It's one of those which should vary the drive to the fan as it gets hot.
But appears to run at the same slow speed even with the gauge going high
in heavy traffic, and the aux electric fans have cut in. At speed the temp
is fine.

I removed the coupling and tried heating the 'clock' spring with a hot air
gun and saw the valve move round, but the resistance to turning the shaft
by hand remained the same. If it were working normally, would the
resistance increase at what is effectively very low revs, ie turning it by
hand? Or only at much higher revs?

-- 
*If tennis elbow is painful, imagine suffering with tennis balls *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

"Dave Plowman (News)"  wrote in message 
news:4da7569012dave@davenoise.co.uk...

> It's one of those which should vary the drive to the fan as it gets hot.
> But appears to run at the same slow speed even with the gauge going high
> in heavy traffic, and the aux electric fans have cut in. At speed the temp
> is fine.
>
> I removed the coupling and tried heating the 'clock' spring with a hot air
> gun and saw the valve move round, but the resistance to turning the shaft
> by hand remained the same. If it were working normally, would the
> resistance increase at what is effectively very low revs, ie turning it by
> hand? Or only at much higher revs?
>
> -- 
> *If tennis elbow is painful, imagine suffering with tennis balls *
>
>    Dave Plowman        dave@davenoise.co.uk           London SW
>                  To e-mail, change noise into sound.


The unit should lock up practically solid as the heat increases.  Almost 
certainly I have a few of these fans in my garage.  I will have a look 
tomorrow and let you know.

mrcheerful

On Thu, 08 Sep 2005 21:18:18 +0100, Dave Plowman (News) wrote:


> It's one of those which should vary the drive to the fan as it gets hot.
> But appears to run at the same slow speed even with the gauge going high
> in heavy traffic, and the aux electric fans have cut in. At speed the temp
> is fine.
> 
> I removed the coupling and tried heating the 'clock' spring with a hot air
> gun and saw the valve move round, but the resistance to turning the shaft
> by hand remained the same. If it were working normally, would the
> resistance increase at what is effectively very low revs, ie turning it by
> hand? Or only at much higher revs?


My fathers BMW used to stiffen up as the temperture increase and spring
unwound. If you heated it with a hairdrier it would eventually lock almost
solid. Even so the electric aux fans would eventually kick in in a queue.

"Dave Plowman (News)"  wrote in message
news:4da7569012dave@davenoise.co.uk...

> It's one of those which should vary the drive to the fan as it gets hot.
> But appears to run at the same slow speed even with the gauge going high
> in heavy traffic, and the aux electric fans have cut in. At speed the temp
> is fine.
>
> I removed the coupling and tried heating the 'clock' spring with a hot air
> gun and saw the valve move round, but the resistance to turning the shaft
> by hand remained the same. If it were working normally, would the
> resistance increase at what is effectively very low revs, ie turning it by
> hand? Or only at much higher revs?
>


Firstly you should have a locked coupling at cold start after the oil has
settled into both parts. Holding the engine at ~2500rpm you should hear it
roaring for perhaps 5-10seconds afterwhich it should decay to the fan pretty
much freewheeling with no drive at all.

Heating the coupling should then progressively relock it.

Sounds like yours is fubar'd. Quite common.

Tim..

"Dave Plowman (News)"  wrote in message 
news:4da7569012dave@davenoise.co.uk...

> It's one of those which should vary the drive to the fan as it gets hot.
> But appears to run at the same slow speed even with the gauge going high
> in heavy traffic, and the aux electric fans have cut in. At speed the temp
> is fine.
>
> I removed the coupling and tried heating the 'clock' spring with a hot air
> gun and saw the valve move round, but the resistance to turning the shaft
> by hand remained the same. If it were working normally, would the
> resistance increase at what is effectively very low revs, ie turning it by
> hand? Or only at much higher revs?
>
> -- 
> *If tennis elbow is painful, imagine suffering with tennis balls *
>
>    Dave Plowman        dave@davenoise.co.uk           London SW
>                  To e-mail, change noise into sound.


I have got two viscous fans from earlier SD1 They have a hole through the 
middle and are secured to the pump by a nut in the middle on the radiator 
side.  They do not have a visible clock spring, the mechanism is internal 
(different manufacturer I guess) but if the fitting is the same they should 
fit.  Lakeside Essex free to collector.

mrcheerful

"mrcheerful ."  wrote in message 
news:0AeUe.105386$G8.30738@text.news.blueyonder.co.uk...

>
> "Dave Plowman (News)"  wrote in message 
> news:4da7569012dave@davenoise.co.uk...
>> It's one of those which should vary the drive to the fan as it gets hot.
>> But appears to run at the same slow speed even with the gauge going high
>> in heavy traffic, and the aux electric fans have cut in. At speed the 
>> temp
>> is fine.
>>
>> I removed the coupling and tried heating the 'clock' spring with a hot 
>> air
>> gun and saw the valve move round, but the resistance to turning the shaft
>> by hand remained the same. If it were working normally, would the
>> resistance increase at what is effectively very low revs, ie turning it 
>> by
>> hand? Or only at much higher revs?
>>
>> -- 
>> *If tennis elbow is painful, imagine suffering with tennis balls *
>>
>>    Dave Plowman        dave@davenoise.co.uk           London SW
>>                  To e-mail, change noise into sound.
>
> I have got two viscous fans from earlier SD1 They have a hole through the 
> middle and are secured to the pump by a nut in the middle on the radiator 
> side.  They do not have a visible clock spring, the mechanism is internal 
> (different manufacturer I guess) but if the fitting is the same they 
> should fit.  Lakeside Essex free to collector.
>
> mrcheerful

or were you talking about the bmw?

mrcheerful

In article <0AeUe.105386$G8.30738@text.news.blueyonder.co.uk>,
   mrcheerful                                                             
            .  wrote:

> I have got two viscous fans from earlier SD1 They have a hole through
> the middle and are secured to the pump by a nut in the middle on the
> radiator side.  They do not have a visible clock spring, the mechanism
> is internal (different manufacturer I guess) but if the fitting is the
> same they should fit.


Yes - earlier SD1 viscous couplings are like this. On the EFI engines they
have the standard left hand thread 'cap' nut fitting and are temperature
sensitive.

-- 
*If at first you don't succeed, then skydiving definitely isn't for you *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

as someone who has a bit of technical know-how, I'd be very tempted to make 
sure the vc wasn't fubar by waiting till it got hot and then stopping the 
fan with something (a big lump of wood with lots of towel warped round the 
end normally works if you are too scared to use your hands in 2 pairs of 
gloves :) )

if you can stop it it's fucked
if you can't then it's ok


"Dave Plowman (News)"  wrote in message 
news:4da7569012dave@davenoise.co.uk...

> It's one of those which should vary the drive to the fan as it gets hot.
> But appears to run at the same slow speed even with the gauge going high
> in heavy traffic, and the aux electric fans have cut in. At speed the temp
> is fine.
>
> I removed the coupling and tried heating the 'clock' spring with a hot air
> gun and saw the valve move round, but the resistance to turning the shaft
> by hand remained the same. If it were working normally, would the
> resistance increase at what is effectively very low revs, ie turning it by
> hand? Or only at much higher revs?
>
> -- 
> *If tennis elbow is painful, imagine suffering with tennis balls *
>
>    Dave Plowman        dave@davenoise.co.uk           London SW
>                  To e-mail, change noise into sound.