DIY Viscous clutch fan rebuild

[chrisfarru]

So my truck started overheating with AC on especially when running LPG. Only happens at slow speeds or in traffic on a hot day. Switching off the engine when warm, the radiator fan would just spin and spin freely, so I figured the viscous clutch was shot. At $250 a pop I thought I'd try and fix it. This is the video before the fix.

https://www.youtube.com/watch?v=_bQfypn9f6Y&feature=youtu.be

This is the video after reoiling it. As you can see the fan is fully engaged when the engine is warm and stops spinning as soon as the engine stops.

https://www.youtube.com/watch?v=6d1QGkNiG-Y&feature=youtu.be

Here are 2 videos showing how these clutches work.

https://www.youtube.com/watch?v=N_GkuTgJr3w

https://www.youtube.com/watch?v=3ACx7GTCn7Y

Removing it is a breeze. First unclip the upper fan shroud. Then using a 10 mm spanner remove the 4 bolts holding the clutch to the hub. To rotate the hub around and reach all 4 bolts, turn the ignition a pufffienth of a second without starting the car. Once the bolts are out, a bit of a wiggle and the fan is out. Remove the four 10 mm bolts and separate it from the fan. To separate the 2 halves there are 4 large phillips screws. Ideally use a socket wrench with a phillips attachment because they are snug in pretty tight.

[chrisfarru]

To separate the halves use a small knife and pry them open. As you can see from the pics there was still plenty of oil left and the viscosity of the oil was ok, so I’m not exactly sure why it wasn’t working. At this stage it is a good idea to test the bimetallic strip. Use a hair dryer to warm the back of the plate where the central strip is and you should slowly see the strip move and open up Hole A. Remove the rubber seal and give it a good clean. Be warned that the rubber seal is larger than its groove and will take some fiddling to put it back on. Best way is to put it in a freezer to shrink it and will then slide right in.

[chrisfarru]

Next up is draining the old oil. Clean as much as you can reach with a rag and the flip both halves on their sides and wait until it all comes out. It takes at least 2-3 hours for it to come out. The side with the bimetallic strip should have the grooves pointing downwards to drain the oil. When the oil is out completely, the shaft should spin freely without resistance. Good idea to check for any shaft play.


You will need 1 tube of Toyota viscous oil 08816-10001, they cost $12 from your local Toyota parts store. Refilling the hub with oil is easy. Just fill the 5 holes as pictured and wait for the oil to seep through while rotating the shaft. I used the full tube. Retrospectively I probably would have used a bit less than all the tube.

[chrisfarru]

While dismantling I met this small plastic thingy floating around. For the life of me I’m not sure where it came from. In the pictures you’ll see where I think it should go, but don’t take my word for it. I think it’s there to clean side holes where oil recirculates and crosses from one half to the other while spinning.


The result was good. It spins relatively easy when cold and fully locked up when engine warm. I tested it with AC on in traffic on a hot day and engine watchdog temps never went above 83 degrees. Before the rebuild I was getting temps of up to 105 and the dash temp gauge was going beyond 3/4 of the way. I will report later about any changes in fuel consumption and if the clutch fails again.

[Dicko1]

I had to do the clutch on my landcruiser 2 years ago due to an over heating issue. Turne out it was an over fuelling problem. Anyway it took about 1/2 from start to finish using the Toyota oil. Made the fan a lot less prone to spinning.

Good fotos and will be a good reference for anyone wanting to do their own.

[gavin67]

Isn't this going to fill in a lot of weekends, I for one will be doing it soon, as I think the cost of these things are getting out of control. I did all the other stuff ie rad,thermostat and belts not long ago but couldn't afford the new clutch but $20 bucks and a day on my old girl is a no brainer.

Thanks for the tutorial.

This site has saved me a fortune

[Bundyk]

chrisfarru, you bloody legend. I need to do this myself, and your thread has just made life a whole heap easier.

Thanks mate!!

[GHendo]

Well done Chris,

I've put a new fan in mine but I still have to old one and have been going to pull it apart and have a fiddle. I'll probably now set it up as a spare.

Cheers

Geoff

[chrisfarru]

super easy job. The phillips screws can be a pain in the butt without a socket wrench. I wouldn't see myself undoing them with a screwdriver.

The truck now reaches operating temps within the first kilometre and sits at 75 degrees in traffic, can't believe the difference it made. I'm lucky I didn't cook the engine, I was sick of the engine watchdog beeping my head in with temps of above 100. I am not sure how fast a new clutch fan should spin when cold but I feel it may be spinning more than it should. That's why I suggesting putting in 5ml less oil.

[Bundyk]

Its not going constantly is it?

[chrisfarru]

Nah it's not. It's pretty loose when cold but stiffens up when warm. When you first start the engine it "roars" for a few seconds but then settles down.

[Bundyk]

Sweet. Thanks again.

[Trisome]

Great info, thanks, now I have something to do next week-end.

Trisome

[Trisome]

Just did this twice....

The first time somehow the oil vanished, now I couldn't see where 18 ml of 1000 cwt oil went, the seal looked in place the bolts were tight, there were no oil smears. The second time I put some extra sealer around the rubber, and now it seems to be working perfectly.

Trisome

[chrisfarru]

Hmm that's awkward, did you notice any oil spill around the area?

UPDATE
During the first 1000 km I noticed that it wasn't disengaging as well as it should when the engine was cold. My fuel consumption went from 17L/100km to 20L/100km (on LPG). Nowadays it runs much better after 1000 km and I am getting 18L/100km. It roars on start-up then disengages after a few seconds. I notice it re-engaging when engine is warm.

Mind you when I was getting 17L/100km, the viscous clutch fan was completely shot so I was probably getting better mileage than I should have. Yesterday towing 1.5 ton in 37 degree weather, front and rear AC running full blast, driving for hours and in heaps of Sydney traffic the engine temps never went beyond 85 degrees. Before I was constantly hitting 105 degrees under same conditions. I love this fix!