Ok so I have been working on a jeep I bought for cheap over the past few weeks and it needs some love. I decided to drain and flush the cooling system after I noticed the temp start to climb a little at idle every once in awhile. After the flush and drain I noticed the electric fan not coming on (not sure if it did previously) so I decided to change the temp sensor, thermostat, and aux fan relay while I was at it.

Before changing the thermostat the temp would get to about 210-215 and drop back down but I figured it has 150k miles so it wouldn't hurt to change it. After the thermostat was replaced with a fail safe 195 I went to op-check it and the temp constantly rises without dropping. Got close to the red so I shut it off, tried again and same result.

I need help guys, I need my jeep for school.

 

Before we can give you any ideas we need to know year model and engine size since the are a few variations in the years and engine size.

 

I would guess that you have an air pocket in the cooling system, that you need to burp out......RR

 

Oh yeah sorry, 1996 4.0L. My neighbor had me run it till it got hot then hold the gas, that opened up the thermostat but now it's constantly running at about 220. Is that normal?

Also, I noticed the cooling fan relay housing is intermittent. When I just barely sit the relay in its housing the fan will kick on and off and I can hear the relay working. Are new fuse boxes expensive?

 

220 is a little high. 210 is normal operating temp for the 4.0 I would verify the temp with an I.R. temp gun aimed at the t-stat housing to make sure that you are not running to high. Also have you checked your fan clutch?

 

How do I check the fan clutch? It's just odd because it always idled at around 210 before but now that it has new stuff it's acting worse than before.

 

Try contact cleaner in the sockets before replacing the whole fuse box. Dust and junk get in. Happens.

 

With the engine off and cold the fan spins about 1/4 to 1/2 of a full turn when I grab a blade and spin it. Is that good or bad?

 

Not much help on the fan clutch. One tip is to see if it free-wheels longer after you turn it off when cold, as opposed to what it does when you turn it off when everything is fully up to temp. Should be stiffer and stop faster when it's hot.

Like RT points out, the gauge and/or it's sender could well be off. Maybe the parts store has one you can borrow for a minute? (IR temp gun). Btw the E-Fan should come on at 217*, and when the AC is turned on. Maybe on defrost as well.

 

Is the intermittent E-fan action because of the AC clutch engaging? That's normal.

 

Fan clutches can gradually go bad so under certain conditions may not do it's job 100%. If you don't know the age of it and if you can afford it go ahead and replace it. Otherwise get the motor to operating temp. Have someone turn the motor off and you watch how soon the fan stops. Also while the motor is at operating temp have someone rev the motor some. You should here a definite diff from it just idling (rush of air). Only way I knew mine wasn't getting the job done was when pulling 3mi mountain in warm to hot temps. She'd almost get to the red.

 

I will try the temp gun thing tomorrow. My A/C doesnt work and i have never seen the cooling fan come on so i dont know if it will. I do know that when i pull the relay and just barely put it in i can see the fan kick on slightly then off. I added some more coolant as i lost a little from the initalial overheat, it seemed to knock the temp down to about 215.

 

It would be nice if you could fill out your info, (maybe on a computer). Anyway I found in post #4 it's a 96. Those relays are interchangeable, you can try another one. The fan is pretty high amp. If a wire or connection is gonna go funky, that one would be high on the list.

I think power should go from 30 to 87 when 85 is grounded by the PCM. Maybe 86 gets power off the ign switch, anyway the relay will need power there to shoot the real juice up to 87.

 

Back to this topic, I decided to just replace some parts as they are pretty cheap. This thing was not very well maintained so Im sure the pump is as old as the vehicle. I ordered a Gates water pump 42004, upper and lower radiator hoses, radiator cap, and water pump inlet hose. Can you guys think of anything else I should get or do while Im at it? Is there a chance I got a bad temp sensor from the parts store, I think it was a duralast temp sensor.

 

Another update, on the way home from school today the gauge never went above the quarter mark, so about 150. What the hell is going on?