Fan Clutch

[Justin]

Is there a set rpm the stock fan clutch is supposed to disengage? I've been noticing that it'll stay locked all through the power band, at idle, almost constantly... then randomly it'll release.

I just got a new muffler that made my car really quiet... you can't hear the muffler if the fan is locked, just the fan. its fucking annoying and I hate it.


Is itj ust supposed to be like this? I never remember that happening on any of my friends supras or anything like that....

 

[Bishop92t]

It's temperature based, not RPM based. If your clutch is old it may start to lock up more then it should, or it could slip more then it should. If your clutch is new then it's probably working as intended. I've noticed mine will lock and move a lot of air through the RPM band on a hot day if I'm sitting in traffic. Brand new unit. It's just that most Supra's clutch fans are worn out and slip too much, most people aren't used to how they really are supposed to work.

 

[Justin]

It's temperature based, not RPM based. If your clutch is old it may start to lock up more then it should, or it could slip more then it should. If your clutch is new then it's probably working as intended. I've noticed mine will lock and move a lot of air through the RPM band on a hot day if I'm sitting in traffic. Brand new unit. It's just that most Supra's clutch fans are worn out and slip too much, most people aren't used to how they really are supposed to work.

its fairly new, that's why I was suprised its making so much noise! Its horrible.. Anywhere, any gear, all you hears is the fan.


THanks for the reply man.

 

[supra90turbo]

gah... I hate that noise... it sounds like a tractor trailer "whooooooooooo"

 

[Justin]

gah... I hate that noise... it sounds like a tractor trailer "whooooooooooo"

I KNOW! You can't even hear my damn exhaust the fans' so loud!

 

[supraman7mgte]

thats part of the reason i went to elc fans got rid of whoooooooooooo
now its just whirrrrrrrrrrrr

 

[Bishop92t]

It should only make that sound when it's very warm. Before the car has warmed up it shouldn't unless there's a problem. It'll become less obnoxious after a year or two. Personally, I'd rather sound like a 18 wheeler then run the car too hot.

 

[DyslexicSquirrel]

It should only make that sound when it's very warm. Before the car has warmed up it shouldn't unless there's a problem. It'll become less obnoxious after a year or two. Personally, I'd rather sound like a 18 wheeler then run the car too hot.

true that...

 

[DaSuprawolf]

yeah my fan locked and i could really feal the drag, it was horrable. so i trashed it and elec. fans FTW!! no problems.

 

[mrnickleye]

Its Electric ! My fans, not the song & line dance !

Manual overides, 106* summer days, A/C always on. 180* thermostat. I'm Kool !

 

[toml]

My fan is the same - its SO loud.

Can anyone tell me how the fan clutch knows to engage? does it just have a liquid inside of it that locks up when it reaches a certain temperature? Is it common that they will lock up more often than they should when they get old, and is there a way I can test that it's working correctly?

We're talking about what Toyota calls a "fluid coupling", right?


EDIT: Wikipedia tells me that it is an electrorheological clutch (http://en.wikipedia.org/wiki/Electrorheological_clutch), but that seems to imply that it needs a voltage to lock up. The fan clutch on a Supra doesn't have any means of receiving a voltage, does it?

EDIT2: Howstuffworks.com clarified: "The fluid in the clutch gets thicker as it heats up, causing the fan to spin faster to catch up with the engine rotation. When the car is cold, the fluid in the clutch remains cold and the fan spins slowly, allowing the engine to quickly warm up to its proper operating temperature."

 

[Allan_MA70]

you going to get a hi stall moit!???

hehhehe

 

[SupraDread]

Is there a set rpm the stock fan clutch is supposed to disengage? I've been noticing that it'll stay locked all through the power band, at idle, almost constantly... then randomly it'll release.

Is itj ust supposed to be like this? I never remember that happening on any of my friends supras or anything like that....

Get used to it. I havent heard a quiet clutch fan yet. No need for alarm it just comes with the package. My 740 Turbo Volvo sounds the same as my Turbo MKIII one day I will get some electric fans yeah:icon_bigg more power, better gas mileage and stealthier motor. No more damm is my motor constipated sounds.

 

[Boostedstr8six]

My fan is the same - its SO loud.

Can anyone tell me how the fan clutch knows to engage? does it just have a liquid inside of it that locks up when it reaches a certain temperature? Is it common that they will lock up more often than they should when they get old, and is there a way I can test that it's working correctly?

We're talking about what Toyota calls a "fluid coupling", right?


EDIT: Wikipedia tells me that it is an electrorheological clutch (http://en.wikipedia.org/wiki/Electrorheological_clutch), but that seems to imply that it needs a voltage to lock up. The fan clutch on a Supra doesn't have any means of receiving a voltage, does it?

EDIT2: Howstuffworks.com clarified: "The fluid in the clutch gets thicker as it heats up, causing the fan to spin faster to catch up with the engine rotation. When the car is cold, the fluid in the clutch remains cold and the fan spins slowly, allowing the engine to quickly warm up to its proper operating temperature."

"Most fan clutches are viscous or "fluid" couplings combined with a bi-metallic sensory system similar to that in a thermostat."

There is a bi-met spring on the front of the clutch assembly that reacts to changes in temperature and rotates a small shaft which controls engagement/disengagement.

 

[toml]

Heh, cool... well after thinking about it last night, when I got up this morning and started my car I was more aware of the fan's behaviour... it started full speed when the car was still rock cold. Surely that's not right.

 

[Boostedstr8six]

Heh, cool... well after thinking about it last night, when I got up this morning and started my car I was more aware of the fan's behaviour... it started full speed when the car was still rock cold. Surely that's not right.

The fluid (probably some kind of oil/wax mix) is very viscuos when cold and the fan runs at full speed. When the fluid reaches operating temp it becomes less viscuos (kind of 'melts') and the bi-met spring mechanism (governed by temp) controls the amount of rotational energy that is transferred to the fan. At normal operating temp it's 'disengaged'. When the temp rises, the spring reacts rotating the control shaft and engaging the clutch mechanism resulting in higher fan speed/more air flow through the rad. When the temp of the air hitting the spring drops it reacts toward disengagement. HTH

BTW, I suck at explaining things....

 

[3p141592654]

So much misinformation... it is Silicone oil and the clutch lockup is controlled by a bimetal coil spring in the front (clearly visible if you take the clutch out). The coil when hot rotates a plate inside the clutch that exposes a series of holes around the periphery of the clutch allowing the silicone oil to drain out of its internal reservoir and fill the spacing between the two rotating clutch pieces causing them to lockup.

If the coil is damaged or the shaft corroded the clutch can stay in the locked or unlocked position all the time. If the oil leaks out, the clutch will not lockup, or will weakly lockup and the car will overheat.

If there is too much oil in the clutch, it will stay locked up all the time (I had this problem recently after a rebuild). The silicone oil can be bought from Toyota. You need 3 tubes.

Here is a link to a site that explains how to rebuild the clutch.
http://www.off-road.com/~estegall/tech/fanclutch/fanclutch.html

By the way, it is normal for the clutch to lockup for about 15 seconds after a cold start. The silicone oil drains out of the reservoir when stationary and you need the rotation to pump it back inside.

 

[89Turbo]

brought back from the dead yes i know but i thought it would be better than starting a new one. I just installed my fan clutch and am annoyed by the loudness of it but will survive until its time for electrics, my only question is that now from 2500rpm on up the belt squeals, its a almost new belt and never did before the new fan clutch.......also should the fan be fairly freespinning if i push the blade while the car is off? i actaully have to apply a bit of pressure to get it going........

 

[johnathan1]

Is it a new clutch? Or did you put new fluid in your old one?

 

[3p141592654]

If the fan is roaring constantly and the engine is cold, then you have a problem. Most likely too much oil in the clutch if you repaired it yourself.

When you start the engine cold you should clearly hear the fan roaring with a fast idle, then after maybe 15-30 seconds the noise dies away completely. If its not doing that, then drain some oil and try again.