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Fan clutch stiff

R

Racing4funn

NAXJA Forum User
Location
Chattanooga Tn
Its a lot stiffer than I think it should be.. Its got 120k on it and has been under water a few times. Is there a way to clean it? WD40? Something.. ITs a wheeler only and I dont want to spend $40 on getting a new one.
 
No need to clean the thing - and it's supposed to be fairly stiff. And, it gets stiffer as it gets hotter (yes, I know what that sounds like...)

If you really feel the need to clean it, a quick blast with carburettor cleaner should serve - but I've never felt the need.

In daily service, a fan clutch on our XJs is good for four to five years. Intermittent use (like your trail rig?) will be considerably longer, but I can't really give an estimate on time.

However, I'd probably just not worry about it.
 
Racing4funn said:
I guess but I believe that when jumping on the throttle, power is being robed because the fan should be slipping and I dont think it does or will
Click to expand...

The fan clutch is a fluid coupling - it always slips. How much is a matter of temperature.

The colder the clutch, the more it slips. Period. The hotter the clutch, the less it's supposed to slip. Period. It's a thermal clutch not a centrifugal clutch.

Unless you're running some variety of street racing rig, the power loss is going to be nominal anyhow - so why worry about it?
 
5-90 said:
The colder the clutch, the more it slips. Period. The hotter the clutch, the less it's supposed to slip. Period. It's a thermal clutch not a centrifugal clutch.
Click to expand...

So when its cold and it takes most of my finger strengh to move it, that means what? It wont move at all hot? That dosent seem right and thats why I made this post.. Maybe I should find another Cherokee and check theirs out since Im paranoid.
 
Actually, mine does the same thing, which I thought was odd.

When cold, first thing in the morning...it takes a lot of force just to make it spin...less than 1/10 of a rotation using fingers.

In fact, it is easier to spin when hot and driven for a while...still some resistance, but spins about 1/4 of a rotation, more or less.

Seems to be more resistance when cold than hot...what does it all mean?
(am I in bizarro world?)
 
This is normal... They are stiffer when cold because they are designed to spin at a higher rpm at engine start, then slip to normal at operating temp, and tighten back up as temps rise or rpms rise. normal. :)
 
Well unless you have a weak finger, it shouldn't take almost all of your finger strength to spin the fan when the vehicle is off.

At least I've never come across a fan with a clutch that was this difficult to spin!
 
It just means he has a good fan clutch... the reason a good fan clutch is engaged when the engine is off and cold is because the fluid drains into the working area when the engine is shut off. Actually it's probably more because of sheer physics than design... The fan clutch will slow down shortly after startup as a result of a pumping action produced by a difference in speed between the shaft and the body of the clutch.
 
Never heard of anybody worrying about it being too stiff and wishing for a limp one.
The fan clutch in mine is fairly stiff in general (all temperatures), when cold I figure the silicon settles to the bottom and makes it stiff. During normal operation, it is still stiff but nor nearly as stiff as it is before startup and some revolutions or after the motor heats up.
My only real complaint is the noise, it does whistle some, even at idle. It likely wastes a few horses, but has never really affected performance any that I've noticed. Since installing the new stiff clutch, my aux fan has never come on once yet ( the temperatures here are fairly mild). With the old limp clutch the aux fan would come on after 5-10 minutes of low RPM operation most every time (unless it was winter).
 
The only reason Im even playing with it is because the motor mounts broke and the fan jumped threw my radiator. Fan physically looks good. I got to thinking about how stiff it was because I get into situations that I have to get from an idle to almost the limiter very quickly and it usually dosent jump fast enough. SO if the fan was in lock mode or close to it then its going to kill my quick rev. I will check it then its hot and see what the difference is.. Ultimately I could go with an electric fan but I dont want to roll the dice on it cooling..
 
On the old Dodges you could adjust the temperature setting. The Bi metal spring (coil) in front. Disconnect it from the valve shaft and turn the shaft 180 degrees. I sure can't remember which direction to rotate the shaft, likely the opposite direction of the bi metal coil twist to make the valve open at a higher temperature. Yours may have been assembled wrong at the manufacturer.
I've never tried it on anything after around a 1975 Dodge truck.
When I adjusted one, it was always to make it stiffer and hopefully improve low RPM cooling.
 
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