Author Topic: 6.9 Simple Fan Clutch Check  (Read 445 times)

john erbe

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6.9 Simple Fan Clutch Check
« on: 14 June 2020, 06:29 PM »
Just to confirm, when engine is stone cold, you should not be able to spin the fan, correct?

daantjie

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Re: 6.9 Simple Fan Clutch Check
« Reply #1 on: 14 June 2020, 09:24 PM »
I went out to check mine and have long suspected it's long past due for a change.  I can spin it by hand for about one rotation when cold, depending on how hard I spin it of course.  I guess it is the original so must be long overdue, oh well let's add it to "the list" 8)  Mahle and Behr/Hella seem to be the go to ones?
Daniel
1977 450 SEL 6.9 - Astralsilber

TJ 450

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Re: 6.9 Simple Fan Clutch Check
« Reply #2 on: 15 June 2020, 04:35 AM »
You should be able to turn it but it shouldn’t freewheel. When you start the engine it should engage soon after starting for a short period of time then it will cut out again.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

daantjie

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Re: 6.9 Simple Fan Clutch Check
« Reply #3 on: 15 June 2020, 07:25 AM »
Yup mine keeps spinning pretty steady even with stone cold engine after start up so I'm sure it's done for ::)
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

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Re: 6.9 Simple Fan Clutch Check
« Reply #4 on: 15 June 2020, 09:02 AM »
Just to confirm, when engine is stone cold, you should not be able to spin the fan, correct?
I recently replaced mine.  The new one is surprisingly stiff.  You can turn it by hand but there's significant resistance and it doesn't spin at all.
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

john erbe

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Re: 6.9 Simple Fan Clutch Check
« Reply #5 on: 15 June 2020, 12:54 PM »
Ask because had one installed recently purchased from the Classic Center. Couldn't help but notice the high whirl that never cut out consistent with rpm. Day after pick-up, when engine cold did check, could not rotate fan however, when driving still had the constant whirl. Yesterday, on return drive whirl was now gone and everything back to normal running sound. Checked this morning and could easily rotate fan only slight resistance but could not spin. Just did test drive and can hear clutch working when hit accelerator. Plan to wait for hotter day temp and redo test drive.

UTn_boy

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Re: 6.9 Simple Fan Clutch Check
« Reply #6 on: 15 June 2020, 02:21 PM »
Ask because had one installed recently purchased from the Classic Center. Couldn't help but notice the high whirl that never cut out consistent with rpm. Day after pick-up, when engine cold did check, could not rotate fan however, when driving still had the constant whirl. Yesterday, on return drive whirl was now gone and everything back to normal running sound. Checked this morning and could easily rotate fan only slight resistance but could not spin. Just did test drive and can hear clutch working when hit accelerator. Plan to wait for hotter day temp and redo test drive.

If it was so stuck that it wouldn't initially turn then I'd recommend getting an exchange unit.  I understand that it's turning now, but Something is just not right, and I'd hate for it to come apart at speed and chew your radiator up.  (That's happened to me and many others before).  Brand new from the Classic center hasn't much bearing. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

daantjie

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Re: 6.9 Simple Fan Clutch Check
« Reply #7 on: 15 June 2020, 03:29 PM »
I did some googling and seems like one "good" test is with fully warmed up motor, from idle you should see and hear the fan ramp up in relationship to the revs until about 3000 rpm whereafter it will taper off relatively speaking as you rev up the motor beyond this range.   Then too if you shut off the motor the fan should stop pretty much immediately, if it free spins after shut down it's shot for sure apparently.
« Last Edit: 15 June 2020, 03:43 PM by daantjie »
Daniel
1977 450 SEL 6.9 - Astralsilber

john erbe

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Re: 6.9 Simple Fan Clutch Check
« Reply #8 on: 16 June 2020, 07:36 AM »
Update: Contacted Classic Center and asked if they would replace the fan clutch if found faulty. Their response "...100 200 00 22 80 Fan clutch no longer available. Kind regards/ Mit freundichen GruBen"

daantjie

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Re: 6.9 Simple Fan Clutch Check
« Reply #9 on: 16 June 2020, 08:13 AM »
Is part # not 116 200 05 22?
Daniel
1977 450 SEL 6.9 - Astralsilber

TJ 450

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Re: 6.9 Simple Fan Clutch Check
« Reply #10 on: 16 June 2020, 10:29 AM »
The 116 part no. isn’t really correct AFAIK but it’s about the only choice now.

I don’t think the original ones have been available for years.

Tim

1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

john erbe

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Re: 6.9 Simple Fan Clutch Check
« Reply #11 on: 16 June 2020, 10:34 AM »
I'm going to call them. The guy I usually deal with down there wasn't available via direct email. Message maybe lost in translation.

john erbe

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Re: 6.9 Simple Fan Clutch Check
« Reply #12 on: 16 June 2020, 12:53 PM »
In follow-up, daantjie your number is correct. That number they sent was for the 600. In any case it's NLA.

Randys01

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Re: 6.9 Simple Fan Clutch Check
« Reply #13 on: 18 June 2020, 11:50 PM »
Just to be clear folks....we are talking about the viscous  non electro magnetic fan coupling?
When cold it should turn with drag.  When the engine is running cold the fan speed is slowish. As it hots up the coupling starts to bind bringing the fan speedup to drive pulley speed.
Early devices relied on an oil coupling which got more viscous as it got hotter...these days it's a silicon of some sort. They are clever little gizmos.

UTn_boy

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Re: 6.9 Simple Fan Clutch Check
« Reply #14 on: 19 June 2020, 02:11 AM »
Randy,I don't think any W116 ever had an electro magnetic fan coupling.  That came about on the W201 and W124, didn't it? 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex