What is the condition of the fan clutch ?

 

Yes the head was resurfaced. As for coolant I’m running 50/50 which has always worked good for me.

 

Yes both were checked for cracks. And if you’re referring to air bubbles rather than exhaust bubbles I’ve tried burping the system a few times and can’t seem to get any air to come out.

 

Im under the assumption that if you can freely spin the fan while the vehicle is off then the clutch is fine. Is this correct or am I missing something? If I’m right then the clutch is perfectly fine.

 

https://www.wikihow.com/Test-a-Fan-Clutch
Turn the fan by hand. With the Jeep off. Grab the edge of one of the blades and give it a good push. While there should be a little bit of give, it shouldn’t spin more than three complete rotations. Too much free-wheeling is usually a sign that the clutch is prone to slipping. On the other hand, too much resistance means the clutch is binding and can’t turn freely. In either case, it will need to be replaced.

• Ideally, the fan shouldn’t spin more than 1-1½ times

 

Well the fan is definitely not spinning anywhere near free enough. I cannot get anywhere near 3 rotations let alone even half a rotation. So I think replacing that is a good place to start

 

No, your fan clutch sounds fine. If the fan can't be spun easily by hand, that means the clutch is working. As the clutch gets warm, it supposed to get stiff and connect the fan to the fan pulley so the engine will spin it. If you can spin it freely when the engine is warm, then the clutch has failed and it's just freewheeling instead of being driven by the engine.

 

The fan starts spinning right when the motor is started. Is this correct or should there be a warm up period before the clutch engages and starts spinning the fan?

 

General consensus around here is if you don't know the age of the clutch replace it. They don't just go bad all at once. It's a gradual process. So at what point it causes overheating who can say.

 

I can't say for sure that your fan clutch is gone but maybe you can relate to my personal experience on my XJ also a 99. I had coolant boiling out of the overflow, the previous owner took it to a mechanic who loved using the parts cannon. He changed the water pump, thermostat..... But still had issues. After I purchased the XJ I noticed this over boiling issue and he told me what has been done so far. So I tried spinning the fan clutch and it was real stiff even with a cold engine. And yes it looked liked it was spinning fine when the engine was on.
Being that I couldn't even get one normal rotaion when I spinned by hand I replaced it, this solved my issue, by the way the XJ only had only about 70,000 miles on it at the time. So they do wear out even at low mileage, plus it's an inexpensive part less than $25 shipped at amazon ( ) and mine was made here in the USA. The part is Hayden 2625

 

If you are confident the temperature was not much above 210, then the problem is probably not temperature related. So thermostats, fan clutches, and water pumps are not going help. The problem is more than likely pressure related. The coolant is boiling because the pressure is not being contained. It needs the pressure to keep from boiling. As previously mentioned, the first easiest place to look is the radiator cap. The second is the possibility that there is still a lot of air captured in the system. The third is that the system is not sealed (somewhere other than the cap). I can't recall if you mentioned if the coolant system has been pressure tested?

You might consider another Mopar radiator cap, to rule out that the old original one and the generic after market ones are not part of the problem. I don't like throwing parts, but they aren't very expensive, and you can always use a good Mopar spare.

 

The typical failure mode for the fan clutch is the oil has leaked out and it spins freely, and thus isn't running at full speed when the engine is warmed up. It's much more rare to have a fan clutch that is bound up and driving the fan full speed all the time.

 

Well I changed the fan clutch and the thermostat the other day and seem to be in good shape now. I have not logged a ton of miles or gone wheeling which is where it would get the hottest but it’s running good so far. Still getting a few air bubbles in the overflow tank but it is definitely not boiling like before so I’m satisfied so far.

 

I used two t-stats of same mfgr and temp(195) The first one kept temps right at gauge center (210) Then after a year I noticed the temp running high (230) and later blew a radiator when I pushed the car with the AC on. Replaced said radiator and this t=stat runs the engine low on the guage (190) until I push it with the AC on these hot days (98). NOW I see 210-215 as the hottest.

Engine is completely stock.

 

I had same issue. I had overfilled the coolant overflow tank to near the top. When car was hot the coolant rose high enough to come out the over flow tube. Once the hot coolant touched air, it would start to boil with the coolant in overflow tank boiling over. Over flow coolant would continue boiling out until all coolant came out of the tank.
Once the system cooled, I refilled to the refill line, purged air from the system, ran it up hot, let it cool back down and refilled to the refill line in tank.
This fixed the issue