Electric fan issue, need some insite

Alright so i have a '99 xj 4.0l auto that i bought a few months back as a DD so far its been a great car (this is my first jeep) i owned a dodge dakota before this, but i was in the woods on a trail ride with some buddies of mine and it started to over heat 220* 225* so i raised the idle and turned the heat up and it cooled down enough to get it back on the road. Since then i got a new electric fan as a birthday gift replaced the old one to find out that wasnt the problem, today i replaced the temp sensor thinking maybe that was it and let it idle with the AC on and still no fan, i checked the fan relay and it all tested fine (jump pack and alligator clips to each tab on the relay till it clicked). what could it be? if anyone has some insight on what i may have missed it would be greatly appreciated.

Overheating at idle, or on the 4x4 trails, usually means the mechanical fan clutch is weak.

Have you serviced the cooling sytem ?

The cooling system is a group of related parts that depend on proper function from each of its component parts to keep the engine cool. Service the cooling system and replace any under-performing or suspected weak parts. Any component part of the cooling system that is not fully doing its job will stress the others and your cooling system will overheat. The most important maintenance item is to flush and refill the coolant periodically. Anti-freeze has a number of additives that are designed to prevent corrosion in the cooling system, but they have a limited life span. The corrosion causes scale that eventually builds up and begins to clog the thin flat tubes in the radiator and heater core, causing the engine to eventually overheat. Coolant should be replaced every 36,000 miles or every three years.


-Use a flushing/cleaning solution and then drain and fill the radiator with a fresh 50/50 coolant and water mix. With a neglected cooling system you may have to flush several times.
-Inspect the radiator for mud/bugs/grass clogging the outside and mineral deposits clogging the inside. Clean or replace as needed.
-Replace the thermostat with a STANT or Robertshaw 195* thermostat. Cheap thermostats are cheap for a reason.
-Replace the radiator cap if your Jeep has one. An old worn out cap will allow boil overs and/or allow the coolant flash over into to steam. You will see the coolant temps suddenly jump from 210* to the Red Zone and back to 210* if your radiator cap is weak.
-Inspect/test or replace the mechanical fan clutch. A worn fan clutch will allow temperature creep at stoplights, in heavy traffic, and on the 4x4 trails. A fan clutch that “looks” OK is not the same as working OK. Consider installing a Heavy Duty fan clutch such as the NAPA #272310.
-Inspect the electric cooling fan and the fan relay. Apply 12 volts and make sure the fan runs. Exchange the cooling fan relay with one of the others similar relays. Confirm that the e-fan starts when engine temps reach 215-218*. Repair or replace the fan or relay as needed.
-Inspect/test or replace the coolant temperature sensor that activates the e-fan.
-Replace the water pump. The pumping fins can deteriorate over time and the pump will not flow enough coolant to keep the temps under control.
-Inspect/replace the radiator hoses. Make sure the coiled wire is installed in the lower hose.

If you have covered all the points listed above and still have overheating issues, inspect the head for cracks and head gasket for leaks. Exhaust gasses entering the coolant can raise the temperature of the coolant or cause steam pockets in the coolant that will temporarily block the flow of coolant

Read more about cooling systems here –

www.offroaders.com/tech/engine-overheating.htm

www.familycar.com/classroom/coolingsystem.htm

Thank you Tim_MN
As soon as i get a chance i will check into all the above.
When i bought the jeep i flushed all the fluids oil, coolant, tranny, and i had to replace the radiator cap all of the fluids and cap and temp sensor are less than two months old.
Also i tried switching the relays under the hood and nothing happened again i turned on the ac to see if the E fan would come on but no luck.
Sitting in traffic it stays at 210* no problem and temp stays there on the highway and in town in stop and go traffic. The only has a problem on the trails it gets hot while sitting (waiting for others or when someone gets stuck)
So my best guess is the fan clutch is working, I just wanted to see what else i could do to get the E fan working before wiring it to a switch.

As for corrosion there is a bit where the temp sensor is where the two coolant lines go into the engine my guess is a worn gasket which i will be replacing soon. Thank you again for the insight, as soon as i check everything i will post with results.

Note from DJ

Woodtket you ststed “I turned on the ac to see if the E fan would come on but no luck”.

Did the A/C compressor clutch pull in?

Old water pump, clogged radiator, or bad Tstat? All three suspect and work the system asTimMN mentioned above but the first three are classical failures on that vintage with 13 years.
It is a marginal cooling system without lots of airflow.
Electric fan only comes on if there is a demand for A/C (Freon pressures also consent the switches to engage the compressor clutch) or temp over about 218 F. My '98 with original radiator just a year ago would get to the electric fan cut-in temp (just over 215 F or so on the gauge) when in slow traffic....and the electric fan was enough to bring the temp back down to below the cutoff point in about 2 or 3 minutes. Sounds like your pump isn't pumping enough or you have internal or external flow issues with the radiator.

So should i undo the lower radiator hose and put a pressure tester on it to see if it will flush out any gunk after i use a coolant flush? or replace the radiator?,
I drive over 100 miles a day commuting to both jobs so i rely on it and often sit in traffic so before summer hits i'd love to have everything in pristine working order. I'm not sure how to post pics but i have one of the front of the engine where it seems to be leaking coolant.

Here is the thing. The Aux Fan should not have to come on if the cooling system is in proper nick. It is there to provide the extra cooling required when the condenser is dumping heat in front of the radiator and as a safety in the case where the Heep is running over-temperature.

So, there are two issues here and the first thing to do is get the cooling system properly sorted.

As to the fan, do you have a meter? Either a simple Volt Meter or a Digital Multimeter will work. With the ignition on, there needs to be battery voltage at the connector to the fan. As is the case with all of the active devices on the Heep, it is controlled by providing the ground connection by the PCM. In this case, there is a relay involved. There should be, if I remember right a Black wire and a Light Green with a White Tracer wire in the connector at the fan.

If you have battery voltage at the fan, then the relay could be at fault. Just because it clicks, does not mean the contacts are good... Or, the fan itself could be at fault.

So, you can "hot wire" the fan directly to the battery to eliminate the fan. Disconnect the fan from the harness via the connector and run wires directly to the battery. If the fan fails to start, here is a proceedure to attempt to save the fan. I have used this on more than a bunch of fans over the years... And, for that matter on vehicles other than Heeps. It is a universal problem.

Over time, carbon builds up in the motor causing several problems. Sometimes the electric fan starts running erratically, like it does not always want to start. Sometimes, when you turn them by hand, you will feel them "cog". By this I mean that it feels like it is going past notches. A DC motor should turn smoothly.

Here is how to reclaim a 97+ Fan Motor.
1. Remove the C-Clip and metal spacer securing the blade to the motor.
2. Remove the blade from the shaft. Tap the motor shaft LIGHTLY to get it off. DO NOT PRY ON THE BLADES, THEY WILL SHATTER!!!!!!
3. Remove the three screw securing the motor to the shroud.
4. There are several tabs that are bent down holding the backing plate. Gently pry these up to release the backing plate. Be very careful as you will be re-using them!
5. Blow out the built up carbon dust from the inside of the motor. As the motor operates, the brushes wear, depositing carbon everywhere. This shorts the segments causing the "Cog" feel.
6. Gently clean between the commutator segments to remove the carbon. A very small scribe works well.
7. Reattach the backing plate by gently bending the tabs back into place.
8. Reattach motor to shroud.
9. Reattach blade.
10. Test.
This is a, usually, one time repair as the tabs holding the back plate on tend to snap off with repeated bendings as they are just thin sheet steel. It is also possible to just buy the motor by itself. Google the part number that is printed on the motor. It is a Bosch Part and can be had separately from the entire assembly.

o-gauge-steamer said:

With the ignition on, there needs to be battery voltage at the connector to the fan. As is the case with all of the active devices on the Heep, it is controlled by providing the ground connection by the PCM. In this case, there is a relay involved. There should be, if I remember right a Black wire and a Light Green with a White Tracer wire in the connector at the fan.

Click to expand...

The power wire to the fan is switched by the relay. The relay is actuated when the PCM grounds that circuit, but the fan runs on switched power. The wires are light blue for power, and black for ground. Picture in first post shows the factory schematic.

http://www.naxja.org/forum/showthread.php?t=1025399

Try this......

http://www.lunghd.com/Tech_Articles/Cooling/Electric_Fan_Diagnosis.htm

That info is for a Renix. Different setup than his 99.

hubs97xj said:

That info is for a Renix. Different setup than his 99.

Click to expand...

That'll teach me to skim articles.......:anon: