Fan Clutch Replacement

[RichP]

Thanks for the explanation Rich. You've seen me posting here alot as I am still on my discovery since the aforemetioned accident. I was looking at my fan spin and I'm not sure if it is still true. It occurred to me that the reason the fan clutch may have failed is that the radiator smacked into it when I was backed into by a Chevy Blazer. If the fan is also slightly out of whack that could cause premature clutch failure as well, right? So I figure why not replace the clutch and fan at the same time. Only problem is that after doing research, it looks like the dealership is the only source for a stock fan. Oh well, ya gotta do what ya gotta do.

Get a fan from a boneyard. Find one that was rolled and you might even get a new fan clutch to go with it. After dealing with them for quite a few years one thing I noticed about them. When the engine is cold, first start of the day, the fan clutch is fully engaged and the fan 'roars' for about 60 seconds or so then quiets down as the clutch takes over. On every bad one I have had it won't do this and just stays quiet. It is anecdotal information but it is something that I have observed on my last 5 vehicles. You could try a flex fan on a fan clutch but I dont know how it would work, those clutches are designed with a certain minimum mass of the fan in mind, the flex lites are very light, about a third the weight of a steel fixed fan, so that may have an affect on the operation, good or bad I don't know but it will behave differently.

 

[yardape]

Unfortunately I don't have boneyards conveniently nearby but I did think of that. The problem with mounting a flex fan to a clutch is that the center hole of the fan is not large enough to clear the centershaft of the clutch for mounting. I'm probably goint to be impatient and install it today once this repair guy leaves my house. Thanks for all your help,... and now that you metion it I remember the "60 second roar" that I no longer hear!

 

[Fudd]

^^^ where in MD are ya? I've got a stock clutch fan you can have cheap, I'm in Winchester VA

 

[yardape]

Too far I think not to ship: Gaithersburg

 

[RichP]

Too far I think not to ship: Gaithersburg

Far and maryland in the same sentence, sheesh, I've driven further for a couple of slices of pizza for a late nite snack LOL....

 

[yardape]

I guess that's why you're from EFFORT. :laugh3: I don't have that much,... but the clutch is in. Now to go heat it up and see what happens.

 

[yardape]

ARGHHHH!!! No change!

Running at about 200 degrees continuous while moving which is better than prior to the accident. Then, when I come to a stop for any considerable length of time the temp starts to rise to about 220 degrees. Then the electric fan kicks in which I assume is a function of the coolant temp sensor. Am I correct on this? Its not even all that hot outside,... only 71 degrees. What's going to happen when the outside air is 90? Shouldn't the engine/cooling system be able to hold its own without an assist from the electic fan? That's for the A/C, right?

Nor do I hear the mechanical clutch kick but don't know if I would or should. I am assuming that since it is spinning it is freewheeling or operating properly?

 

[RichP]

Get back to basics, did you burp the sytem ? Put the correct amount of coolant in the overflow so it does not suck air back in ? How old is the pressure cap ?
And the big one, is the fan facing the correct direction It should be blowing BACK over the motor, not into the radiator.... The low speed over heat is the classic of the fan clutch. Unless I have my A/C on my aux fan never comes on either in traffic or crawling in 4lo 1st up a hill...

 

[yardape]

Much to be explained and so little time. This car was in an accident. The body shop replaced the radiator. I sent it back when I discovered it first overheating. They found an air pocket. It was a little better but not fixed. Took it to my mechanic who replaced the themostat. He showed me how the old one was bent and the center section showed signs of rubbing against the outside. This repair brought the temp down to 200 degrees. The fan has never been taken off except by me this afternoon. It went back on the same way it came of but I will double check it. How do you burp the system? My mechnic said he filled the coolant after installing the thermostat through a funnel placed into one of the hoses in the thermostat housing. The coolant bottle has enough coolant in it. TIA

 

[RichP]

For bleeding the system you remove the rad cap, start engine and fill it to the brim with 50/50 mix, now wait till it warms up and the thermostat opens. The level in the rad may go down, top it backup, then look for fizzy soda looking coolant, thats air well mixed into the coolant, just let it run and keep it topped off so you can see it, the air will seperate. Once the coolant is a uniform green color with no fizzies in it that usually means the air is out. From then on the overflow bottle should take care of any residual over 2 or 4 days of use.
Did the new thermostat have a hole in the flange ? if so that hole should have been at the 12 O'Clock position, it's a bleed hole and helps remove air trapped in there and also allows a minute amount of coolant to flow when it's cold but it is mostly for air. The OEM dealer ones have them and thats what I buy so I can't say if others have them. Some that don't the owners here have drilled one.
The other question I have, was the fan belt removed ? If so how was it retensioned ? A NEW belt defined as one used less than 15 minutes gets set to a tension of 90lbs, a USED one defined as one used more then 15 minutes gets set to a tension of 70lbs. Most peoples 'best guess' on setting the tension without a tension gauge [the old fashioned twist it and if it turns half way] are usually off by about 40lbs. You also have the other possiblity, the pump vanes are shot, this usuall happens when over a period of years the people changing the coolant use tap water with a high mineral/chemical content that eats the vanes on the pump.

 

[yardape]

Rich you've been very helpful and patient and I appreciate all the time you've taken writing. The pump was replaced a few years ago so its not that. This Jeep DOES have 140,000 on it. I keep harkening back to the fact that there were no problems prior to the accident. I have to take my son to soccer tomorrow morning so I may or may not have the opportunity to open the radiator and top it off as you suggested before we leave. But hopefully Monday if not then. Thanks.

 

[RichP]

Rich you've been very helpful and patient and I appreciate all the time you've taken writing. The pump was replaced a few years ago so its not that. This Jeep DOES have 140,000 on it. I keep harkening back to the fact that there were no problems prior to the accident. I have to take my son to soccer tomorrow morning so I may or may not have the opportunity to open the radiator and top it off as you suggested before we leave. But hopefully Monday if not then. Thanks.

Try to point the nose of the jeep uphill, just a bit.

 

[yardape]

With the engine cold, I opened the radiator cap and the coolant was topped off right up to the cap. I started the engine and within a minute I had coolant running over out of the radiator onto the ground. Needless to say I turned it off and recapped it. Any other thoughts? Should I have let it keep running?

 

[RichP]

It is not supposed to do that, when the system gets to op temp the coolant expands and pushes the pressure cap up and vents expanded coolant into the overflow tank. At that point the system is pressurized to whatever pressure the cap is. When you shut it down the system gets hotter for a few minutes then starts to cool down, it then pulls the coolant back in that it pushed out, it generally does not pull in more than it can take as fluids don't compress well. However I'm thinking that if you have air in it the air could expand faster than the coolant and push it out. Usually when the tstat opens the level in the rad goes down momentarily then comes back up. You can do the same thing by blipping the throttle with your thumb which is what I do a few times when burping it, the added momentary pulses of blipping the throttle can force any trapped air out.
I hate that dog leg on the radiator.

 

[yardape]

What's puzzling me is that I have no way to know if the new fan clutch I installed is actually working since it doesn't do anything different than the old one. I start the engine, it spins or freewheels or whatever its doing, the car overheats and I don't ever hear anything click in not does the fan seem to boost its speed. I also don't hear that wooshing sound at startup that we talked about. Is it possible I bought a bad fan? I believe there is a procedure using a thermometer pushed through the fans shroud for for testing it. I'll have to check this out.

 

[SimpleXJ]

It is normal for the radiator to spill some collant when you pop the cap and start the engine. The electric fan only comes on with the A/C UNLESS the temperature reaches a high level (usually 3/4 mark on the guage) in which case the thermostatic switch will turn on the elctric fan - A/C or not. I have 4 XJ's and on every one of them this electric fan "ON" temp is different.

The fact that you have replaced the rad, the clutch. the fan and the 'stat with no resolve to the overheating issue makes me think you have a restriction somewhere in the cooling system. Have you flushed it? Like Rich said, it could be the pump also. Replace the rad cap too.

When burping the system (take off rad cap and let engine run) make sure you have the heat on, to ensure you get the air out that may be in the heater core.

 

[yardape]

The water pump is no more than 2 years old. I'm still not sure that the new fan clutch is working properly. The electric fan kicks in but not the mechanical one that I can tell. The mechnical fan clutch works on under hood temperatures near the radiator as opposed to the A/C fan works off of coolant temp right? The problem is that the local temp here is really not hot enough yet. One day its 65 and the next its close to 80. That's when I really had a problem. The body shop that installed the rad and the mechanic couldn't even make it overheat until I broought it back the second time and they ran it with the hood closed rather than open. Everything really points to a bad fan clutch still particularly since I've never actually witness it kick in. Hmmm unless the accident crimped the lower rad hose when it pushed the radiator in.

 

[Fudd]

At low RPMs your fan clutch should engage, otherwise the fan will just freewheel. You can test this by touching a stick in the fan at idle it should break the stick if its working if its not, the fan will stop without much resistance. (I use my hand but of course I'm not all that bright lol ) BTW use some common sense w/ the stick size, don't stick a 2x4 in there lol

 

[dyna]

I just went thru this all with my 95. The new fan clutch runs all the time at idle as its supposed to. Sounds like yours is no good. I used an Imperial brand. Ive had bad luck with Hayden stuff. Testing was a waste of time and inaccurate. My radiator is less than 2 years old and was 40% + plugged, I had it rodded.I also installed a trans cooler. I now never see temps over the middle mark of 210 pulling hills in 100 degree heat here. Previously I was running at 210 to 240 with unexplained swings in temps and idling it would get hot enough to send the electric fan on which would cool it temporarly.

 

[SimpleXJ]

There is no obvious click or anything when the fan clutch enguages like there is with the AC. You won't hear a thing. However, the lack of the cold "60 second roar" does point in the bad clutch direction. You are correct in thinking that the mechanical fan works off the temp in the engine bay, whereas the electric fan runs off the temp sensor. Do as Fudd said - take a weak stick (or just wear some heavy welding type gloves) and see if you can stop the fan at idle after the jeep is warmed up. If you can.... it ain't working right.