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Fan Clutch questions ?

11K views 30 replies 10 participants last post by  nwarp 
#1 · (Edited)
I just changed my heater core valve. heat is not blowing inside the cabin. I did the fan clutch test and it failed. I just looked at these fan clutches online. I don't get how a fan clutch can fail because it just looks like a plate that you tighten to the fan with screws. I replaced my Timing belt, water pump etc. So maybe I did not tighten the fan clutch properly? wouldn't that be more likely than a faulty peice of metal/???

If it was bad would it cause the heating problem?

well Im going to take off and reinstall the clutch and see what happens. I thought tightened it enough before.
 
#2 ·
How It Controls Speed
# The fluid inside the fan clutch thickens as it gets hotter. The plate attached to the engine is constantly spinning, causing the fluid to spin and turn the plate attached to the fan. When the fan clutch is cool, the thin fluid only pulls weakly on the plate attached to the fan, causing it to spin slowly and not use very much power. As the clutch heats up with the rest of the engine compartment, the fluid thickens. The thicker fluid acts like glue, pulling on the fan plate and making the fan spin almost as fast as the crankshaft. When the engine cools down again, the fluid thins and lets the fan slow down.

INTERESTING
 
#3 ·
snookay has given you a good description of how the viscous clutch works; note that the engine has to be pretty hot ie. idling in slow traffic for the viscous fan to start taking effect.

What exactly is your problem?
Do you have an overheating problem or are you concerned that your interior heater is not working?
 
#4 ·
there's no fluid in the fan clutch.. it acts exactly like a manual transmission clutch. It gets worn out and needs to be replaced. they are not self tightening. your fan clutch as no relation to your heat inside the car. all the fan clutch does is help cool your motor. if your fan clutch is bad and you keep running the car and/or driving it, you run the risk of blowing the head gasket. I have no idea what Bill is talking about. The only fan that would kick on if your motor is running too hot is the A/C fan. Acts as a secondary fan to help cool down the radiator.
 
#5 ·
Sorry Anstead but I think you are wrong.
I do not know about the car in question but I have owned a 1984 3231 and currently own a 1991 3181...both of which have a viscous fan attached to the motor via one of the drive belts.
This clutch has a silicon fluid inside, on the outside is a bi-metalic plate which heats up and bends at a certain pre-set temperature. This plate presses on a plunger which releases the fluid which flows into the clutch internals and stiffens up the assembly. When the motor is cool, you can easily spin the clutch by hand...when the motor is hot (and heat is transfered to the viscous clutch) the clutch gets stiff and is difficult to spin freely.

In addition to this viscous clutch, there is usually an additional electric fan in front of the aircon radiator which is activated by a two temperature sensor at the top of the radiator.This has a thermal sensor that activates the electric fan at low speed at 91 degrees centigrade and a second thermal contact that kicks in at 99 degrees Centigrade and powers the fan at high speed.
This may not apply to the particular vehicle mentioned but I believe the basic theory will apply to all E30 cars.
My question is still as follows: Is there a problem with overheating of the engine or is the problem with the flow of hot air inside the car...either way the problem could be an airlock in the cooling system that requires bleeding out.:dunno:
 
#9 ·
if youre not getting heat, its something else. if your temp gauge is getting hot at idle or low speeds, yes your clutch is bad.

now from what it sounds like, is you have air inside the heater core. i would try bleeding the cooling system a few times first. worst case scenerio is you have a clog and youd have to backflush the full cooling system
 
#10 ·
if youre not getting heat, its something else. if your temp gauge is getting hot at idle or low speeds, yes your clutch is bad.

now from what it sounds like, is you have air inside the heater core. i would try bleeding the cooling system a few times first. worst case scenerio is you have a clog and youd have to backflush the full cooling system
Cool thanks. Ill do it more. I only did it once and it seemed like only coolant was coming out. How many times do you folks normally findyourself bleeding the air out?
 
#13 · (Edited)
Well the over heating problem was clearly my fault... I'd rather not talk about it :cry:

The temp is staying at 50% now. I still am not getting any heat inside the car after bleeding the air for a while. Should I be 100% sure it's the heater core now? Now that I think about it I'm going to make sure I'm still getting power to the new heater core valve. I assume it's a pump that gets the fluid into the heater core right? Look at my old one. If im still getting power I guess I go ahead and get another core :mad:

@ Noexceptions. I already ordered a fan clutch yesterday. Since my car isnt overheating ill just install it whenever I have other stuff to do in that area. It was only $40.
 

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#14 ·
that looks like one rooted hcv lol. Your on the right track with checking the power to the heater control valve, i was thinking exactly the same as i was reading the sentences before. The coolant flowing through the heatercore is just another path for the coolant flow of the whole engine so its powered by the water pump, the heater control valve simply opens the pathway and allows the coolant to flow through the heater core.

Turn the ignition on, and move the heating dial from cold to hot back and forth, you should hear the heater control valve click, also if you put your hand on it you should feel it click too.

check you connected the heater hoses back on the right way around, dont ask me how i know lol, have a look at the pic in my thread from almost two years ago http://www.bimmerwerkz.com/forum/3-series-e21-e30/heater-core-68235.html,

If the heater control valve seems to be working fine its possible you have a blocked heater core. Your not going to like this but if you are sure you have bled the air out, pull the heater core out again and run the hose through it, run the hose through it both ways a few times, (direction of flow and backwash it) make sure the flow is easy, be carefull not to pressurize it though the garden hose pressure might be more than it can handle and burst it. Also if you take it out again have a play around with the heater control valve while its plugged in but not connected. With the ignition on and the heater valve plugged in set the temp to cold and pour a little water down the inlet tube of the heater valve, it should not come out the outlet, now turn the temp gauge to hot, the valve should open (you will hear it click) and the water should flow out the bottom
 
#15 · (Edited)
Let me add one more thing to the equation... I only can get < 1.5 gallons of coolant into the car before it starts coming out of the overflow exit. It was over heating because I only added 2 quarts, it began overflowing and i forgot to add more after i let it drain into the engine. I went to sleep last night and this fact hit me me out of no where. So then i put 1.5 gallons in and it begins to overflow with NO signs of allowing me to add any additional fluid. I ran the engine and i still can't add anymore. FYI haynes says this car takes 3 gallons of coolant.

Did someone stick a banana in my coolant pipe. Anyhone ever hear of something like this before?
 
#18 ·
@TIM I held the valve while switching on the car and i could not feel anything. I checked the fuse box which led to me plugging my radio fuse back in and heat came back into the cabin... WTF

the temperature is staying regulated now. there is heat in the cab now. The coolant light is off; which may or may not mean anything. I'm going to put the thought of taking the radiator out for another time months down the line. radiators don't explode right? lol

thanks you everyone for all the assistance.
 
#26 ·
I don't see how those fans would explode without you hitting something. I know you meant the blades, but it still doesn't make sense how it just decided to blow up. I'm not reading through all that crap. In an e30 if your fan blade hits your fender you're doing something terribly wrong...actually...you're missing a key point in the chassis of your car if it hits the fender.
 
#28 ·
I don't see how those fans would explode without you hitting something.
All I know is only from what I read.

I read all those threads and from what I remember, what people seem to think happens is the viscous fan clutch locks up.

See this description, for example.

That makes the fan spin at some direct multiple of the engine speed (depending on how the fan pulley diameter compares to the crankshaft pulley diameter).

See this description, for another example.

I'm not sure how long the fan has to super-spin before the blades shoot off; but there are plenty of pictures of the results ... so it must be happening.

The moral of the story is to replace the viscous fan clutch with every cooling system overhaul. You don't necessarily have to replace the fan blades though - unless you suspect the viscous fan clutch - in which case you'd be prudent to replace the entire assembly.

All I can tell you from personal experience is that, when my cooling system exploded, I replaced MY fan clutch (after buying the necessary fan clutch nut & waterpump bolt counterhold tools).

:)

 

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#29 ·
Maybe your fan clutches are different than ours.

The E39 fan clutch unit is viscous. We discussed it just this past December 28th over here (see also the fan troubleshooting PDF).

That means there is a fluid coupling and a thermo-sensor (bi-metallic strip).


When everything is cold, a rolled-up newspaper (or even your hand if you're brave) can prevent the fan from turning at engine idle.

But as it heats up, the fluid moves into passages inside the fan clutch causing the fan clutch to increasingly "lock up" such that the fan moves faster and faster (closer and closer to the speed of the rotating water pump).

I don't think whether or not the engine gets "hot", per se, is the issue (what I mean by that is that the engine temperature and the fan clutch temperature are two separated entities - they're related - but they're separated events).

Of course, many say that it's not the fan clutch failing that causes the fan blades to shear off ... they say (see here) that it's the motor mounts.

I only know what I read ... so I learn from other people's experience!
And, I do NOT want to experience what some people experience!

:)

 

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