I thought I would post this up here in case it helps someone else out. Sorry in advance if it gets a little long. I had been fighting an overheating problem in my 2000 XJ for about a year and a half. It would get hot on long climbs or if I turned on the A/C.

1st Try

I started out replacing obvious things, Leaky Radiator, Water Pump, Thermostat, Cooling System Flush. I replaced them with cheap units from Pep Boys. None of these helped and I nursed it around for about a year like this.

2nd Try

I installed hood vents, ZJ fan clutch and swapped in a rebuilt engine (Cracked 0331 head). I was still having problems with getting hot, especially if I used the A/C or if I was on it hard. I even tried pulling off my front bumper, winch, led's with no difference. I then parked it in the garage for the winter and decided to worry about it when things warmed back up.

3rd times the charm

Finally about a Month ago I decided to replace my Radiator and water pump for OEM units to see if they would help. I went with the HD MOPAR RADIATOR and this time I actually saw a significant drop in temps. The new radiator is still a single row but the row is much wider (almost double) than the Spectra that came out. I also swapped the ZJ fan clutch back to new OEM mostly to quiet things down and temps were still good. It would still get a little above 210 with the A/C on at Idle and with A/C on while under load but no where near what it used to be. I decided to wire a switch to my fan so I could turn the it on when I knew it could use some extra help. After I wired the switch I noticed something weird, my fan would come on when the engine was cold but not after the engine warmed up I thought maybe I had messed up the wiring or had a bad relay but they all checked out. So I replaced the electric fan and that finally did the trick. I don't know why but my stock fan would only come on while it was cold if I the engine warmed up it wouldn't come on anymore. Now it never goes above 210. I just got back from Moab where I was sitting idling on the trails waiting for others while blasting my A/C and still never over 210. I actually haven't even used the switch I installed for my fan either now that the fan is actually working the ecm turns it on plenty to keep things cool.

So long story short, stay away from cheap parts and check to make sure everything is working when cold and hot.

 

I've seen some recent youtube videos where folks actually cut open brand new aftermarket radiators to show just how bad they are getting. Really Bad. Poor design, terrible materials, corners cut at every possible opportunity, and lots of manufacturing defects. Even obvious stuff like comparing their weights to show just how much material is being -cut- from the cheapo versions to make them cheaper.

Its gotten to the point where I have to cross check every new part I want to buy against the forums to see what the real "go to" variants are. Just look at CPS sensors, there are like 20 providers on amazon ranging from $20 up to $120. And generally, the consensus is that -none- of them are recommended (another go with OEM if at all possible).

 

Spectra radiators are junk! I had one blow the tank off in less than a year.

 

Yeah I learned my lesson the hard way now I check forum's anytime I have to buy a part to see what the best option is, which I learned most of the time is OEM.

 

Thanks for the input. Also it sounds like you added an "Auxiliary" switch and didn't disable the (217*) switch. Neat idea that. Lot's talk of going manual, but that's a better idea.

I call BS on the above. The fan could run backwards(wires reversed), but is "fed" by it's relay.
I think something tricked you. The E-Fan is "down-stream" of it's relay. Something else was changed when you changed the fan.

 

I wired a relay between the ECU and the fan relay, it grounds out the fan relay to turn on the fan with the switch but still supply 12v to the ECU so The CEL doesn't come on, and the ECU can still control the fan whenever it sees fit. Also I tested the stock fan by grounding out the fan relay directly while cold and hot but it would only turn on while engine was cold, and by cold I mean off for a few hours. I have read that the fan has an internal thermostat so they won't come on when temps are too high and suspect that had something to do with why my stock fan wouldn't come on hot.

 

OP, throw a bone to future searchers of this thread and provide the OEM part number for both of these parts.

 

Radiator is Mopar 52080104AC and like I mentioned earlier there are two different OEM radiators available and this is the "Heavy Duty" version.
Water Pump is MOPAR V9900083

 

Awesome! Thanks.

 

Trivial...ECU is 87-90, then PCM. (electronic control unit/power-train control module. (OBD-I till 97, then OBD-II)

Being it's just mill amps I do believe the added relay is not needed. Just grounding the fan relay with your switch should be fine. I think....

As far as the fan, that still sounds suspicious. Yes, there are electric motors out there with thermal protection, a "breaker" that will open the circuit if it's too hot. Until now I've never heard of our E-fans having that....Sounds like you know what your are doing, and did a nice job, wish I had that fan here to autopsy!

If it has one, we might call it the "GD". GD's of various sorts are installed in lot's of stuff. Removing the GD is often a cure. Because of forum rules we might call it the "God Darnit" (darnit's do not impound water).

 

The number of rows has almost nothing to do with cooling ability. Some folks think that "more rows means more cooling!"

Not true. Other design factors count FAR more than the number of rows.


Dem's good advices.




Yep. Me too.

 

Unfortunately on 97 and up you get a P1491 code (Fan relay circuit) if you try to just ground it out , I got the code when I was testing my fan by grounding out the fan relay. Also I still have the fan and would love to take it apart but don't really know what I would be looking for but maybe I could post some pictures. It would be nice to have it as a spare.

 

But having a 3 rows comparable to 1 row is supposed to be more efficient if moving more than idle speed? I just dropped a 3 row all aluminum rad in, and she sits 200-hair below 210 on days like today. (92 degrees + urban city heat) I've noticed the jeep running cooler than normal and I took out the e-fan due to it being seized.

 

I would suggest replacing the efan.

 

OH! I had thought you were grounding it with your added relay. So it sounds you have the added relay "in parallel" with the original? (so ether can power the fan).

Once on a (dead), bread machine, I drilled out the rivets holding the motor together, and inside found a little "fuse" about the size of a grain of rice on a winding. Soldered a jumper and it works.

Also I've seen thermal breakers. A small flat rectangular "component". Less then 2 inches long, 1/2 inch wide and < 1/4" thick.