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Topic Review (Newest First)
08-21-2011 01:27 PM
CJSteves It's frustrating, isn't it? In my wildest dreams I never thought I'd have the issues at high speeds, I figured crawling through a rock garden would be much harder on it, but I guess I was wrong. Even here in AZ I don't use the AC that much, but if I did I'd be more worried. If it's at where it's at now on the interstate, what would it do working harder with the AC on? I'm sure it'd be a bad experience...
08-21-2011 01:22 PM
mudslinger5000 i have this same problem. i have 33x12.50 tires and when i go down the highway it does the same thing, but regular roads the temp is normal. i actually drove it to the beach last year (7 hour drive) and when we got about three hours away the needle was in the red zone and i had to stop for about an hour and let it cool.
08-21-2011 01:22 PM
CJSteves Thanks, Jerry. I think I will see how this one does for a few months and if I continue to have concerns (or if performance degrades) I will go with a current OEM replacement.
08-21-2011 01:18 PM
Jerry Bransford
Originally Posted by CJSteves View Post
Thank you for the response! Just for information sake, the next time I replace the radiator is it worth it to go with an all aluminum model then? I went with all metal to avoid the separation issues between the reservoirs and the core. Also figured the three cores would provide more surface area for heat dissipation and make up for the differences between the specific heats of brass vs. aluminum.
The OE radiator already has an all aluminum core and all aluminum cools best.

Though this is counter-intuitive, more radiator rows does not necessarily mean better cooling. In fact, the factory went from a 2-row all aluminum core to a 1-row all aluminum core to achieve slightly better cooling efficiency back around 2002 or so.

Early TJ radiators did have a problem with the plastic top and bottom leaking from where they are attached/crimped to the core. My '97 TJ's radiator was unsuccessfully fixed/replaced three times before they gave up with the early leak-prone OE radiators they were getting at the time and instead installed an aftermarket radiator they purchased locally. However, the factory finally got that problem fixed and it's now rare for them to leak.

Personally, I'd go for the current OE replacement (like you can get cheaper from which works well, is very good quality, and has a 100% aluminum core instead of the junky Chinese radiators places like Radiators, automotive radiators, condenser, oem radiators, truck radiators is selling.
08-21-2011 01:13 PM
CJSteves Awesome, thanks for the info! I am not too concerned about it, but it makes me edgy. I am going to pursue regearing ASAP and see what effect it has. Hopefully it will help put the engine back in more of a "stock" situation. It just seemed strange to me that the temp would creep up higher at higher speeds, I figured with all that air flow and an (essentially) new cooling system, there should be no reason it doesn't perform excellently. It does stay below 210 under 99% of other driving conditions, though, whereas prior to the replacements it would hover right at 210, so it has had some effect.
08-21-2011 11:38 AM
doclouie I too went with an all metal radiator for the same reason, but mine is a two core. If the radiator does spring a leak in the back country I actually have the needed tools to solder it back up. If the plastic one splits though, I would be out of luck. The stock radiator has a 1 core aluminum. Here are some pictures from when I replaced mine.

More is not always better when it comes to radiators. The first row of fins in a 3 core radiator cool down the water the most and then it is goes down from there. Don't get me wrong it can help in some circumstances, but in the Jeeps it looks like it makes them run just a little bit hotter. Do not worry about going all aluminum as the cost to increase in performance really would not be worth it as the stock radiators do well. Also some aluminum radiators are actually epoxy lined which is awful for heat transfer. If your Jeep hits up in the red then you may have a concern, but I do not believe that is your problem. Just enjoy the ride even in the hot Arizona sun. I am just glad it does not get that hot in Utah.
08-21-2011 10:33 AM
CJSteves Thank you for the response! Just for information sake, the next time I replace the radiator is it worth it to go with an all aluminum model then? I went with all metal to avoid the separation issues between the reservoirs and the core. Also figured the three cores would provide more surface area for heat dissipation and make up for the differences between the specific heats of brass vs. aluminum.
08-20-2011 10:32 PM
doclouie Yea you are working the engine a little harder so it will run a bit hotter, but a hair over 210 is normal especially where you live. The 3 core all metal radiator also will not cool as well as the stock 1 core aluminum radiator. Heat transfer to aluminum is a lot better than it is to copper or brass. If it gets into the red you should worry, but a tad bit above 210 is pretty normal when it gets 100+ outside.
08-20-2011 10:25 PM
Any Relationship Between Gearing/Cooling?

Hello all! May I ask a bit of a silly question?

I have a 1999 Wrangler with the I6 4.0 L and a 5 speed. The previous owner put a 3" lift and 33" tires on it. i don't think they ever re-geared after changing tire size. I am planning on having a local shop set it up with 4.56's.

Question: what is the relationship between gearing and cooling load, if any? Here's the reason I ask... I have noticed that my Jeep tends to run a bit hot (in the Phoenix summer, so it's working hard) on a somewhat regular basis. For instance, today I was driving about 65-70 on the highway, in 5th gear, varying degrees of grade, no A/C on (top was off) and I noticed the temp gauge was a hair over 210, say maybe 215. Immediately upon getting to town and dropping back down to 40-50 miles per hour the temperature would drop to normal levels. Is this possibly because the mis-match in gearing causing the engine to work harder at high speeds on the interstate? Should I expect for the engine to be "happier" and back to it's prime operating zone after re-gearing? I've always understood re-gearing was basically getting the vehicle back to the operating conditions that it had when it left the factory, just with bigger tires now... Hopefully that is an accurate assessment.

Before anyone asks, the radiator was replaced less than 2 months ago with a brand new, 3 core all metal model. Thermostat was replaced with OEM, and waterpump was replaced with OEM model. Cooling system was flushed, and also replaced the fan cluthch with a "Heavy Duty" Hayden model. After all of this, I expected the old gal to be running cool all the time, but she still skirts above 210 more often than I would like. Granted, it is Arizona and it is summer.

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