[me3@neuralfibre]

This might interest some of you.

Tuning and Understanding your Toyota Viscous Fan Clutch | Paul's esoteric meanderings

It's an expansion on Franks.

Thanx
Paul

[cary]

Great writeup. You will find a ton of information about calibrating the fan clutch on the 80 forum. Here is a link to the FAQ. Given the 100 is a different vehicle, it may have a different calibration point.

Blue fan clutch mod

[Trunk Monkey]

I'm guessing this in on a 1HZ? Fortunately the fan clutch isn't an issue on the 2UZ.

[Utahfj62]

Originally Posted by Trunk Monkey

I'm guessing this in on a 1HZ? Fortunately the fan clutch isn't an issue on the 2UZ.

Fan Clutch on my 2UZ died tonight. New one on the way.

[spressomon]

Originally Posted by Utahfj62

Fan Clutch on my 2UZ died tonight. New one on the way.

Had to replace mine a couple years ago.

[Trunk Monkey]

Originally Posted by Utahfj62

Fan Clutch on my 2UZ died tonight. New one on the way.

It's the snorkel, that caused it.

When I say "isn't an issue", I don't mean "doesn't ever fail". Just meant it wasn't so necessary to refill with different viscosity fluid, etc.

[Utahfj62]

Originally Posted by Trunk Monkey

It's the snorkel, that caused it.

When I say "isn't an issue", I don't mean "doesn't ever fail". Just meant it wasn't so necessary to refill with different viscosity fluid, etc.

Yeah - sure you did. You jinxed me - Pecker. It's your fault it died. I read this thread - truck starts making noise three days later - BAM. Fan Clutch dies. I blame Trunk Monkey and I know you have Snorkle envy.

I'll post and extenstive detailed write up of the replacement. Here is a preview.

"Removed siezed fan clutch. Installed new one. Done."

[hks3sgte]

Anyone know if the Tundra has a different clutch? It sure sounds louder than the 100.

[Utahfj62]

Originally Posted by hks3sgte

Anyone know if the Tundra has a different clutch? It sure sounds louder than the 100.

I believe it does have a different one. When I picked up the fan clutch yesterday from the local Toyota delearship - the parts guys stopped and questioned if I had the right part. They said it didn't look right - they thought I ordered one for a tundra. Told them it was for the 100 - they said "oh yep this is the right one."



I put the new fan clutch on last night. Took me about 1.5 hours. Pretty straight forward remove and replace. I had to remove the fan shroud to get the old one out. Only tricky part is you undo the bolts for the fan clutch holding it to the pulley and the remove the bolts for the fan shroud and pull both out together. Same thing for install - you have to slide the shroud and fan in together inorder to make them fit. Bolt up the new fan clutch first, then the shroud.

Easy job. 1 banana

[spressomon]

Originally Posted by Utahfj62

I believe it does have a different one. When I picked up the fan clutch yesterday from the local Toyota delearship - the parts guys stopped and questioned if I had the right part. They said it didn't look right - they thought I ordered one for a tundra. Told them it was for the 100 - they said "oh yep this is the right one."



I put the new fan clutch on last night. Took me about 1.5 hours. Pretty straight forward remove and replace. I had to remove the fan shroud to get the old one out. Only tricky part is you undo the bolts for the fan clutch holding it to the pulley and the remove the bolts for the fan shroud and pull both out together. Same thing for install - you have to slide the shroud and fan in together inorder to make them fit. Bolt up the new fan clutch first, then the shroud.

Easy job. 1 banana

1 unless one or more of the fan clutch nuts that hold the clutch/fan to the pulley bracket can't be removed . Other than a large channel lock there isn't any good way to hold the pulley tight so the nut(s) can be removed. Brilliant design: Not!

Of all the GM's I have owned I NEVER had to replace a fan clutch...nor the silicone fluid that makes one work. This will be the third fan clutch (actually if I ever get the effing thing off I'm just going to refresh the silicone within) in 3-years.

Toyota certainly has some smart designs...unfortunately the fan clutch isn't one of them .


Gotta get back to working on this issue.

Rant over.

[Tools R Us]

Originally Posted by spressomon

...
Toyota certainly has some smart designs...unfortunately the fan clutch isn't one of them .
...

I have worked on a ton of vehicles and IMHO the Aisin clutch is the best design that I have seen. Have never worked on a ’100 clutch, but have done most other Toyota clutches. In my experience the clutch is a great design, compromised by thin fluid, probably to make a smooth, quiet running motor and eek out every CAFE fraction of a mpg possible?

The thin fluid is just adequate for normal operation. When run harder than normal or in hot temps, it’s sheared hard, this heats the fluid, causing the viscosity to be reduced, lower viscosity has less drive/shearing ability, so it has to work harder, so it gets hotter, repeat, until the fluid is dead. It’s not “an ’80 problem”, it’s common among all of the later model Toyota’s that I have worked on.

By changing to higher viscosity fluid, the fan has much more drive, so when it comes on it does the job and turns off, much shorter cycles. The fluid is less stressed and lasts much longer. The main benefits are, reduced A/C vent temps when idling, higher ultimate cooling capacity to overcome any “oops moments” and longer fluid life.

Swap in some 10,000 cst fluid and report the changes, my bet is you will notice a big difference. I don't agree with adjusting the valve colder, don't want the fan engaged more often, want to more effective when it's needed. Adjusting the valve cooler is like installing a colder thermostat, it starts working earlier, more often, but doesn't add any cooling capacity.

[cruiser100]

Has anyone ever put an electric Flex-a-lite on their rig?

I replaced the clutch driven fan on my '99 Expedition with a dual Flex-a-lite and was hyappy with the set-up.

[spressomon]

Originally Posted by Tools R Us

I have worked on a ton of vehicles and IMHO the Aisin clutch is the best design that I have seen. Have never worked on a ’100 clutch, but have done most other Toyota clutches. In my experience the clutch is a great design, compromised by thin fluid, probably to make a smooth, quiet running motor and eek out every CAFE fraction of a mpg possible?

The thin fluid is just adequate for normal operation. When run harder than normal or in hot temps, it’s sheared hard, this heats the fluid, causing the viscosity to be reduced, lower viscosity has less drive/shearing ability, so it has to work harder, so it gets hotter, repeat, until the fluid is dead. It’s not “an ’80 problem”, it’s common among all of the later model Toyota’s that I have worked on.

By changing to higher viscosity fluid, the fan has much more drive, so when it comes on it does the job and turns off, much shorter cycles. The fluid is less stressed and lasts much longer. The main benefits are, reduced A/C vent temps when idling, higher ultimate cooling capacity to overcome any “oops moments” and longer fluid life.

Swap in some 10,000 cst fluid and report the changes, my bet is you will notice a big difference. I don't agree with adjusting the valve colder, don't want the fan engaged more often, want to more effective when it's needed. Adjusting the valve cooler is like installing a colder thermostat, it starts working earlier, more often, but doesn't add any cooling capacity.

That's what I am going to install: 10,000 cst fluid. However there seems to have been a run on the stuff here in Reno

[campoj2]

Other than an overheat condition or a temp gauge that is not where it's supposed to be, how do you know if you have impending clutch failure about to happen?

[spressomon]

Originally Posted by campoj2

Other than an overheat condition or a temp gauge that is not where it's supposed to be, how do you know if you have impending clutch failure about to happen?

First clue would be cool-ish (as in not cold) air conditioning air at low speeds (assuming all other aspects of the A/C are OK). When the engine is hot you shouldn't be able to turn the fan easily if at all.

Second clue would be water temp running hotter than normal at low crawl type speeds (you're only going to be able to detect this with a Scan Gauge II or similar as the OEM temp gauge is 'buffered'.

[Utahfj62]

Originally Posted by spressomon

First clue would be cool-ish (as in not cold) air conditioning air at low speeds (assuming all other aspects of the A/C are OK). When the engine is hot you shouldn't be able to turn the fan easily if at all.

Second clue would be water temp running hotter than normal at low crawl type speeds (you're only going to be able to detect this with a Scan Gauge II or similar as the OEM temp gauge is 'buffered'.

I run a Scangauge II on my truck - which operates consistantly between 194 and 198 on flat normal day to day. Going up over hills or pushing it - the hottest it ever gets is 200 to 202. Never higher. When my fan clutch started going temps bumped to 198 to 200 consistantly - a slight difference but one that made me pay attention and ask why it was running warmer?

Then the obvious failure was the loud screetching the fan started making the next day. It was intermitent -but screamed like a banshee when it was making noise. Stopped the engine and sure enough you could barely spin the fan. It was on it's way to totally siezing within a few short trips.

[spressomon]

Pulled the fan clutch off; separated the two halves of the clutch; drained the fluid (not much came out...and what did come out was amber colored FWIW); let it drain for 2-days; refilled with 10,000cst silicone until full (fill, rotate, let it rest, come back, refill; repeat until full). So far today, first day testing, it work great! Nice cold A/C even at idle. This is the first time I could actually hear the fan fully engaged during take-off from a stop.

As mentioned above or somewhere: You need to remove the fan shroud and fan at the same time from the top. You will need to disconnect the upper radiator hose and of course the radiator/coolant overflow canister.

My fan clutch nuts were on there! Guess I might have been a little over zealous with those when I did the PM! Anyway I had to make a tool to hold the fan clutch pulley from turning while removing the four nuts. Essentially just a 3/4"x3/4"x7" piece of hard maple with several layers of rubber friction tape. Jam it in between the crank pulley and the fan clutch pulley and it held tight to allow me to loosen (and then reinstall and tighten on the flip side)...

[Tools R Us]

Originally Posted by spressomon

Pulled the fan clutch off; separated the two halves of the clutch; drained the fluid (not much came out...and what did come out was amber colored FWIW); ...

The fluid oxidizes with time turning amber, oxidization alone won't affect performance, so color isn't necessarily an indicator of bad fluid. In my experience the later clutches are under filled, probably shortening fluid life.

Originally Posted by spressomon

... refilled with 10,000cst silicone until full (fill, rotate, let it rest, come back, refill; repeat until full). ...

Does it "turn off"/freewheel when cool? The fluid needs to fit in the reservoir, if not it will be engaged all of the time. My refill amount for the larger clutches is ~50ml max. If it stays on all of the time, simply drain some out.

A good thread on the procedure, it's about the mini/runner clutch, but only the refill amount is different.

Fan Clutch Service