Fan Clutch Testing and Repair

[mdbrandy]

I'm starting a new thread, since the other one discussing cooling kind of went off on a science tangent....

I drove home tonight (about 10 minutes, 7 miles), and the engine temp gauge indicated that the coolant was up to temp. Upper radiator hose hard and hot. Open the hood with the engine still running and look at the fan. Spinning, but kind of seemed to be slower than it should be. Turned off the engine and immediately tried to turn the fan by hand. I could spin it with one finger. Sound bad? The factory manual is useless for this - gives you the theory of operation and then just says to check for oil leaks and bent bimetal, and replace as a unit. Is this thing really repairable?

[2ManyZs]

Yes, you can take it apart and refill it with oil... and I'm still looking for the tech article that tells all about it.

Sounds like the oil has leaked out and it isn't locking up like it should.

FWIW, the tech article isn't in any of the Z mags, so I'm not sure where I saw it, I'll go back and look some more tonight... I know I just saw one recently...:stupid: :cross-eye

[Bambikiller240]

Originally posted by 2ManyZs

Yes, you can take it apart and refill it with oil... and I'm still looking for the tech article that tells all about it.................FWIW, the tech article isn't in any of the Z mags, so I'm not sure where I saw it, I'll go back and look some more tonight... I know I just saw one recently...:stupid: :cross-eye

Keith:

When/If you find it, could you post it to the Technical Articles section, or if it's a link to a website, email the link to me and I will rewrite it, if needed; so that it can reside in our club database.

Howz your camera? Hint, Hint!

[ZmeFly]

Pics can be seen here http://www.pbase.com/bronte/fan_clutch

Here are the instructions:

A fan clutch is supposed to be a fluid coupling device that allows the fan to rotate less than the engine speed.

Unfortunately, a fan clutch can slowly empty it's coupling oil overtime and often seizes. (the oil also can gel/thicken and grab). This means that it turns as fast as the engine! It results in:

extra wind

extra cooling

false temp sensor readings (they are in the high velocity wind stream)

delayed thermostat opening (it is cooled too much as it is in the high velocity wind stream)

lots of noise

possible damage to water pump due to unbalanced fan and torque on the water pump shaft

Check for a seized fan clutch it by opening the hood with engine running in neutral.

Rev the engine and listen/watch fan. If you get a wind storm and windy sound from fan area then your fan is seized.

There are three solutions:

1. Replace Fan Clutch with new one (~$70)

2. Recondition Fan Clutch (~$5)

3. Remove fan clutch + fan and replace with 12V electric fan (~ $50-$200)

I just reconditioned mine. It went pretty easy. Here is what you need:

10mm, 12mm, 13mm wrenches

Knife

Rags

Brake/TB/Carb Cleaner or other solvent

Oil

Lacquer Thinner

Here is how to do it:

loosen alternator (13mm and 12mm bolts on mine)

remove four 10mm nuts holding fan assembly to water pump pulley

remove fan assembly

Remove four long 10mm bolts that hold fan to clutch (note the old oily dirt in center ring of plastic fan.

Wash fan in soapy water (paint it if you feel spanky)

Remove four short 10mm bolts from rear of fan clutch

Use knife to pry front and back halves apart (they are stuck together with suction)

Drain remaining "honey" oil inside

Remove O-ring and recondition with lacquer thinner

Clean/flush aluminum halves with brake cleaner or similar

Refill back half with oil and a few cap-fulls of lacquer thinner.

Reassemble

Check for leaks

Reinstall

Check for leaks and proper operation

Hope this helps you out.

[2ManyZs]

Well, I can't find it....:stupid: I've gone through every issue of SportZ and ZCar magazine page by page for the second time and don't see it....so now, I don't know where I saw it....

What ZMeCruise posted is pretty much what I was looking for, except the article I read told which viscosity oil was the best to use....

[MikeW]

Originally posted by ZmeFly

Check for a seized fan clutch it by opening the hood with engine running in neutral.

As if you'd open the hood with the engine running in gear?

[abas]

Not strictly relevant here but I understand that the really early fan clutch ( that goes with the metal fan) cannot be rebuilt as it doesn't have 2 halves that are bolted together and therefore doesn't come apart.

FWIW

Andrew

[tanny]

What's the process for reconditioning an o-ring with lacquer thinner? Victor.

[peterc]

Just a little something to add to ZmeFly's excellant response. Before you go to the bother of dismantling, cleaning and re-assemblying the fan clutch, make sure that the shaft connecting the blade assembly to the clutch assembly is still tight.

If your fan 'wobbles' (check only with the engine OFF!!) and is unusually noisy, even at idle, then the internal non-replaceable bearing is worn and the unit will need to be replaced. All the cleaning and oil replacement in the world won't make it work any better. Been there, done that .

Cheers,

Peter

[mdbrandy]

ZmeFly, thanks for the tutorial. I'll jerk the fan off my '78 parts car and see what I can do to rebuild it. If that goes well, I can swap it out with the problematic one on the running '78. I like $5 much more than the costs for the other solutions!

[Bambikiller240]

Wish we could find out what viscosity of oil to use for this purpose. I'd think that there would be significant performance differences between the various multi-wieghts, and straight weight oils that could be chosen, especially if they are "watered down" with lacquer thinner.

[mdbrandy]

Originally posted by Bambikiller240

Wish we could find out what viscosity of oil to use for this purpose. I'd think that there would be significant performance differences between the various multi-wieghts, and straight weight oils that could be chosen, especially if they are "watered down" with lacquer thinner.

Very true. Obviously, the "normal" fix for this is replacing the clutch. I have the factory manual and about 5 other manuals of various types on Z's, and NONE of them even gives a good diagnosis section for the fan cluch, much less how to repair it or any actual data on it. They all have the same very nice drawing, and a description of the theory of operation, but nothing else. Oh well, unless the real data surfaces, then using the wrong oil weight can't hurt it much, since it doesn't work anyway! Just a waste of time to rebuild if it doesn't work after...