Viscous clutch question

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ES 1800

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I had to change the water pump on my '73 3.0CS. It appears the viscous clutch is not working correctly. When I tighten the center bolt of the fan, the fan will not spin. I.e, i believe the clutch is frozen.

I'm a Volvo guy with one BMW. On the Volvo, the viscous clutch is in part of the finned hub that the fan bolts to with 4 small bolts. From reading the BMW service manual it appears that the BMW clutch mechanism is behind that, and that is the unit that needs replacing. Is that the case?

I see what I think I need listed for the 1974 and 75 models, but not the 1973. Where might I find one for the 73?

The picture below is what I believe is NOT the viscous clutch. Am I correct?

BMW fan.jpg
 
E4318C2B-34BF-4C08-B0BD-996E5E264F86.png

Yeah- that’s the fan clutch.
 
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The e9 never had a viscous clutch, it was a friction clutch. Sounds like you have a water pump and viscous clutch that mounts to a post with a center bolt to hold the clutch. The other version uses a newer pump with a large 32mm nut known as a spin-on clutch.
 
I mounted this one to my car if it helps, I've got the 8 blade red fan and the water pump with a center bolt.
IMG_20200717_175404756.jpg
 
HB Chris said:
The e9 never had a viscous clutch, it was a friction clutch. Sounds like you have a water pump and viscous clutch that mounts to a post with a center bolt to hold the clutch. The other version uses a newer pump with a large 32mm nut known as a spin-on clutch.
Click to expand...
I have the 2-volume BMW service manual binders that says 2500-3.0CSi on the cover. Here's a picture of the page I was looking at.That's why I asked about 'viscous clutch.' Maybe I should have said viscous coupling but as you see the top picture in the service manual does not look like what I have. the 3red one down does.
BMW Servic Manual.jpg


This is a picture of my fan.

BMW red fan.jpg
 
I was mistaken, the 74 got the viscous clutch instead of the friction clutch. You need the one pictured that you also have, no large nut in the backside of the opening, it works with the early pumps. And yes, they are very expensive, get the one Don recommends.
 
ES 1800 said:
I had to change the water pump on my '73 3.0CS. It appears the viscous clutch is not working correctly. When I tighten the center bolt of the fan, the fan will not spin. I.e, i believe the clutch is frozen.

I'm a Volvo guy with one BMW. On the Volvo, the viscous clutch is in part of the finned hub that the fan bolts to with 4 small bolts. From reading the BMW service manual it appears that the BMW clutch mechanism is behind that, and that is the unit that needs replacing. Is that the case?

I see what I think I need listed for the 1974 and 75 models, but not the 1973. Where might I find one for the 73?

The picture below is what I believe is NOT the viscous clutch. Am I correct?

View attachment 107118
Click to expand...



i have a couple of photos that might help

here is the adapter to the earlier pulley, and the central bolt
A1B3727A-00E9-4A8F-9070-782777A1F6A6.jpeg


and here the fan with viscous clutch in the center
CA962947-9ED6-4E0A-926D-81DDA406C658.jpeg



why do you say your clutch does not work ?
 
ES 1800 said:
As I look at the eBay listing it does not show it to be compatible with a 1973 3.0CS. Lists 1975-79. You say you have a motor out of a Bavaria, I know the Bavaria was an E3, but was said to have everything under the skin the same as the E9.
Click to expand...
I think I compared pictures on Ebay to what I had in front of me then rolled the dice and it turned out fine.
With a 50 year old car it seems you never know what ya got, I chose to trust pictures more than descriptions.
 
deQuincey said:
i have a couple of photos that might help

here is the adapter to the earlier pulley, and the central bolt
View attachment 107137

and here the fan with viscous clutch in the center
View attachment 107138


why do you say your clutch does not work ?
Click to expand...
Thank you for the pictures and reply. The reason I say I believe it does not work is that the BMW Service Manual says that when the motor if off the fan should spin freely. It does not. (Yes, I can move it but the alternator and power steering pulleys move too. I seem to recall several years I could give it a whirl by hand and it would spin.)

Your top photo looks like what I have, the bottom does not. Your bottom one has a plate over the finned portion and mine does not.My fan is red, yours is not.
 
ES 1800 said:
Thank you for the pictures and reply. The reason I say I believe it does not work is that the BMW Service Manual says that when the motor if off the fan should spin freely. It does not. (Yes, I can move it but the alternator and power steering pulleys move too. I seem to recall several years I could give it a whirl by hand and it would spin.)

Your top photo looks like what I have, the bottom does not. Your bottom one has a plate over the finned portion and mine does not.My fan is red, yours is not.
Click to expand...

SEAT back and relax

Your fan would spin freely with a friction clutch but not with this

Visco keeps always some strength

The way to check failure for visco involves an stroboscopic lamp

Yours is the same thing mine is black that is all, you do not love black ?

The plate in front of finned part is rear side, my front side has no plate

Your clutch is probably ok

If you have doubts look at the blue books for instructions

Cheers
 
deQuincey said:
SEAT back and relax

Your fan would spin freely with a friction clutch but not with this

Visco keeps always some strength

The way to check failure for visco involves an stroboscopic lamp

Yours is the same thing mine is black that is all, you do not love black ?

The plate in front of finned part is rear side, my front side has no plate

Your clutch is probably ok

If you have doubts look at the blue books for instructions

Cheers
Click to expand...
I hate to take issue with someone with as many messages as you have and such a high score, but I am really confused by all of this. Some people say I have a viscous clutch (and so does the BMW Service Manual, apparently) while others say I have friction clutch.

I have the radiator out, I know I could run the motor for a short period without coolant but I am guessing whatever coolant is in the block is gonna come flying out all over creation. (I can find no place to drain the block, either.)

Here is what I see in the blue books (the BMW Service Manual for 2500-3.0CSi). I have underlined why I think my clutch fan is not working.
Fan check.jpg
 
ES 1800 said:
As I look at the eBay listing it does not show it to be compatible with a 1973 3.0CS. Lists 1975-79. You say you have a motor out of a Bavaria, I know the Bavaria was an E3, but was said to have everything under the skin the same as the E9.
Click to expand...
Thomas, I sent a question to the eBay supplier. He said, "This will not work .... You can look at uropartsDOTcom to see if they show what you need. " But if you tell me you have the same E9 engine as I do and it works, I am inclined to give it a try.
 
Jim, Your 73 originally had a friction clutch. It has been updated with 74 and on viscous clutch, you have the post which bolts to the pump with four bolts and the large center bolt which mounts the clutch to the post. Don‘s post shows the correct clutch. Your photo of your red fan matched Don and the third pic from the blue book you posted also matched. You can’t search for a 73 clutch, you don’t have that type anymore. It goes with the exact same water pump as well.
 
HB Chris said:
Jim, Your 73 originally had a friction clutch. It has been updated with 74 and on viscous clutch, you have the post which bolts to the pump with four bolts and the large center bolt which mounts the clutch to the post. Don‘s post shows the correct clutch. Your photo of your red fan matched Don and the third pic from the blue book you posted also matched. You can’t search for a 73 clutch, you don’t have that type anymore. It goes with the exact same water pump as well.
Click to expand...
NOW I GET IT! It would appear then the units form uroparts.com for $71 should work! It never dawned on me that someone had changed things.
 
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