Running hot in traffic, everything is NEW

Hi everyone. I've been chasing this issue all summer, which finally culminated in me replacing the entire cooling system last weekend only to have it still run hot in traffic. Jeep is a 1995 sport, 4.0/AW4/242.

The following is brand new:

CTS
2 row all metal CSF radiator
Stant super stat thermostat
OEM Mopar Water Pump
All hoses (OEM with spring in lower hose)
Electric Fan (Dorman)
Fan Clutch (Napa heavy duty ZJ)
Radiator Cap (twice)

Before I replaced all of this I ran a 6 hour chemical flush through the engine and then got all of that out.

I always come off the highway and sit in traffic going to work. I am seeing this:





So what did I do? I turned on the AC and THEN the e fan kicked on. Temp went right back to 210*. So it seems to me that the electric fan works, but just isn't kicking on when it is supposed to at about 220*. Any ideas? I've been searching the site for weeks but can't seem to figure this out. BTW, as soon as I pull the CTS plug the fan comes on and I get a check engine light, just as it is supposed to be.

i too noticed higher general coolant temps after replacing the oem radiator with a 2 row csf. might have something to do with the fin density which appeared greater on the oem rad. often times my temp will hover around 215-220 while sitting in traffic after running on the highway too, i dont worry about it too much unless it boils over and bumps the red though. if it bothers you try searching for the manual electric fan switch writeup or dual electric fan install threads.

QUABOAG said:

i too noticed higher general coolant temps after replacing the oem radiator with a 2 row csf. might have something to do with the fin density which appeared greater on the oem rad. often times my temp will hover around 215-220 while sitting in traffic after running on the highway too, i dont worry about it too much unless it boils over and bumps the red though. if it bothers you try searching for the manual electric fan switch writeup or dual electric fan install threads.

Click to expand...

Thanks. What do you figure that temperature is, 220? 225?

The last rad I had in this XJ was a CSF also, and it didn't seem to do this ever. Until this summer, that is.

I've also been anal about doing yearly coolant changes the last 5 years since I replaced all this junk the first time.

I'm definitely going to try and rig up a switch to the e fan, I have a feeling I'm not going to be wanting to hit the AC all the time this winter to keep it cool in traffic.

well i know on my jeep i have a ultra guage that gives me true numbers and not just a random needle sweep. And my electric fan doesnt turn on until it hits 223 then it will cool it down to 210 in a matter of a couple minutes.

the origional rad in my xj kept the temp at 195-200 or a click below the middle on the gauge. it started leaking along the tank seam last winter so in the spring i put in the csf2 row all metal rad. immediately i noticed it hardly ever ran below the 210 mark after the engine warmed up. in fact, cruising on the highway it hangs around 210, idles in traffic around 215-220 since i replaced the electric fan, bumped the red idling on hot days when the electric fan got lazy! all the parts of the cooling system in my junk have been replaced including the cts. i just chalk it up to the general size of the xj rad being small and lower fin denisty on the affordable csf rad. i doubt you will have any problems this winter with creeping temps unless you live in a place where it doesnt get cold!

OK so now if I do something like this:



It's going to shoot current into my PCM isn't it? The XJ is a 1995.

Use a 5 pin relay instead, with the stock power wire on the NC terminal, the new power wire on the NO terminal, and the wire from the fan itself on the common terminal. Switch on, fan runs constantly. Switch off, fan works like stock.

hubs97xj said:

Use a 5 pin relay instead, with the stock power wire on the NC terminal, the new power wire on the NO terminal, and the wire from the fan itself on the common terminal. Switch on, fan runs constantly. Switch off, fan works like stock.

Click to expand...

Gotcha. I think I can figure that out.

Drawing sucks, but this is how mine is wired. Got the idea from another member here.

http://s266.photobucket.com/albums/ii244/AHhub/forum stuff/FanPCMBypassed.jpg

hubs97xj said:

Drawing sucks, but this is how mine is wired. Got the idea from another member here.

http://s266.photobucket.com/albums/ii244/AHhub/forum%20stuff/FanPCMBypassed.jpg

Click to expand...

You can wire the relay as Hubs posted or another option is to put a jumper from the purple (87) and do away with the switched 12V yellow (86). Instead of putting a switched 12V to the actuation switch you counld switch the relays ground and attach the yellow to the ground on the relay (85) and do away with the ground wire going directly to ground.
Don't forget to fuse the wire you run from the battery according to the gauge wire you use.
This way you only run one hot lead and just switch the ground lead.
You dont have to use a light up switch; just switch it up for ON and down for OFF.

That is probably right at 220 degrees on the gauge. If you notice the lower half of the gauge is 100-210 degree span (110 difference) but the upper half is 210-260 degree span (50 difference), so the needle does not sweep at a consistent rate. Even if it were consistent for the upper half (which it isn't), the 3/4 hash mark would be 235 (260-210=50/2=25+210=235), while half of that (where the needle is in those pics) would be (235-210=25/2=12.5+210=222.5). Since the gauge sender and the ECM temperature sensor are different on your 95, you are basically in the margin of error there.

If it were me I would try to find a way to confirm the gauge. One way is to with an infrared gun pointed at the thermostat housing. You can also get somebody with a shop scanner to read the ECM temperature sensor and compare that to the gauge.

Also keep in mind that the stock gauge sender is in the back of the head while the ECM sensor is in the front at the thermostat housing. They are going to be different.

When my gauge says 210 my thermostat housing is 185. I have a 180 degree thermostat. When my gauge is at the next line on it my thermostat housing is 195. When I had a 195 degree thermostat it always ran at this line. I have had three gauge senders and they all read the same. Is it possible to replace the gauge without replacing the entire cluster?

I had problems with gauge sender until I switched to the cheapo autozone house brand. Standard senders were always wrong every time

My last sender (which I think was a Standard piece) was off by 30* out of the box. Verifying the actual temp, especially with new parts, is never a bad idea.

x2 on checking the temp with a thermometer gun. my xj is the same year as yours and i have the same problem. i had a gauge temp sensor from oreilley's and it was way off. switched to oem mopar piece and it reads much more accurately but the gauge still reads hotter than the temp itself.

Regarding the gauges themselves, I haven't dug into a 97-up version, but it's definitely possible to remove the individual gauges from the earlier types. Not all years are compatible even if they look the same, so swapping can be a problem, but it might be possible to recalibrate a gauge that's working but inaccurate. I did this with the voltmeter on my 95. The gauges are calibrated by the placement of a little magnet. It's stuck on with a dab of glue. Real high tech stuff here. Pop it off, reglue it, and voila, recalibrated.

Of course it's easier to check how inaccurate the gauge is and then just live with it, but it can be irritating.

I didn't have a overheating issue, I replaced the radiator due to a crack. I bought a 3-row CSF on recomendation. Now the AUX fan runs all the time and it runs hot. I compared the CSF unit to the stock HD unit and it's clear the fin density is much less on the CSF - about 1/2 as many fins per inch as the stock unit. Now flow is probably more inportant than fin density to transfer heat so it could be a combination of these factors. There is no air in my system. The CSF, although all metal and looks to be constructed well is of poor design. I called them and emailed them and no response what-so-ever. I'll never buy CSF again.