Fan clutch replacement

[FGS]

Hi everyone,

my 1973 3.0 CSi has overheating issues when the engine is at idle or runs at very low speeds.

This happens with an outside temperature of 75F, let alone an higher temp.

The radiator has been rebuilt and the thermostat is a correct new one (80°) from WN.

The mechanic told me that the fan clutch is gone: mine is an early one with a five blade fan.

Questions:

Is there any chance I could find another clutch like mine (nope, WN doesn't have it)?

May I use a 9 blade fun/clutch assembly of a later E9?

What about removing the actual fan and install an electric one?

Thanks

 

[HB Chris]

The early friction style clutch is long gone. You can use the first version of the viscous clutch without changing your water pump, it has a mount that holds the new clutch. That allows you to use the later eight/nine blade fan for improved cooling.

 

[Thomas76]

This style water pump pulley allowed me to convert to the 9 blade if it helps.

New clutches are available.

 

[HB Chris]

Your pic is the second version water pump with the spin-on clutch that has a large 32mm nut.

 

[sfdon]

And never store a fan clutch on its side!

 

[FGS]

Thank you everyone.

I understood that a later 9 blade fan with its clutch can be installed bolt-on on my water pump.

However I looked for that fan and I found only the black one: any source for the red one?

Thank you.

 

[HB Chris]

Red is hard to find, black is pretty easy.

 

[stphers]

How much friction material is left on the clutch piece? Did you heat the center bulb up with a hot air gun and see how far the pin will protrude? Most of the time , the problem is that pin does not come out far enough to push on the clutch to make it tight on the fan coupler housing. If there is enough material on the clutch ( which it looks like there is plenty ) give it a light sand to get rid of the glazing on the material, sand the contact surface in the housing where the clutch engages Add a shim in the center hole of the clutch to make up for the bulb not coming out as much as it used to I keep old thin cutting discs that have worn down just for this Pretty much all the ones that I have added shims to have worked very well with engaging the fan as it gets hotter and going free running when cold Keeps the original set up and pretty cheap to do Young mechanics just don't know about this stuff

Thanks, Rick

 

[HB Chris]

That’s a great tip!

 

[bmw2800cs]

How much friction material is left on the clutch piece? Did you heat the center bulb up with a hot air gun and see how far the pin will protrude? Most of the time , the problem is that pin does not come out far enough to push on the clutch to make it tight on the fan coupler housing. If there is enough material on the clutch ( which it looks like there is plenty ) give it a light sand to get rid of the glazing on the material, sand the contact surface in the housing where the clutch engages Add a shim in the center hole of the clutch to make up for the bulb not coming out as much as it used to I keep old thin cutting discs that have worn down just for this Pretty much all the ones that I have added shims to have worked very well with engaging the fan as it gets hotter and going free running when cold Keeps the original set up and pretty cheap to do Young mechanics just don't know about this stuff

Thanks, Rick

Ok, I apologize in advance because I don't know what material the contact surface is made of but here goes ...
Wear an N95 when you sand that surface. If it isn't needed all of you know more than I do - just let me know, I'll shut up

 

[FGS]

How much friction material is left on the clutch piece? Did you heat the center bulb up with a hot air gun and see how far the pin will protrude? Most of the time , the problem is that pin does not come out far enough to push on the clutch to make it tight on the fan coupler housing. If there is enough material on the clutch ( which it looks like there is plenty ) give it a light sand to get rid of the glazing on the material, sand the contact surface in the housing where the clutch engages Add a shim in the center hole of the clutch to make up for the bulb not coming out as much as it used to I keep old thin cutting discs that have worn down just for this Pretty much all the ones that I have added shims to have worked very well with engaging the fan as it gets hotter and going free running when cold Keeps the original set up and pretty cheap to do Young mechanics just don't know about this stuff

Thanks, Rick

Thank you for the suggestions, however this is a quite complex topic and i don't get everything. For instance, do you have a schema related to the fan clutch parts?
I don't understand where the bulb is and what is its shape.
At least from the photos I made I'm not able to spot it.

Thank you.

p.s. Mechanic told be that he could make the fan "always on" by fixing the clutch but I'm terrified that some people working with the engine running might cut off a finger. Besides, I suppose that if BMW have designed the fan in this way there will surely be a reason other than security.

 

[stphers]

In your first post, in the second picture, the top part that looks like a wagon wheel, is the clutch part that has the clutch material on it ( around the edge ) The round bit in the second picture at the bottom is the bulb, on the frt side, it looks like a propeller, the bulb is on the other side It has a special compound in it that as it warms up ( engine getting hotter ) causes the bulb to expand and push on the fan clutch part to cause it to lock up against the housing that is bolted to the water pump The bulb extends into the clutch part, that is where you put a shim. Show this to your mechanic, he should be able to figure it out with this info. Why not try it, you have everything apart already

Yes, you can lock it up solid and think about it, when working on the engine, it will get hot, the fan clutch will engage and be locked up anyways so watching out for fingers is something that should be done anyways Not such a good idea to lock the fan as it may take a lot longer to get the engine up to operating temp with a locked up fan which is not good for a lot of reasons

Thanks, Rick

 

[Honolulu]

Paging SFDon: you advise never to store a fan clutch on its side and I've often read that (though no one ever explains why/not).

But how can we know whether fan clutches were stored properly before we buy them?

 

[FGS]

In your first post, in the second picture, the top part that looks like a wagon wheel, is the clutch part that has the clutch material on it ( around the edge ) The round bit in the second picture at the bottom is the bulb, on the frt side, it looks like a propeller, the bulb is on the other side It has a special compound in it that as it warms up ( engine getting hotter ) causes the bulb to expand and push on the fan clutch part to cause it to lock up against the housing that is bolted to the water pump The bulb extends into the clutch part, that is where you put a shim. Show this to your mechanic, he should be able to figure it out with this info. Why not try it, you have everything apart already

Yes, you can lock it up solid and think about it, when working on the engine, it will get hot, the fan clutch will engage and be locked up anyways so watching out for fingers is something that should be done anyways Not such a good idea to lock the fan as it may take a lot longer to get the engine up to operating temp with a locked up fan which is not good for a lot of reasons

Thanks, Rick

Understood.

Thank you very much!

 

[sfdon]

“But how can we know whether fan clutches were stored properly before we buy them?”


oh that’s easy.

they won’t work!

I follow instructions on latest boxes- not the old service bulletin



The SACHS fan clutch assists the engine to maintain its correct operating temperature. When the engine temperature exceeds a certain level, the fan clutch is activated causing additional air flow through the radiator. The fan clutch is activated when hot air passes over a bi-metal strip 1 on the fan clutch, causing deformation of the bi-metal strip which activates the control pin 2.

The control pin opens the valve 3 allowing silicone oil 4 to enter the drive chamber of the fan clutch. The temperature controls the speed of the fan clutch i. e. higher temperature causes higher speed. As temperature decreases, so does the speed of the fan clutch.

Transport and Storage
To ensure proper function of the fan clutch we recommend that these instructions be followed. It is most important that the fan clutch be
positioned correctly during transportation and storage. Please note the arrow on the fan clutch package. The fan clutch should be
stored either vertically but preferably flat with the arrow pointing up. This is to ensure that silicone oil does not leak past the control pin seal. Should a small amount of oil leak past the control pin seal due to incorrect storage, the fan clutch will still perform correctly.

 

[Candia4441]

Hi everyone,

my 1973 3.0 CSi has overheating issues when the engine is at idle or runs at very low speeds.

This happens with an outside temperature of 75F, let alone an higher temp.

The radiator has been rebuilt and the thermostat is a correct new one (80°) from WN.

The mechanic told me that the fan clutch is gone: mine is an early one with a five blade fan.

Questions:

Is there any chance I could find another clutch like mine (nope, WN doesn't have it)?

May I use a 9 blade fun/clutch assembly of a later E9?

What about removing the actual fan and install an electric one?

Thanks

I think this is just a question, why cant we remove fan and fan clutch and install a electric fan that I am planning to do on my car like a new BMW and it will add a 20 to 30 HP on engine and will run much more smoother and less engine noise am I right?

 

[stphers]

You can but when a fan clutch is working properly, it is only engaged usually at idle or when the car is sitting for any length of time running. When driving, there should be enough airflow over the rad to keep the engine at a good operating temp and the fan clutch from engaging so when the fan is free wheeling HP drop is nothing any of us would ever notice and I think your HP is not really a gain, just using what is already there and 20-30 HP is pretty big estimate 10-15 is more realistic

 

[sfdon]

you are spot on!
And add an electric turbocharger and you could see horsepower gains of up to 100 horsepower!

 

[sfdon]

But wait-there’s more!!
do it right and add the dump valve simulator!

 

[Gazz]

you are spot on!
And add an electric turbocharger and you could see horsepower gains of up to 100 horsepower!

You know you can set them up in series so that each turbo boosts the next in line for exponential increases in HP. PLUS, you can add the fake dump valves in series with the turbos and with a rising chromatic scale sound, ( or tune of your choice ), as each stage engages. BRILLIANT!

Note - customers will be required to work out how to assemble this themselves. ( NOT comes with anything to make it work ).