Terrible screeching noise, clutch fan? +vid

[nismoskyz]

::Hatch S13
::KA24DE

Recently, out of nowhere, my car started making this terrible screeching sound that comes in right at about 2850 RPM and only gets worse as the RPMs increase. The sound stays at a steady loud volume from about 3500RPM on up.

It seems to only come when the clutch fan is on, and the noise actually disappeared for about a week, then just came in again this Friday.
Now, normally the clutch fan isn't on all the time, but since Friday, everytime I drive the car, it hasn't gone off for a moment. (driven in ambient temps from 50 degrees to 90 degrees, fan still on)

*What causes the clutch fan to turn on in the first place?
*Why isnt it turning off?
*How can I fix that noise? .. is there any spray or something to possibly lube something up, or is it some belt that has worn out?

video:YouTube - KA screach noise (http://www.youtube.com/watch?v=mvJWLx5Kfv0)
*updated link

I'd really appreciate some help here
thanks


**SOLVED**
The problem has been fixed by replacing my fan clutch, which I believe was seizing up and causing the belts to slip.

[Razi]

Sounds like a belt that's slipping.

[ryguy]

Sounds like a belt that's slipping.

I agree. Probably your water pump belt. I bet it started once it started getting colder out.

[nismoskyz]

Well it only seems to happen when the clutch fan kicks in though.. and the clutch fan hasn't stopped at all for a few days now every time i drive..

weather here fluctuates alot though.. we'll have 65 degrees one day and 95 the next.. lol, we don't get real 'seasons' .. climate seems to change by the week :P

[Razi]

Maybe that extra load from the clutch fan is making it slip, not sure.

Check your belts sometime, see if they look worn.

[JayDee M Rolly]

sounds like a clutchfan, mine made that exact sound

[ryguy]

Maybe that extra load from the clutch fan is making it slip, not sure.

Check your belts sometime, see if they look worn.

That's what I was thinking. I don't run a fan, so I don't know how often the clutch fan is supposed to be engaged, but I do know a slipping belt makes a horrible, LOUD squealing noise.

[nismoskyz]

you're right it was...

i went to some mech shop yesterday and the guy pointed out to me how difficult the fan was to turn by hand and was charging around $120 to replace it.

i went home and vacuumed the fan clutch area while tapping the area with a tool to shake some more dust off and a lot of it came out.
got some PB Blaster and just kept spraying it in the center area of the fan clutch, though the opening was tiny and i kept rotating the fan left and right trying to free it up.

eventually it became smooth as butter. i started up the car and sure enough, the fan finally didnt stay on loud-mode, and revved up to 3K+ and no squeak! http://www.240sxforums.com/forums/images/smilies/biggrin.gif
however, i drove the car last night and just after i got off the fwy, it seems the bearings might have locked up again and the fan turned on again and the belt squeak noise came back.

i got some "white lithium grease" spray from autozone and sprayed that stuff in last night and once again got the fan to spin very smoothly. drove the car again and So far, still spinning smoothly. http://www.240sxforums.com/forums/images/smilies/smile.gif

i do have a bunch of freeplay in the fan clutch though.. i'm sure it's going to need replacing, but at least i have a temporary fix.


So about that belt noise.. im thinking that maybe since the fan was being forced to stay on, after the fan got to it's max speed, as the engine speed continued rising (around 3K RPM is where the screeching sound came in), maybe the fan was forcing some belts to spin slower than the engine and therefore caused them to slip??

thanks a lot for all your suggestions
-nismoskyz

sounds like a clutchfan, mine made that exact sound

[aznpoopy]

what the hell

the fan clutch is a viscous sealed unit. it has fluid inside that locks up as it gets hotter, locking the fan. yes, when the fan clutch goes it seizes. as you figured out, the belt slips when the locked fan gets up to speed.

you shouldn't be spraying anything into it to get it to 'free up.'
all you need to do is get another clutch unit and replace it.
it takes maybe thirty minutes to get it done and the unit is cheap. maybe 50 bucks from autozone.

[nismoskyz]

well i dont really know how far in the spray penetrated, but i sprayed it into the center of the fan clutch and it worked by making the fan spin smoothly again.. but idk how long it will last.

you're right though i am in need of another fan clutch.. there should be some good used ones floating around i hope.. autozone charging $50 - $90

..or maybe the spray i put in there did nothing and the only reason it became smooth was because i kept rotating the fan left and right? it really feels much smoother now though.. the spray had to do something.

[adam bergener]

or you could go to the junk yard and get a E fan for around that i got a honda fan lol just wired to a switch

[CrazyKoukiS14]

belt slipping

[S-Nation S13]

Belt slippin change out powersteerin and alt youll be fine if you change one change the other saves you the hassel if the one you didnt change slips like a day after you change the previous one.. done!!

[nismoskyz]

Actually, I have since replaced the fan clutch with another (better) used one and the noise has disappeared entirely.

I didn't have to touch any of the belts :)

I believe that my old fan clutch was seizing up and messing up the belt speeds causing them to slip.

thanks

[reinvent]

Actually, I have since replaced the fan clutch with another (better) used one and the noise has disappeared entirely.

I didn't have to touch any of the belts :)

I believe that my old fan clutch was seizing up and messing up the belt speeds causing them to slip.

thanks

I dont think there is anything wrong with your original fan clutch. They start off very stiff until the oil warms up from the fan rotating. They are on all the time as far as I know. If you drive around for awhile, your fan has more free spin. (when engine turned off). The fan clutch has a bimetal strip on the front which causes the fan to get tighter as temperature goes up but i think this only happens when hood down and temperature quite high.

Is your new fan clutch as stiff as the old when you car is completely cold?

your belt or pulley is glazed , likely. or belt was loose.

other people i have talked to say that new fan clutches are stiff when new. ie they only spin about a third of the way around

[Felipe]

i say it squeels again later on.... just because i say its one of the belts.

[ryguy]

I dont think there is anything wrong with your original fan clutch. They start off very stiff until the oil warms up from the fan rotating. They are on all the time as far as I know. If you drive around for awhile, your fan has more free spin. (when engine turned off). The fan clutch has a bimetal strip on the front which causes the fan to get tighter as temperature goes up but i think this only happens when hood down and temperature quite high.

The fan clutch is more loose when it's cold, and gets tighter as the vehicle heats up. The inside is filled with hydraulic oil that expands when it heats, pushing the clutch together. It should still have good resistance when it's cold, if not there's likely no hydraulic oil in the clutch anymore. That's wierd that changing the fan clutch made the noise go away.

[reinvent]

The fan clutch is more loose when it's cold, and gets tighter as the vehicle heats up. The inside is filled with hydraulic oil that expands when it heats, pushing the clutch together. It should still have good resistance when it's cold, if not there's likely no hydraulic oil in the clutch anymore. That's wierd that changing the fan clutch made the noise go away.

there is a thermostatic spring on the stock clutches:

The fan clutch operation is regulated by a valve that is opened and closed by a thermostatic spring. The valve controls the flow of a viscous silicone fluid between chambers in the clutch assembly. When the engine is cold, the clutch is essentially disengaged, which is why the fan runs at its slowest compared to the engine's speed. As the engine warms up, the air flowing to the fan assembly becomes hotter. The hotter air causes the thermostatic spring to unwind and open the valve. Silicone fluid from the reservoir chamber flows into the main chamber, engaging the clutch, and the fan spins faster (though it's still slightly slower than the engine).

[reinvent]

OP, you better fire your mechanic. Thermal clutches like ours are supposed to be locked up when the engine is off or cold. the squeal has gone away because you have changed the alignment of belt when replacing clutch.

A thermal fan clutch is engaged on a cold startup because the fluid drains into the working area when the engine is shut off.

Thermal Fan Clutch


Varies the fan speed with temperature of the air behind the radiator.
Engaged (high speed) operation provides maximum cooling.
Disengaged (low speed) operation provides fuel savings and noise reduction.
Greater life expectancy than a non-thermal clutch.
Briefly engaged at cold start-up.
Engages at about 170° radiator air temperature, (about 30° lower than coolant temperature).
The air temperature coming through the radiator is sensed by the bi-metal thermal spring on the front of the thermal fan clutch. It expands and contracts with the change in air temperature operating a valve inside of the clutch. When cold, the silicone drive fluid is pumped from the working area to the reservoir. When hot, the valve opens allowing fluid from the reservoir to be transferred to the working area thereby increasing the fan speed. The clutch disengages as the air temperature decreases, closing the valve and allowing the silicone fluid to be pumped back into the reservoir.
A thermal fan clutch is engaged on a cold startup because the fluid drains into the working area when the engine is shut off. The fan clutch will slow down shortly after startup as a result of a pumping action produced by a difference in speed between the shaft and the body of the clutch.
Most models are designed to duplicate original equipment performance. Some Chevrolet/GMC truck models are specifically designed to engage at lower temperatures than the original equipment parts that they replace.

[reinvent]

the bimetal element that controls the valve as temp changes is circled in red.

[nismoskyz]

Those are some very informative posts.

I still believe it was my old fan clutch that was causing the belt slipping because the old fan clutch was extremely difficult to turn by hand. I had to put a lot of force just to make it move left and right and on top of that, when it was installed, the fan blades had a lot of free play in the center of the fan clutch where blades attach.

Whereas, the new(used) fan clutch that I obtained, since installed, spins very smoothly and has no free play if i move the blade around.

*(by free play, (when standing in front of the car) i dont mean rotating left and right, i mean forward and backward movement)

I am no expert on fan clutches, however my theory is that my old fan clutch was seized up inside and was locking, staying on all the time, and couldn't keep up with engine speed after 2800 or so RPM and so, caused the belt to slip.

[kouki_matt]

stop being cheap asses and go get a new one i got one at autozone and three months later it locked by a good one from nissan and do it once pm me if you think im wrong

[nismoskyz]

dude, use some punctuation.

btw, i got a used oem fan clutch (for free) and its been working great.

[S14Cuhh]

on my car i ahd a ps fluid leak running on the belt. thats what made my squeal. but once the car was warm it didnt anymore

[bmar240sx]

You have a loose wire that at any time move and get eaten by the clutch fan i suggest you fix that

[nismoskyz]

I think I remember that wire being pretty tight in its position, but I'll definitely take another look at it just to make sure. Thanks for the tip.

[CrazyKoukiS14]

cfan or belt