad.

U can almost bet your rad looks like the heater core.

 

I did some research and agree that aluminum is better as it disapates heat better. My stock rad is a single row aluminum. I just ordered a new 2 row aluminum unit. This is a work vehicle and it need to be reliable under harsh conditions. Upping to the two row is well worth the extra $ to me.

It was $237 all shipping included for the 2 row AL.

 

what research did you do. copper conducts/dissipates heat better than aluminum. manuf use alum VS copper because its cheaper 3 times cheaper to be rough.

aluminum 250 W/m•K
copper 401 W/m•K

source

 

Ok, I mis-spoke in stating that copper disapates heat better than aluminum.

My research was another forum discussion on the overall efficiency of older design copper/brass radiators vs newer design aluminum ones. I meant to say just that. The newer design AL radiators are more efficiently designed. Many times it has to do not only with the number of rows, but also how condesed the cooling fins between the rows are. More zig-zag fins per inch, the more cooling capability.

After shopping for a while for two row radiators, I had a choice of copper/brass for $285 or aluminum for $237. The 2 row aluminum has to be at least 50% better than a factory 1 row. Anything has to be better than my current plugged one.

BTW, thanks for correcting me.

 

Where did u find a 2 row aluminum rad? Gotta link?

 

rockauto.com

my stocker was a 3 row after all this talk of these garbage 1 row things i wish i would have taken a bunch of photos lol

 

6th one down on this list at Rock Auto $266

http://www.rockauto.com/dbphp/x,carc..._Radiator.html



I searched the same part number at Amazon and found it for $237

 

Check out the 2 row AL unit for the RH drive Cherokee at the Rock Auto link. Its only $168. The picture shows what looks like a second set of trans cooler or maybe oil cooler lines on one of the tanks.

Would the RH drive rad fit a LH drive Cherokee? If so, you can get a 2 row AL for $168.

 

Guess I missed where it said LHD 2 row aluminum. One thing to consider, those 2 row rads are only 1/4" thicker core than the stock 1 row.....they're not 2X as thick. They have 2 narrow tube rows vs 1 very wide tube row. The wider the tube, the more efficient.

 

no its not more thin tubes are more efficient because there is more surface area to dissipate the heat.