Aquired this vehicle last fall, didn't drive it much but it seemed to be running well/predictably. Began using it as a DD this late winter/spring. Running like a champ. Sometime after replacing e-fan, I recently noticed high-ish temps in stop/go after freeway driving. Fan engages correctly with A/C. Bought thermostat then noticed radiator leak. Replaced radiator, thermostat and deleted heater control valve while at it. Still hot in stop/go. Replaced temp sensor in thermostat housing. Still gets hot. E-fan seems not to be engaging at higher temps. ECU?

Thanks.

 

Not ECU. Probably water pump. Maybe fan clutch. Those buggers are just about impossible to test reliably. Not very expensive for both. Given the cost of overheating (trashed head or engine), it seems prudent to just replace both.

When they get looking like this, they don't move a lot of water.

 

Water pump is easy and inexpensive, I agree. I'll put one in next weekend, but I like to understand "why". How would you explain the e-fan not engaging at higher temps?

 

Ah! Sorry, El, I missed that. Slap me.

Test the fan itself first. Grab some wire and jump 12 right to the fan. Polarity won't matter - if you get it wrong it will just spin backwards. There is a plug not far from the fan. Wires run back along the driver's side inner fender. At the moment, I can't remember if you need to remove the airbox to get to that plug.

If the fan works, you ave a relay (in the PDC) and a temp sensor to consider. For the relay, just swap it with a known good relay to test. Borrow from one of the other circuits.

 

Fan works, man. Comes on with A/C. Tells me relay is good too? New temp sensor today. Also, if I unplug fan it stays on (default?) and "maint reqd" light illuminates. Still doesn't seem to engage at higher temps if left plugged in.

 

What are you calling higher temps? IIRC, it comes on at 217 or 218. These things run hot.

 

Good luck seeing the efan kick on when the engine gets hot. I think they fubared this part of the 96. Like you I changed temp sensor and relay, and still I can't get it to come on at 218 like the FSM says. Even at 230 it doesn't come one. I have only seen and heard it come on twice, because of high engine temp, in the 10 years I have had my Jeep; and both times the gauge was close to red lining - I was stuck in highway traffic, barely moving, 95 degree days with plenty of humidity. I have tested the efan, and it works when the AC is on. But other 96 owners also complain of this issue.

Just today I was testing the AC on the driveway and it was running in a 215-220 range. Fan clutch, efan, radiator and thermostat are all 3 years old. And I have flushed the cooling system twice. I have just resigned myself to believing the 96 runs warmer than normal.

If you do figure it out, please let us know.

 

Before the tstat change, the gauge resided just left of 210. I don't remember seeing it travel above that until a coupla weeks ago. It was nearly red lined, so I turned on the heat and the temp came down. Since the tstat change the temp gauge resides just to the right of 210. It now regularly climbs as high as the third mark on the gauge without engaging the e-fan. I can't remember it getting hot like that before, and although I checked the old e-fan's performance by seeing if it ran with the A/C, I can't recall specifically knowing it engaged due to high engine temps only.

 

A nice add on to the cooling system is a trans cooler, get the larger size option, I mounted mine in front of electric fan side, secured to rad frame, not rad, about 1" out from rad, I still run thru the rad then the auxilliary heater, perhaps some would reverse that or bypass the rad, any way you work it, a cooler trans provides less heat to the rad, and trans last longer.

 

I'm fairly certain adding a transmission oil cooler will have zero effect on when the electric cooling fan engages.

 

When I first got my '96 9yrs ago under certain conditions the coolant temp would get to the point where the e-fan came on. Problem was a weak(they aren't just either good or bad)mechanical fan clutch. Everything else on the cooling system had been well maintained(original owner is a personal friend). E-fan would kick on with A/C and at ~218. I recently replaced the entire cooling system except for the heater core. The OEM cooling system is entirely adequate when it operates at 110% efficiency. And the '96 XJ runs no hotter than any other yr XJ. Unless your doing a lot of towing or MAYBE low range crawling you won't need an auxiliary trans cooler.

As Mark eluded to maybe your not running as hot as you think. Don't rely on the gauge. An IR gun aimed at the t-stat housing will give you the true reading.

 

Sure, but it's definately running much hotter than it was, according to the gauge, which utilizes a sensor that hasn't been changed. That is my concern.

 

What brand t-stat? You haven't changed the gauge sensor in the back of the cylinder head?

 

Although the high temp condition began before I changed the thermostat, I beleive the recent replacement is a Gates. I put it in as a possible remedy for the high temp situation. As I mentioned above, the sensor near the firewall has not been changed, but it sends the signal to the gauge only, and has no effect on when the E-fan engages.

 

We recently went through this same scenario with another member. You've got to verify the temp with an IR gun. Although I had no over heating problems before I replaced my system my gauge now reads a bit differently than before. They just can't be trusted especially when they show extreme readings. It is my understanding that the e-fan kicks on when the coolant temp is ACTUALLY ~218 not by what the gauge shows.