Help, I'm absolutely confused!!

Ok, In the past 6 months Ive replaced my: Thermostat housing, thermostat, radiator, a/c condenser, and water pump.

Originally had a 160* thermo in my jeep, and I started getting overeating issues, immediately i thought it was the wrong thermo, of course.

So last weekend, replaced the thermostat with a factory 195* and did a deep flush of the block and the radiator.

Ran my jeep on the street for a total of about 4 hours in the last week, never peeked 210.

I start offroading last night, for a good 20 minutes, and all the sudden it just SPIKES HIGH!!!

Overheating like a mofo.... Relieve the pressure from the system, let her sit, and it cooled down to 210 again... run it for 2 minutes MAYBE just babying her, and im already kissing the red line again...

What can I do? Whats next? Whats left to replace?

Since you do not overheat when you have airflow through the radiator that leads me to think that there is either a problem with the mechanical fan and thermostatic clutch or the elecrtic fan and related circuits. Does the electric fan operate when the engine temp. is above normal? If not look at the Temp. switch or sensor (depending on year) the fan, relay and all the wiring.

Well, My XJ has A/c, but It doesnt work, so I never turn it on.

I was told that electric fan only comes on when the A/c is on... if this is true.. Why Cant I just wire that elec fan to a switch?

And can that electric fan REALLY do THAT MUCH?

Since you do not overheat when you have airflow through the radiator that leads me to think that there is either a problem with the mechanical fan and thermostatic clutch or the elecrtic fan and related circuits.

Click to expand...

I was thinking something along that line. If the only difference in those two instances was air being pushed through the radiator, it would make me think the fans arent doing their job. Is there a way to run the fans to a switch so he can manualy keep them on while sitting still to test it out?

Speed_racer said:

Well, My XJ has A/c, but It doesnt work, so I never turn it on.

I was told that electric fan only comes on when the A/c is on... if this is true.. Why Cant I just wire that elec fan to a switch?

And can that electric fan REALLY do THAT MUCH?

Click to expand...

I think it should come on with temperature also, but there's certainly no reason you can't add a manual switch.

The electric fan can indeed do a lot. After all, many cars have only an electric fan.

If your AC is truly out of commission, and you don't plan to repair it, have you thought about removing the condenser?

Well, I want to repair the A/c soon, the only reason it doesnt work is because I dont have the line that hooks from the pass side of the condenser to the top of the compressor (long story )

Since I'm not even sure that fan works, I was thinking about buying a new fan and putting it there, and Just wiring it to a switch.

Also, I was thinking, that for low speeds, it'd be a good thing to have a fan (or 2) in b/w the grill and the condenser to pull air into the fins, and then the fans on the motor side would pull the air into the motor compartment, giving it better cooling.

Would that only work if I got rid of a/c?

The more i think about it, the less I want my A/C !

What year, open or closed system ??
Low speed overheats are usually the fan clutch on the mechanical fan, high speed overheats are usually the radiator not able to put enough coolant thru.
Thats pretty much cover both open and closed systems.
The closed has two more issues, first is the plastic tank the second is the cap which is a pressure cap. When it goes bad [either tank or cap] the system cannot pressurize the system and it boils over.

Another question, how did you check your fan belt tension after replacing the water pump ?? The 'It feels right' don't cut it...

93 = Open System

And I'm thinking its a combination of Aux fan / Belt Tension / Burping of the system.

Does anyone have al ink to, or can explain the correct procedure on how to burp the system?

And how do you check the tension of the belt Rich?

First burping the system, easy way is to get the nose uphill a bit and open the cap. Fill the rad up to the top of the neck with the engine running. If it looks like fizzy green soda then you have air in the system.
Did you use a Jeep thermostat with the bleed hole in it and install that bleed hole facing the 12 O'clock position when you put it in ? If not pull the stat and either replace with a jeep one or drill a 1/8 hole in the flange.
Keeping the coolant up to the top of the neck wait for the thermostat to open then as the coolant goes down add more [50/50mix], keep doing this untill there are no more air fizzies in the coolant. While I am doing this I usualyu blip the throttle a few times to get the coolant moving a bit faster and maybe force some air out of the areas that don't flow quite so well at idle. It takes about 20-30 min to do this and each time you pour new cold coolant in the thermostat is going to close, be patient it will reopen. When I get down to the wire I use one hand on the throttle body to increase the idle and top off the radiator then quickly put the cap on. The system will pretty much finish bleeding itself over a few days of the remaining air. Also clean out your overflow bottle and the hose that feeds it, they can get clogged with old stuff and fill it to between midway between cold and hot. One bad overheat can destroy a thermostat so if you really overheated bad you may need to replace it.
As for belt tension I use a Krikit II that I got at NAPA, fits in your pocket and cost about $14 or so. New belt [defined as one that has been run for LESS than 15 min] is 190lbs, used belt 160lbs. I measure tension to the left of the PS pump.

Thanks so much man!

And it did spike REALLY hot, maybe i need another new thermo

Not to hijack here, but how do you know if you don't have air in your system. I tried this method, I let it idle for about 10 minutes or so after the thermostat opened and there were no air bubbles, but coolant was slowly dripping out of the filler neck. I think that means I'm good, but I just wanted to make sure.
Thanks

If you have air in the system it will expand and force coolant out the filler neck. Just a feel I have developed over the years, thats why I blip the throttle few times to try to get the coolant flowing thru faster when I'm bleeding it, to have the pump pull thru coolant from the rad. If you leave the cap off any air that is in the coolant in the radiator will eventually escape, like soda going flat, thats one of the reasons it takes so darn long. If there is air in there the pump will do a nice job of blending that air back in which is why I like to really top the rad off just before I close the cap. With the normal overflow working right it will eventually find it's correct level.
I'll be doing mine this weekend, got new hoses and stuff, thats if it does not rain. Reminds me, need pickup 6 gallons of distilled water, we're doing all three this weekend. That coolant in the TJ's smells positively foul.

Buy a new $40 clutch for the fan. You can get these at any auto parts store. I replaced all the same things you did, still overheated because I thought the clutch fan seem Ok. Mine's a '96, too. I replaced the clutch, no more overheating. Keep your OEM aux fan, too. It's a good one - on your '93, it should be the newer model fan. Also, the ECU should turn the fan on at 218*, if not, put it on a toggle, and then you're in control.

The clutch fan is merely a month old. Not replacing it again.

When you start it up cold does the mechanical fan 'roar' and then quiet down ?
Mine and others I know do as it engages initially till the fluid levels out in the fan clutch assembly. If yours does not it may have been bad NIB...
Get something smokey and put it in front of the grill, see if the fan is drawing in air...

Just replaced my radiator too. At idle at a stoplight I hit 215 before I cut the AC off. Looked under hood and I had forgotten to plug in the electric fan. Yes the little elec. fan does make a difference. Plugged it in and now I get 195 to 200 all the time with an OEM 195 t-stat.