Outer Limits 4x4 Board

My viscous fan was checked as part of the fault finding for an overheating motor, it seemed to kick in as the motor got hot and was stiff to turn by hand, and when a piece of card was jammed in it while the motor was running it almost stalled out the motor. As such it was dismissed as the not being the problem however I decided to repack it today just in case as I already had the tubes of silicon on hand. It has made a big difference in keeping the motor cool on the highway and hills, but time will tell for sure as I put a few more miles on it over the next week.

This might have been done before, but I thought that someone could use the following procedures for repacking a viscous fan clutch after having done it myself today. This is the procedure for a 1HZ 75 series truck, but I am sure it is similar for others

1.Loosen alternator, remove fan and shroud being careful not to hole radiator or damage fins.

2.Unbolt plastic fan blades from viscous hub.

3.Place fan hub in vice with front of hub facing up (side that is to front of truck with fan in car), preferably with alloy fins sitting on top of vice jaws and clamping on to the pulley flange so that the hub can be spun in situ later.

4.Undo 8 screws on face of hub USING AN IMPACT DRIVER!!!!! Or you will strip the Phillips heads and have to hacksaw a blade cut into the tops.

5.Gently prise off the top half of the hub, keeping the lower half level. (mine came off with a few light taps on a small blade screwdriver.) Note the condition of the rubber o-ring and make sure it wasn’t damaged in getting the halves apart.

6.Take a tube of viscous fan silicone from Toyota, and squeeze it into the four holes on the inner surface of the hub till it is full. Intermittently rotating the hub on the bolt flange to work it in to the internals. Make sure it is full and won’t take any more, then put some more on the top for good measure.

7.Reassemble and test. It should be noticeably tighter to spin, and the screws should be tight!!

8.Reassemble your car and test drive.

9.Strangle the muppets who told you the fan was fine and made you change every other component in the engine bay and change the thermostat 4 times.

If any of you gurus out there have any tips to add or corrections to make, please feel free as I am only quoting the job that I did today.

Hope this helps someone out there.

MILO

P.S. my fan took 2 whole tubes, so that might give you a bit of a guideline as how many to get from toyota.

g'day did toyota tell you to fill the hub??
cause I think you find that over filling the hub will stop it from "cycling" in other words it will behave as if its locked up & turn all the time.
the way they are designed to work is the bimetal spring senses heat & opens a port in the hub letting the fluid into an area which causes the hub to lock up as the fluid thickens .
when it cools the spring closes the port & the fluid is spun out of the strategic area buy centrifical force & the hub free wheels again.

not toyota exactly. it was a toyota mech i met at landcruiser. I will however call my local dealer service centre and see if it can be over full. If so it might be masking a problem in the motor by running too much.

anyone else got an opinion on this? Dumbdunce perhaps?

cheers

yeh rock would be good to have another opinion ,
is the fan free wheeling?
you should hear it when you start up cold & give it a few rev's say 1500 hold it constant for several mins u should hear the fan spinning ie pushing alot of air & as the fluid is spun out the fan should start to free wheel & go quiet again??

hey guys

rang Toymota today and asked if it is possible to overfill the fan. The mech said it's not possible. I checked today, you can still hear the fan kick in when driving, but it's operating a little more than it was. it still freewheels when cold, but it's a little stiffer than before, however i don't really have a frame of reference as was 15 years old before i repacked it.

I need to repack my fan (and probably replace the seal as all of my fluid has escaped....)

How much did the fluid cost, and is it just over the counter stuff?

rockcrawler31 wrote:hey guys

rang Toymota today and asked if it is possible to overfill the fan. The mech said it's not possible. I checked today, you can still hear the fan kick in when driving, but it's operating a little more than it was. it still freewheels when cold, but it's a little stiffer than before, however i don't really have a frame of reference as was 15 years old before i repacked it.

ive read a tech on this before and if you have the coupling in half with one of the sections flat on the bench you fill it to the brim and then oput the other half on. This is the correct level of fluid required.

you can overfill some viscous fans...... Toyota is the only ones that have user serviceable couplings, thats why Toyota are the only ones that sell the oil, to my knowledge anyhow. The coupling on the Patrol was buggered..... and on the coupling, there is a small spigot, no hole or filling screw, so i drilled it 1/8" and used a syringe to squeeze the oil in (done the same thing on a couple of passenger vehicles also) then screwed in a self tapping screw with a small amount of silastic on it. The fan now works great!! but it works too well... and it roars it's tits off all through the rev range now, hot or cold Usually, one 10ml tube of oil would be enough to get the coupling working properly ( i used 2 in mine)... saves you spending over 100 bux on a new viscous coupling.

RoeDao wrote:...Toyota is the only ones that have user serviceable couplings...

Some Nissan ones are serviceable - TD42 (Diesel) I believe. There's a few posts in the Nissan Section.

The old one from my V6 Rodeo is serviceable too.
Dont know what brand it is though.

of4x4 wrote:

RoeDao wrote:...Toyota is the only ones that have user serviceable couplings...

Some Nissan ones are serviceable - TD42 (Diesel) I believe. There's a few posts in the Nissan Section.

yup.

and TB42 ones are swappable with VL Commodore.

I did this on the weekend on my 80 series with 270k on the clock. Looked like it had not been touched before, make sure you are careful not to strip the thread off the nuts, the bolts seemed awfully damned soft!

bogged wrote:

of4x4 wrote:

RoeDao wrote:...Toyota is the only ones that have user serviceable couplings...

Some Nissan ones are serviceable - TD42 (Diesel) I believe. There's a few posts in the Nissan Section.

yup.
and TB42 ones are swappable with VL Commodore.

Nope, the TD42 and RB30 are the same bolt hole patterns Bruce, the TB42 petrol is different.
Regards Andrew.