Fan Clutch

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Date: Tue, 24 Jun 1997 17:55:18 -0600
From: loki@crestedbutte.net
Subject: cooling sound
To: Toy4x4@tlca.org

James Brink wrote: 
> Could this be the radiator fan clutch engaging and disengaging?
> 
> It is normal for the clutch to engage when warm air flows away from the
> radiator towards the fan during warm days, especialy). This is how the
> fan clutch works.
> 
> If the sound is more like running water behind the dash board, I would
> check the coolant level in both the radiator and overflow tank (with the
> engine cool, of course).
> --
> Jim Brink                               1986 Standard Bed 4X4/22R/M5
> Toyota/ASE Certified Technician         32"BFG All-Terrains
> (brinkjm@earthlink.net)                 LockRight/4.10 Gears
> ********************************************************************
> TLCA# (Still Waiting)
> FOMR
> MRVMA/DESERT EXPLORERS

Jim thanks for the info, I am a little embarrased to say that I didn't
even know I had a fan clutch. Ive never seen my engine run without the
fan moving. maybe you wouldn't mind expanding on this topic a little. I
suspect the sound I was hearing was indeed this, the engine tone changed
octaves kinda, and only when the temp gauge gets to its high point. the
temp comes down, tone goes back to normal. I thought my keen perception
of the sound was some kinda oneness with the engine. looks more like
dumbness..... Rob Boyle 85 4runner

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Date: Tue, 24 Jun 1997 23:31:58 -0700
From: "aj" 
Subject: Cooling sound
To: 

That sounds like the fan clutch. It's normal.

When you first start the engine, the fan clutch is tight, so the same sound
should be heard, until you accelerate once down the street. Mine takes
about 10 seconds to go away. My last truck, Chevy, did the same thing. 

The fan clutch is designed to be tight when hot air is passing by. When
enough cooler air is passing by, it disengages sort of, to reduce the load
on the engine by letting the fan not spin at the same speed as the enging.
The fan clutch engages to make the fan turn faster when the engine needs
extra cooling, like on hot days or when idling at a light on a hot day.

I learned the pattern by swapping out what I thought was a bad one on the
Chevy, only to find that it still did the same thing. I first thought that
I was not circulating enough oil at startup and that the oil pump was going
out. Just the fan clutch doing its thing.

A J
Systems Manager, Southern California
aj@oc-net.com

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Date: Sun, 31 Aug 1997 07:27:58 -0600
From: dicknu@usa.net
Subject: Diagnosing bad clutch fan?
To: Toy4x4@tlca.org

Scott (et. al)

I have no direct experience with the fan on TOY, but when my Nissan
PU lost a fan, checked with local Nissan mechs and they said:

"With the truck cold, tie a length of "kite string" to one of the fan blades,
and the other end to some point in the engine compartment.  Then start
the car.   The string should be able to hold the fan when the engine is
cold, and a good fan will break the string with engine warm."  Was a 
good quick check for me.

BTW, I installed 2 'rebuilt' fan clutches, did NOT fix  problem.  Had to get
clutch from Nissan to cure problem!  And you CANNOT believe the
horse power siphoned off by a constantly turning fan!

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Date: Thu, 26 Mar 1998 21:03:03 -0700
From: Tony Bartlett 
Subject: Fan clutch

David, the fan will always spin.  Depending on the clutch it will be
slightly spinning (disingaged) or pushing lots of air (engaged).
To check a fan clutch this is what I do.

You could start your truck (cold) wait a couple of minutes.  A clutch
will act like it is engaged when first started because the fluid is not
evenly distributed at this time (I think I heard that from Jim Brink,
and it makes a little since).

Then using a shop rag, push the rag into the fan.  It should stop really
easy and offer no resistance.

Next get the truck up to operating temp. (or if it was overheating drive
it until it starts to overheat) and redo the check (Note:  If the fan 
clutch is working correctly it will be very difficult to stop).

I recommend buying a OEM clutch, they have dropped way down in price
since a few years ago and I have had no luck with aftermarket clutches.

Toyota Tony
http://www.digitalpla.net/~offroader


------------------------------
Mark wrote (with liberal snipping):

>my normally rock-solid temp. guage would climb a few degrees
>whenever I hit a small hill or tried to run the AC.

I think it is normal for the temp to climb when the engine is being
strained. And a hot day makes it worse. If your truck is only starting
to do it after many miles, it could be a sign the engine is getting
weaker due to carbon buildup, or normal wear.

>only idea left is the fluid clutch in the fan. How can I diagnose this?

An idea from my web-page archives:

>"With the truck cold, tie a length of "kite string" to one of the fan blades,
>and the other end to some point in the engine compartment.  Then start
>the car.   The string should be able to hold the fan when the engine is
>cold, and a good fan will break the string with engine warm."  Was a 
>good quick check for me.

>And, pardon my ignorance, but why is the cooling fan clutch driven
>anyway? Why not just run it full time?

Again from my archives:

>The fan clutch is designed to be tight when hot air is passing by. When
>enough cooler air is passing by, it disengages sort of, to reduce the load
>on the engine by letting the fan not spin at the same speed as the engine.
>The fan clutch engages to make the fan turn faster when the engine needs
>extra cooling, like on hot days or when idling at a light on a hot day.
______________________________________________________________
Barney McNamara              JENNY - 83 Toyota Short Bed  
( barney@flowpoint.com )     stock 22R motor ; 3" body lift
Santa Cruz, Ca.              8" alloy rims; 31" BFG A/Ts
homepage: http://www.scruz.net/~barneym/barnhome.htm
______________________________________________________________

Mark wrote:

>Well, to continue the interrogation, I've been reading my Toyota repair
>manual. They direct me to replace the "silicon oil" in the coupling. I
>guess it either wears out (how does this happen?) or it seeps/leaks out
>(I don't see a seal in the diagrams). The manual does not break down the
>procedure on how to replace the fluid, but my local Toyota dealer says
>I'll need two tubes of the oil at $10/per to replace the old. Of course,
>they recommend complete coupling replacement for $100+.

I don't know what happens to the oil, but I would guess you are right 
about it leaking out over time. I played with fan clutches back when
I had a bad temp sender that drove me crazy - it was not the Toyota
part, and it seemed to read fine at normal temps, then shoot up to the
red when the engine was under stress. I tried a junk-yard fan clutch,
and the temp gauge response was the same. Then I bought a new 
(non-Toyota) fan clutch, still the same. I did not know the string
trick at the time, so had no idea how to check the clutch. I finally
put a real OEM temp sender in, and that fixed my temp gauge problems,
I never did have a real overheating problem, but my entire cooling 
system is in real good shape now. I still have the new fan clutch on the
truck, and an assortment of old ones in the garage.

I remember reading on the Land Cruiser list about somebody who changed
the oil in his fan clutch, and he claimed success. I never tried it
myself.
______________________________________________________________
Barney McNamara              JENNY - 83 Toyota Short Bed  
( barney@flowpoint.com )     stock 22R motor ; 3" body lift
Santa Cruz, Ca.              8" alloy rims; 31" BFG A/Ts
homepage: http://www.scruz.net/~barneym/barnhome.htm
______________________________________________________________

Mark,
I got interested in the fan clutch and did some testing last night.
I found that mine only tightens a small amount, and does seem to
loosen up when it first warms up. I could never feel any tightening
by hand when it warmed up (while engine not running.) I tried the
kite string trick, and found:

#1 - the engine turns clockwise while facing the rear, so I had to
 tie my string to the battery side of the engine compartment to keep 
 the loop around the fan on the top of the fan to keep it from falling
 off.

#2 - when the engine was really cold, after not running for 2 hours, the
 kite string could not hold the fan when cold. (It could have been the
 sharp blades cut the string.)

#3 - garden twine is too strong to ever break, or I did not get the 
 engine hot enough. I drove around and up hills with the fan stopped.
 I got the temp gauge above center, but not up to the mark below the
 red line, and the twine did not break.

#4 - I was successful in breaking kite string by looping the garden
 twine over the fan blade, and tying the twine to a piece of kite 
 string that was tied to a bracket. (Note that the twine tied to a
 loop of string did not break the loop, because the loop was doubled
 kite string.) Then I had to block the air flow to the radiator with
 a piece of cardboard and then climb the steep hill. This time the 
 single string did break, but only after the temp gauge got up to the
 line below the red mark, not at normal operating temps.

My conclusion is that the effect of the fan clutch only kicks in when 
the engine is overheating, and that the fan clutch is a very subtle 
tightening, not an obvious hard lock.

Barney

PS - let me know what you find

At 11:09 PM 6/3/98 -0700, you wrote:
>Barney, I actually have the two "heat" problems and the exhaust leak. My
>temp gauge yo-yos and finally settles and when it has settled it starts
>to run too hot going up hill. I think the second problem is the fan
>clutch and I hope to get it out soon, that seems pretty simple to do. The
>gauge and exhaust leaks are annoyances for now and like, you I'll fix
>them when I get the time and $s.
>
>Mark
>
----------------
To: barney@flowpoint.com, dgharris@hns.com, richard@spawar.navy.mil
Date: Wed, 3 Jun 1998 14:17:29 -0700
Subject: Re: Temperature warble
X-Juno-Line-Breaks: 0,2-13,26-27,30-32
From: markadrian@juno.com (Mark D Adrian)


On Thu, 28 May 1998 13:11:44 -0700 Barney McNamara 
writes:
>>"With the truck cold, tie a length of "kite string" to one of the fan 
>blades,
>>and the other end to some point in the engine compartment.  Then 
>start
>>the car.   The string should be able to hold the fan when the engine 
>is
>>cold, and a good fan will break the string with engine warm."  Was a 
>>good quick check for me.


Barney :
OK, I did a variation on your procedure. First, with the engine cold, the
fan rotation is very stiff and doesn't spin freely either way. Second, I
warm up the engine to normal op. temp. and can stop the fan with a strip
of cardboard quite easily, in fact, I can stop it and spin it backwards
before it regains its normal direction. Finally, when I stop the hot
engine the fan spins freely in either direction. So, if there were enough
air circulating in there while driving, the fan's "grip" (with a hot
engine) is so weak, it might stop spinning all together. In any case,
when the engine is warm/hot, the fan doesn't seem to be spinning fast
enough because the air flow/stream is weak. I conclude the clutch's grip
isn't enough to get the job done. This would explain the symptoms I'm
experiencing with margin overheating on an uphill grade in the heat. 
What do you think?

I also notice I have an exhaust leak cause of fumes I smell in the engine
compartment, yet another problem to fix. I feel a little lightheaded now
from the fumes.

Mark

_____________________________________________________________________


Return-Path: 
To: barney@flowpoint.com
Cc: richard@spawar.navy.mil, dgharris@hns.com
Date: Thu, 4 Jun 1998 08:59:20 -0700
Subject: Re: Fan Clutch Test
X-Juno-Line-Breaks: 0,2-9,35-37
From: markadrian@juno.com (Mark D Adrian)


On Thu, 04 Jun 1998 08:17:01 -0700 Barney McNamara 
writes:
>My conclusion is that the effect of the fan clutch only kicks in when 
>the engine is overheating, and that the fan clutch is a very subtle 
>tightening, not an obvious hard lock.
>
>Barney

Barney :
Humm, very interesting observations. My immediate reaction is shouldn't
the string break before the engine gets to the point of overheating? I
mean, ideally, once the temp gauge "anchors", the fan should kick in
whenever it needs to keep it there. So, unless your water pump is
broke or the radiator is clogged/blocked, the gauge should maintain its
position based on the ability of the fan to push air through. I'm still
inclined to break mine down and replace the oil. There is an o-ring seal
in the clutch assembly. If that's leaking, you need an entire new clutch,
I don't think the o-ring can be ordered separately.  I also notice my
symptoms match yours, especially item #3. When I went to AZ last week,
the temp gauge would only move up (perhaps three of four needle's widths)
when I was pulling a hill and the outside air temp was over 90. On the
way home, I pulled up a BIG hill, about 4,000' vertical gain, it was
about 68-degrees outside, with strong winds, and the temp. gauge stayed
anchored where it always does. The evidence is compelling that there's a
fan clutch issue. The water pump etc. are all working fine as that long 
uphill pull proved. I can't think what else would manifest these
symptoms. I am just about ready to break the clutch out this AM and will
keep you posted. Finally, this was the first trip in a long time where I
ran in to hot weather (over 90). So, the clutch problem was never an
issue because it never got hot enough to cause a problem. The problem
could have been around for some time without being "expressed". It took a
stressful situation to create the problem, but, it's one that should be
fixed. I could envision the clutch slipping so much that the fan might
never spin and that would surely cause overheating unless you were in
North Dakota mid winter.

Mark

_____________________________________________________________________

Mark,
I think what I have seen is that the fan clutch tightens very slowly
and probably adds to the air flow as required while the air flowing
over the engine is heating up. The amount of tightening required to
break the string is only found when the temp gets "pretty high". Since
my test is totally uncalibrated, and the effect of the cardboard I 
needed to get it hot enough to break the string also affected the
air flow which should be heating the fan, I think my test is highly
flawed. I think the fan will help increase air flow as it heats, what
I found is that you can't see an immediate lock - and a specific temp
where it kicks in. The strength of your string will have an impact
on whether you see it kick in at all. The normal air flow through the
radiator caused by vehicle motion is the primary cooling agent for the
water. The results of this test would probably be different in a hot
area on a hot day, when the engine might be stressed at low speeds or
idle with no motion-caused air flow.

What I saw while lugging up a steep hill last night in Santa Cruz with
the air temp at about 60F and the fan stopped leads me to believe that 
the fan is only active on a hot day in Arizona, and that normal 
motion-caused air flow and a clean cooling system will keep these trucks
running at low temps. The evidence I have of the engine never heating at 
all without a thermostat, even with clogged water pipes, leaky hoses and 
radiator, and an old worn-out water pump further strengthens my opinion.
Unless the water flow is stopped by the thermostat, the system will
never heat up, fan or not.

Which brings up the thought - could your problem be a sticky thermostat?

Barney
 

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To: barney@flowpoint.com
Date: Thu, 4 Jun 1998 10:23:23 -0700
Subject: Re: Fan Clutch Test
X-Juno-Line-Breaks: 1-2,5-6,15-17
From: markadrian@juno.com (Mark D Adrian)

Well, my thermostat is about two or three months old, a toyota factory
original. 

Anyway, I finally just got three of the bolts off the pulley, I need a
2nd 10mm wrench. I also had to take off a couple of belts. I'm using some
bike tools as these small bolts are difficult to get to.

Back to the diagnosis, my general conclusion was that the clutch's "grip"
loosened as the engine warmed. That oil must be pretty sensitive to temp
changes. That is, it should thicken (engage) when the engine heats, not
loosen like it appears to. I was able to stop the fan easily when the
engine was running and hot (I used a cardboard stick, there was little,
if any, resistance). I could even think that with enough air gushing the
wrong way, that could stop the fan's motion. So, I've got to get back to
that final bolt, then the clutch should just drop down. Huh, nothing ever
goes that simply, so I've found.

Mark

_____________________________________________________________________

To: barney@flowpoint.com
Cc: dgharris@hns.com, richard@spawar.navy.mil
Date: Thu, 4 Jun 1998 12:08:44 -0700
Subject: Re: Fan Clutch Test
X-Juno-Line-Breaks: 4-6
From: markadrian@juno.com (Mark D Adrian)

OK, after some struggling, the fan clutch is out. But, I need to get a
deep-bladed phillips driver. The brass screws they use are too soft and
my drivers now are ripping the grooves up. Why do they use brass screws? 
That's a soft metal. Some things are better done with nuts. Oh well! At
least the thing's out now.

Mark

_____________________________________________________________________

To: barney@flowpoint.com
Cc: richard@spawar.navy.mil, dgharris@hns.com
Date: Thu, 4 Jun 1998 13:26:38 -0700
Subject: Fan clutch "unplugged"
X-Juno-Line-Breaks: 10-12
From: markadrian@juno.com (Mark D Adrian)

OK, I have the clutch out and disassembled. The fluid, or what's left of
it, looks and feels like thick honey. I can see evidence of seeping
around the edges (lots of gooey dirt deposits) despite the tight-fitting
o-ring. I will go to the dealer this afternoon for some of the silicon
oil which looks a LOT like 10W/40. I can't see needing more than one tube
of the oil, unless more has leaked than I think. Right now, there's
barely more than a film covering the large internal gear-looking
mechanism. I had to buy a 2nd 10mm wrench to get the nuts off (and back
on) and also you'll need a large-nosed phillips to undo the four brass
screws. Actually, I had to use vice grips on one of the screws that  I
tore up and will need to replace.

Mark

_____________________________________________________________________

To: barney@flowpoint.com
Cc: richardcarey@juno.com, dguy@king.cts.com, kenolson@pacbell.net
Date: Sun, 7 Jun 1998 18:57:57 -0700
Subject: Re: Fan clutch "unplugged"
X-Juno-Line-Breaks: 0-1,3-4,7-8,11-12,14-16,28-32
From: markadrian@juno.com (Mark D Adrian)

OK, I just got everything back together and here are some observations :

1)I still need an exhaust gasket, wow, I can smell those fumes in the
engine compartment!

2)the engine takes a LOT longer to warm up than it used to and the "new"
idle temp. is at least one needle's width lower. Lots of air moving out
of the fan now.

3)I needed only one vile of silicon fluid and the chamber was low. I
didn't replace the o-ring since I couldn't readily find one, the old one
looked good enough.

4)try though I may, I could NOT stop the fan from spinning at warm/hot
idle like I did before using a cardboard strip.


Conclusion : the fluid clutch's chamber over the (12+) years had seeped
and was low. Adding/packing in new silicon fluid changed the symptoms and
has hopefully solved the overheating problem. I will only tell next run
through a hot desert. The clutch seems to have a much stronger grip now
and the engine will probably run cooler. I will take a road test
tomorrow. I spent less than $20 for parts and new tools to fix the
problem. I spent about five or six man hours on the labor, which,
included a learning curve of course. While I was in there, I could have
also changed the belts, but they were new anyway, and also, if needed,
then was an excellent time to get to the water pump. A lot learned, a lot
of money saved, I just hope the problem is solved and there are no
residual glitches.

OK, thanks for everyone's help and suggestions along the way.

Mark

-----------------------------------
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Date: Tue, 21 Jul 1998 09:11:17 -0700
From: markadrian@juno.com (Mark D Adrian)
Subject: Overheating, 22RE, 1986 4x

I thought I had solved this overheating problem by repacking the fan's
fluid clutch, but, I still seem to overheat. My temp gauge normally rides
below horizontal, but on a recent trip through the desert, it rode about
2/3 or 3/4 the way up the gauge, especially "pulling" even minor hills,
then it goes back to "normal" when the highway flattens out. The
overheating manifests when the outside air temps are over about
90-degrees and stays "rock solid" otherwise.  I rechecked the fan's
clutch and was unable to stop the fan in the field. So, my question(s)
are :

1) Could the Toyota water pump, with 60K miles, be a culprit?  The seep
hole is dry and I don't hear any noisy bearing noises. Are there any
diagnostic procedures to confirm it's OK?

2) The thermostat is new, but, would it create these symptoms if it was
bad?

3) Would a clogged or dirty radiator core cause this problem?

4) I don't think there are any other components in the cooling system
that would allow it to keep running as it is, are there?

5) With these symptoms, what would you suspect the problem is?

Thanks,
Mark

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