200Tdi - Viscous Fan / Overheating Question

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J

Jon

Guest
Hi all,

Sorry its a long post - please bear with me...

Vehicle: Defender 200Tdi

I have recently sent my 8 month old viscous fan unit back under
warrenty as I believed it was not functioning correctly. The fan was
much harder to turn when the engine was cold (i.e. first thing on a
morning) than it was after the engine had been running for a while.

On Saturday I received a new replacement unit. I put it on and got
the vehicle upto operating temperature (again reading hot on the
gauge). I then switched off the engine and tried to turn the fan.

With 1 finger I could make the fan spin quite freely. Given that the
engine is supposedly HOT (thermostat had definately opened and all
water hoses where hot to touch) I thought that there should be
significant resistance when spinning the fan????

In short this viscous unit is acting like the last 2 I have had so I
surely this must be an OK unit.

At what temperature do these things begin to show signs or resistance?


This whole issue has come about because the gauge reads about 1 needle
width off the end of the white on the gauge at 60-70mph - But never
goes into the red, even at 80mph, and it never boils.

I have had a new (re-cored) rad, new thermostat and new viscous fan.
I dont believe the head gasket has failed either (no visible signs in
oil or water or at the exhause).

I am fairly sure that all my earths are OK and the gauge does not act
in any strange way as you might associate with bad earths. However,
just to make sure I am going to wire the sender unit and guage direct
to the battery and see if that makes a difference.

Fail in that, are the sender units and or gauges prone to break down?
Does anyone know the part number and cost for a replacement
temperature sender unit??


Anti-freeze is at about 35% - 40% water mix.


Looking for some advice / pointers please...

Thanks
Jon

 
Jon wrote:

> Hi all,
>
> Sorry its a long post - please bear with me...
>
> Vehicle: Defender 200Tdi
>
> I have recently sent my 8 month old viscous fan unit back under
> warrenty as I believed it was not functioning correctly. The fan was
> much harder to turn when the engine was cold (i.e. first thing on a
> morning) than it was after the engine had been running for a while.
>
> On Saturday I received a new replacement unit. I put it on and got
> the vehicle upto operating temperature (again reading hot on the
> gauge). I then switched off the engine and tried to turn the fan.
>
> With 1 finger I could make the fan spin quite freely. Given that the
> engine is supposedly HOT (thermostat had definately opened and all
> water hoses where hot to touch) I thought that there should be
> significant resistance when spinning the fan????
>
> In short this viscous unit is acting like the last 2 I have had so I
> surely this must be an OK unit.
>
> At what temperature do these things begin to show signs or resistance?
>
>

Umm - If I'm thinking of the right thing, there's no temperature
relationship, merely engine speed - the faster the engine turns the faster
the fan goes, just not at a 1:1 rate.

The viscous coupling is sort of like the torque convertor in an automatic
gearbox - the faster one side of it moves, the faster the other side moves
with the actual movement relying on the oil between to carry it.

P.
--
1992 200 TDI Disco - heavily modified
1982 V8 Range Rover - heavily corroded
2000 Rover 75 - heavily driven
1993 Lexus LS400 - just plain heavy on fuel
 

>>
>
>Umm - If I'm thinking of the right thing, there's no temperature
>relationship, merely engine speed - the faster the engine turns the faster
>the fan goes, just not at a 1:1 rate.
>
Well, you learn something every day. I had always thought it was
temperature related.

>The viscous coupling is sort of like the torque convertor in an automatic
>gearbox - the faster one side of it moves, the faster the other side moves
>with the actual movement relying on the oil between to carry it.
>
>P.

 
On or around Mon, 4 Jul 2005 11:32:16 +0000 (UTC), Jon <[email protected]>
enlightened us thusly:

>At what temperature do these things begin to show signs or resistance?

fecking hot. Basically, it's only going to spin up under severe
provocation. They all start off stiff when cold, they should then go free
or nearly-free once run for about 30 seconds or so at moderate engine
speeds. At 80 mph, it's unlikely to 'cos there's lots of airflow anyway.

The only time I've had one spin up again in earnest was when tuning an LPG
system, running at 3000 rpm for several minutes with the vehicle stationary.

>This whole issue has come about because the gauge reads about 1 needle
>width off the end of the white on the gauge at 60-70mph - But never
>goes into the red, even at 80mph, and it never boils.
>
>I have had a new (re-cored) rad, new thermostat and new viscous fan.
>I dont believe the head gasket has failed either (no visible signs in
>oil or water or at the exhause).

replace the sender unit on the engine.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".
 

>Umm - If I'm thinking of the right thing, there's no temperature
>relationship, merely engine speed - the faster the engine turns the faster
>the fan goes, just not at a 1:1 rate.
>
>The viscous coupling is sort of like the torque convertor in an automatic
>gearbox - the faster one side of it moves, the faster the other side moves
>with the actual movement relying on the oil between to carry it.
>
>P.

That can't be right Paul - you'd never get any cooling when idling
which is precisely when you need it most (when no air is flowing over
the rad due to vehicle speed).

Pretty sure it's temp related....


--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'03 Volvo V70
 

"Jon" <[email protected]> wrote in message
news:[email protected]...
>
>>>
>>
>>Umm - If I'm thinking of the right thing, there's no temperature
>>relationship, merely engine speed - the faster the engine turns the faster
>>the fan goes, just not at a 1:1 rate.
>>
> Well, you learn something every day. I had always thought it was
> temperature related.

It is!

>
>>The viscous coupling is sort of like the torque convertor in an automatic
>>gearbox - the faster one side of it moves, the faster the other side moves
>>with the actual movement relying on the oil between to carry it.

Sort of correct, except the oil is a silicon based fluid that is only
allowed to flow into the drive chamber under centrifugal force of the
rotating hub, as the bi-metallic spring opens the valve ports.
The viscous fan is often blamed for temp related issues, when there is in
fact nothing wrong with it. It is an extremely reliable piece of kit that
rarely goes wrong. I'd look at your temp indication system first, my initial
port of call would be the sender unit.
Badger.


 
Sorry, another longish post but help and advice is needed!

Thought Id check out my electrics tonight before replacing the sender
unit.

When sender unit is unplugged and wire shorted to earth, guage shoots
over to beyond the red (as it should).

Does anyone know what voltage I should have at the Water Temperature
Sender Unit?? 12V or 5V??? I have 5V, give or take a bit...

12V gets fed into the temperature gauge and 5V comes out and goes to
the sender unit.

However, I have 2 black wires (apparently to earth) connected together
in 1 bango type connector which is attached to the holding / fixing
screw on the back of the temp gauge. If I remove this I get 12V out
of the temp gauge and 12V to the sender unit.

When 12V goes through the sender unit the gauge reads (with a cool
engine) somewhere in the red - clearly incorrect.

I have checked the Haynes manual and cant see any mention of these
black wires connected to the gauge - Are they supposed to be there?
Coincidently there is the same arrangement to the rear of the fuel
gauge?

I have also removed the gauge to check continuity through the +12V to
the holding screw and there is a path through - Is this correct as I
was expecting the screw to be isolated from the gauge body.

Thanks again for advice & pointers.
Jon



On Mon, 04 Jul 2005 13:58:15 +0100, Austin Shackles
<[email protected]> wrote:

>On or around Mon, 4 Jul 2005 11:32:16 +0000 (UTC), Jon <[email protected]>
>enlightened us thusly:
>
>>At what temperature do these things begin to show signs or resistance?
>
>fecking hot. Basically, it's only going to spin up under severe
>provocation. They all start off stiff when cold, they should then go free
>or nearly-free once run for about 30 seconds or so at moderate engine
>speeds. At 80 mph, it's unlikely to 'cos there's lots of airflow anyway.
>
>The only time I've had one spin up again in earnest was when tuning an LPG
>system, running at 3000 rpm for several minutes with the vehicle stationary.
>
>>This whole issue has come about because the gauge reads about 1 needle
>>width off the end of the white on the gauge at 60-70mph - But never
>>goes into the red, even at 80mph, and it never boils.
>>
>>I have had a new (re-cored) rad, new thermostat and new viscous fan.
>>I dont believe the head gasket has failed either (no visible signs in
>>oil or water or at the exhause).
>
>replace the sender unit on the engine.

 
Evening guys

I too would be very interested in this info as my 200tdi defender is doing the exact same thing and is also on its 3rd viscous unit!! I have also changed the head gasket, water pump, thermostat, sender and rad and am now stuck.
I would of thought that when the engine is cold the fan should spin slowly increasing to engine speed when the engine is hot and the hot air that passes through the rad. But you can stop mine easily when warm!!
Graham
 
On or around Tue, 5 Jul 2005 20:38:49 +0000 (UTC), Jon
<[email protected]> enlightened us thusly:

>12V gets fed into the temperature gauge and 5V comes out and goes to
>the sender unit.
>

mostly, the temperature gauge is an ammeter. Basically, the resistance of
the sender changes with temperature, resulting in more or less current
flowing. There are 2 ways of doing it: more current = more deflection is
common, as proved by the thing going to the top of the dial when you earth
the other end.

The sender can get senile in various ways.

interestingly, the somewhat out of date intermotor book I have here doesn't
list the temp sender for the TDi engines. Which is a pity, 'cos if it did,
I could've got the specs for it for you.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".
 
Austin,
Thanks for looking in the book. Have you any ideas if those curious 2
black wires (earths?) should be connected to the fixing screw at the
rear of the gauge?



I wonder if someone could possibly measure the voltage between the
sender unit and its supply lead as this would appear to be key. I am
guessing it should be 12V (not 5V like mine) and thus the sender is
stuffed, however, if it should be 5V the quest still remains!


Graham:
Out of interest, as your gauge is reading incorrect, what voltage have
you got at the sender unit?

Thanks
Jon

On Tue, 05 Jul 2005 22:57:10 +0100, Austin Shackles
<[email protected]> wrote:

>On or around Tue, 5 Jul 2005 20:38:49 +0000 (UTC), Jon
><[email protected]> enlightened us thusly:
>
>>12V gets fed into the temperature gauge and 5V comes out and goes to
>>the sender unit.
>>
>
>mostly, the temperature gauge is an ammeter. Basically, the resistance of
>the sender changes with temperature, resulting in more or less current
>flowing. There are 2 ways of doing it: more current = more deflection is
>common, as proved by the thing going to the top of the dial when you earth
>the other end.
>
>The sender can get senile in various ways.
>
>interestingly, the somewhat out of date intermotor book I have here doesn't
>list the temp sender for the TDi engines. Which is a pity, 'cos if it did,
>I could've got the specs for it for you.

 
On or around Tue, 5 Jul 2005 22:43:55 +0000, Graham Wilkinson
<[email protected]> enlightened us thusly:

>I would of thought that when the engine is cold the fan should spin
>slowly increasing to engine speed when the engine is hot and the hot
>air that passes through the rad. But you can stop mine easily when
>warm!!

OK, viscous fans in a nutshell:

(If it's working properly)

Initially on cold start-up: fan spins fast, makes a lot of noise on a V8
one.

After about 30sec or so (more if it's at idle): fan frees off and spins
down. You can hear it do that quite clearly on a V8, less so on a TDi
thanks to more engine noise and more sound deadening. Try it with the
bonnet up - start the engine, run it at about 2000 rpm and watch/listen to
the fan, after a bit you should see and hear it slow down.

Normal running - engine at normal temp: fan stays free. Minor overheat such
as climbing a big hill in low gear doesn't generally make it hot enough to
cut back in.

Engine overheating or working hard and stationary: fan will cut back in and
spin up again, but it needs to be pretty hot to achieve this. If it
actually boils, without the fan cutting in, then you can reasonably say that
it's not working. The times I've seen one cut in were doing silly stuff
like tuning the gas system, running at 3000 rpm in the workshop for several
minutes. When the fan comes in, it's unmistakable. Quite honestly, I doubt
you can provoke a TDi into doing that - they run cold, normally, unless
there's an actual fault. I guess you'd only really need the fan in heavy
slow towing or other extreme conditions like sustained winching, maybe.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".
 
OK, replaced the sender last night with new (genuine) one.

Exactly the same temperature readings...bugger!

Some nice chap on the LRO Forum also confirmed that the voltage to the
sender should be between about 4.5V - fine there then.

That leaves me with 2 options:-
1. Gauge is faulty (doubt that)
2. Engine is actually running hot

I now suspect that my engine is running a bit too hot...Question is
what would cause that?

I did notice last night that when hot (never noticed it when cold) I
get a bit of air/oil vapour blowing out from under the oil filler cap.
I have known for some time that the oil breather that feeds to the air
filter puffs oily vapour out, but isnt that what its supposed to do?

What would cause pressure in the rocker box, enough to blow through
the filler (a breather blocked somewhere), and would this cause it to
run hot??

Thanks
Jon


On Tue, 5 Jul 2005 20:38:49 +0000 (UTC), Jon
<[email protected]> wrote:

>Sorry, another longish post but help and advice is needed!
>
>Thought Id check out my electrics tonight before replacing the sender
>unit.
>
>When sender unit is unplugged and wire shorted to earth, guage shoots
>over to beyond the red (as it should).
>
>Does anyone know what voltage I should have at the Water Temperature
>Sender Unit?? 12V or 5V??? I have 5V, give or take a bit...
>
>12V gets fed into the temperature gauge and 5V comes out and goes to
>the sender unit.
>
>However, I have 2 black wires (apparently to earth) connected together
>in 1 bango type connector which is attached to the holding / fixing
>screw on the back of the temp gauge. If I remove this I get 12V out
>of the temp gauge and 12V to the sender unit.
>
>When 12V goes through the sender unit the gauge reads (with a cool
>engine) somewhere in the red - clearly incorrect.
>
>I have checked the Haynes manual and cant see any mention of these
>black wires connected to the gauge - Are they supposed to be there?
>Coincidently there is the same arrangement to the rear of the fuel
>gauge?
>
>I have also removed the gauge to check continuity through the +12V to
>the holding screw and there is a path through - Is this correct as I
>was expecting the screw to be isolated from the gauge body.
>
>Thanks again for advice & pointers.
>Jon
>
>
>
>On Mon, 04 Jul 2005 13:58:15 +0100, Austin Shackles
><[email protected]> wrote:
>
>>On or around Mon, 4 Jul 2005 11:32:16 +0000 (UTC), Jon <[email protected]>
>>enlightened us thusly:
>>
>>>At what temperature do these things begin to show signs or resistance?
>>
>>fecking hot. Basically, it's only going to spin up under severe
>>provocation. They all start off stiff when cold, they should then go free
>>or nearly-free once run for about 30 seconds or so at moderate engine
>>speeds. At 80 mph, it's unlikely to 'cos there's lots of airflow anyway.
>>
>>The only time I've had one spin up again in earnest was when tuning an LPG
>>system, running at 3000 rpm for several minutes with the vehicle stationary.
>>
>>>This whole issue has come about because the gauge reads about 1 needle
>>>width off the end of the white on the gauge at 60-70mph - But never
>>>goes into the red, even at 80mph, and it never boils.
>>>
>>>I have had a new (re-cored) rad, new thermostat and new viscous fan.
>>>I dont believe the head gasket has failed either (no visible signs in
>>>oil or water or at the exhause).
>>
>>replace the sender unit on the engine.

 
In message <[email protected]>
Jon <[email protected]> wrote:

> OK, replaced the sender last night with new (genuine) one.
>
> Exactly the same temperature readings...bugger!
>
> Some nice chap on the LRO Forum also confirmed that the voltage to the
> sender should be between about 4.5V - fine there then.
>
> That leaves me with 2 options:-
> 1. Gauge is faulty (doubt that)
> 2. Engine is actually running hot
>
> I now suspect that my engine is running a bit too hot...Question is
> what would cause that?
>
> I did notice last night that when hot (never noticed it when cold) I
> get a bit of air/oil vapour blowing out from under the oil filler cap.
> I have known for some time that the oil breather that feeds to the air
> filter puffs oily vapour out, but isnt that what its supposed to do?
>
> What would cause pressure in the rocker box, enough to blow through
> the filler (a breather blocked somewhere), and would this cause it to
> run hot??
>
> Thanks
> Jon
>

Run the engine with the oil filler cap off - does it "chuff" (sounds
a bit like a subdued pop-pop)? Again, run the engine with the dipstick
removed (at idle!) - is there a chuffing though there? Finally, is the
air filter oily (i.e. more than just a little bit on the lower front
end of the filter? If any/all of the above are present, then the head
gasket is suspect. If there is only slight evidence of the above then
get a compression test done (don't know if you have already done
that) - you should be looking for one or two cylinders being a lower
than the others - Nos. 3 and 4 are the usual culprits on 200Tdi's.

If the above are all clear, then a cracked head would be the next
thing to investigate.

Richard


>
> On Tue, 5 Jul 2005 20:38:49 +0000 (UTC), Jon
> <[email protected]> wrote:
>
> >Sorry, another longish post but help and advice is needed!
> >
> >Thought Id check out my electrics tonight before replacing the sender
> >unit.
> >
> >When sender unit is unplugged and wire shorted to earth, guage shoots
> >over to beyond the red (as it should).
> >
> >Does anyone know what voltage I should have at the Water Temperature
> >Sender Unit?? 12V or 5V??? I have 5V, give or take a bit...
> >
> >12V gets fed into the temperature gauge and 5V comes out and goes to
> >the sender unit.
> >
> >However, I have 2 black wires (apparently to earth) connected together
> >in 1 bango type connector which is attached to the holding / fixing
> >screw on the back of the temp gauge. If I remove this I get 12V out
> >of the temp gauge and 12V to the sender unit.
> >
> >When 12V goes through the sender unit the gauge reads (with a cool
> >engine) somewhere in the red - clearly incorrect.
> >
> >I have checked the Haynes manual and cant see any mention of these
> >black wires connected to the gauge - Are they supposed to be there?
> >Coincidently there is the same arrangement to the rear of the fuel
> >gauge?
> >
> >I have also removed the gauge to check continuity through the +12V to
> >the holding screw and there is a path through - Is this correct as I
> >was expecting the screw to be isolated from the gauge body.
> >
> >Thanks again for advice & pointers.
> >Jon
> >
> >
> >
> >On Mon, 04 Jul 2005 13:58:15 +0100, Austin Shackles
> ><[email protected]> wrote:
> >
> >>On or around Mon, 4 Jul 2005 11:32:16 +0000 (UTC), Jon <[email protected]>
> >>enlightened us thusly:
> >>
> >>>At what temperature do these things begin to show signs or resistance?
> >>
> >>fecking hot. Basically, it's only going to spin up under severe
> >>provocation. They all start off stiff when cold, they should then go free
> >>or nearly-free once run for about 30 seconds or so at moderate engine
> >>speeds. At 80 mph, it's unlikely to 'cos there's lots of airflow anyway.
> >>
> >>The only time I've had one spin up again in earnest was when tuning an LPG
> >>system, running at 3000 rpm for several minutes with the vehicle stationary.
> >>
> >>>This whole issue has come about because the gauge reads about 1 needle
> >>>width off the end of the white on the gauge at 60-70mph - But never
> >>>goes into the red, even at 80mph, and it never boils.
> >>>
> >>>I have had a new (re-cored) rad, new thermostat and new viscous fan.
> >>>I dont believe the head gasket has failed either (no visible signs in
> >>>oil or water or at the exhause).
> >>
> >>replace the sender unit on the engine.
>

--
www.beamends-lrspares.co.uk [email protected]
Running a business in a Microsoft free environment - it can be done
Powered by Risc-OS - you won't get a virus from us!!
Helping keep Land Rovers on and off the road to annoy the Lib Dems
 
Richard,
Many thanks for this. I will check these things out at the weekend
and see what noises I can hear.

As for the compression test - havent done this yet. What should would
be an acceptable compression? I know that it is more important to
have 4 equal'ish pots but what value would you expect them to be?

Thanks
Jon

On Fri, 8 Jul 2005 08:10:27 +0000 (UTC), beamendsltd
<[email protected]> wrote:

>In message <[email protected]>
> Jon <[email protected]> wrote:
>
>> OK, replaced the sender last night with new (genuine) one.
>>
>> Exactly the same temperature readings...bugger!
>>
>> Some nice chap on the LRO Forum also confirmed that the voltage to the
>> sender should be between about 4.5V - fine there then.
>>
>> That leaves me with 2 options:-
>> 1. Gauge is faulty (doubt that)
>> 2. Engine is actually running hot
>>
>> I now suspect that my engine is running a bit too hot...Question is
>> what would cause that?
>>
>> I did notice last night that when hot (never noticed it when cold) I
>> get a bit of air/oil vapour blowing out from under the oil filler cap.
>> I have known for some time that the oil breather that feeds to the air
>> filter puffs oily vapour out, but isnt that what its supposed to do?
>>
>> What would cause pressure in the rocker box, enough to blow through
>> the filler (a breather blocked somewhere), and would this cause it to
>> run hot??
>>
>> Thanks
>> Jon
>>
>
>Run the engine with the oil filler cap off - does it "chuff" (sounds
>a bit like a subdued pop-pop)? Again, run the engine with the dipstick
>removed (at idle!) - is there a chuffing though there? Finally, is the
>air filter oily (i.e. more than just a little bit on the lower front
>end of the filter? If any/all of the above are present, then the head
>gasket is suspect. If there is only slight evidence of the above then
>get a compression test done (don't know if you have already done
>that) - you should be looking for one or two cylinders being a lower
>than the others - Nos. 3 and 4 are the usual culprits on 200Tdi's.
>
>If the above are all clear, then a cracked head would be the next
>thing to investigate.
>
>Richard
>
>
>>
>> On Tue, 5 Jul 2005 20:38:49 +0000 (UTC), Jon
>> <[email protected]> wrote:
>>
>> >Sorry, another longish post but help and advice is needed!
>> >
>> >Thought Id check out my electrics tonight before replacing the sender
>> >unit.
>> >
>> >When sender unit is unplugged and wire shorted to earth, guage shoots
>> >over to beyond the red (as it should).
>> >
>> >Does anyone know what voltage I should have at the Water Temperature
>> >Sender Unit?? 12V or 5V??? I have 5V, give or take a bit...
>> >
>> >12V gets fed into the temperature gauge and 5V comes out and goes to
>> >the sender unit.
>> >
>> >However, I have 2 black wires (apparently to earth) connected together
>> >in 1 bango type connector which is attached to the holding / fixing
>> >screw on the back of the temp gauge. If I remove this I get 12V out
>> >of the temp gauge and 12V to the sender unit.
>> >
>> >When 12V goes through the sender unit the gauge reads (with a cool
>> >engine) somewhere in the red - clearly incorrect.
>> >
>> >I have checked the Haynes manual and cant see any mention of these
>> >black wires connected to the gauge - Are they supposed to be there?
>> >Coincidently there is the same arrangement to the rear of the fuel
>> >gauge?
>> >
>> >I have also removed the gauge to check continuity through the +12V to
>> >the holding screw and there is a path through - Is this correct as I
>> >was expecting the screw to be isolated from the gauge body.
>> >
>> >Thanks again for advice & pointers.
>> >Jon
>> >
>> >
>> >
>> >On Mon, 04 Jul 2005 13:58:15 +0100, Austin Shackles
>> ><[email protected]> wrote:
>> >
>> >>On or around Mon, 4 Jul 2005 11:32:16 +0000 (UTC), Jon <[email protected]>
>> >>enlightened us thusly:
>> >>
>> >>>At what temperature do these things begin to show signs or resistance?
>> >>
>> >>fecking hot. Basically, it's only going to spin up under severe
>> >>provocation. They all start off stiff when cold, they should then go free
>> >>or nearly-free once run for about 30 seconds or so at moderate engine
>> >>speeds. At 80 mph, it's unlikely to 'cos there's lots of airflow anyway.
>> >>
>> >>The only time I've had one spin up again in earnest was when tuning an LPG
>> >>system, running at 3000 rpm for several minutes with the vehicle stationary.
>> >>
>> >>>This whole issue has come about because the gauge reads about 1 needle
>> >>>width off the end of the white on the gauge at 60-70mph - But never
>> >>>goes into the red, even at 80mph, and it never boils.
>> >>>
>> >>>I have had a new (re-cored) rad, new thermostat and new viscous fan.
>> >>>I dont believe the head gasket has failed either (no visible signs in
>> >>>oil or water or at the exhause).
>> >>
>> >>replace the sender unit on the engine.
>>

 
>
>Sort of correct, except the oil is a silicon based fluid that is only
>allowed to flow into the drive chamber under centrifugal force of the
>rotating hub, as the bi-metallic spring opens the valve ports.
>The viscous fan is often blamed for temp related issues, when there is in
>fact nothing wrong with it. It is an extremely reliable piece of kit that
>rarely goes wrong. I'd look at your temp indication system first, my initial
>port of call would be the sender unit.
>Badger.
>

<pet hate>
Centripetal force (or, in fact, lack thereof...)
</pet hate>

:)



--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'03 Volvo V70
 

"Tim Hobbs" <[email protected]> wrote in message
news:eek:[email protected]...
> >
>>Sort of correct, except the oil is a silicon based fluid that is only
>>allowed to flow into the drive chamber under centrifugal force of the
>>rotating hub, as the bi-metallic spring opens the valve ports.
>>The viscous fan is often blamed for temp related issues, when there is in
>>fact nothing wrong with it. It is an extremely reliable piece of kit that
>>rarely goes wrong. I'd look at your temp indication system first, my
>>initial
>>port of call would be the sender unit.
>>Badger.
>>
>
> <pet hate>
> Centripetal force (or, in fact, lack thereof...)
> </pet hate>
>
> :)
>

I didn't want to confuse the issue Tim! People understand centrifugal force,
a lot have never even heard of centripetal force.
Badger.


 
Badger wrote:
>><pet hate>
>>Centripetal force (or, in fact, lack thereof...)
>></pet hate>
>>
>>:)
>>
>
>
> I didn't want to confuse the issue Tim! People understand centrifugal force,
> a lot have never even heard of centripetal force.
> Badger.
>
>

Its all a matter of perspective. You can't have one without the other.

Steve
 
On Fri, 08 Jul 2005 19:08:12 +0100, steve Taylor
<[email protected]> wrote:

>Badger wrote:
>>><pet hate>
>>>Centripetal force (or, in fact, lack thereof...)
>>></pet hate>
>>>
>>>:)
>>>
>>
>>
>> I didn't want to confuse the issue Tim! People understand centrifugal force,
>> a lot have never even heard of centripetal force.
>> Badger.
>>
>>
>
>Its all a matter of perspective. You can't have one without the other.
>
>Steve

Except that there is no such thing as centrifugal force. It doesn't
exist.

--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'03 Volvo V70
 
Tim Hobbs wrote:

> Except that there is no such thing as centrifugal force. It doesn't
> exist.
>

Oh yes it does.

From the perspective of the support around which a mass spins, of course
it does. Does the support feel the spinning mass pushing it, or pulling
it ? Is your frame of reference fixed or rotating ? If its rotating, as
it is in your physical experience with a lump on a rope say, then *you*
experience a centrifugal force.

Of course, if the force really was acting through the centre of mass of
the object and the centre of rotation, it would fly away radially, and
not tangentially, so we know that the action from the rotating masses
point of view is towards the centre, since the mass wishes to travel in
a straight line in the absence of any external forces.

Steve
 

"steve Taylor" <[email protected]> wrote in message
news:[email protected]...
> Tim Hobbs wrote:
>
>> Except that there is no such thing as centrifugal force. It doesn't
>> exist.
>>
>
> Oh yes it does.
>
> From the perspective of the support around which a mass spins, of course
> it does. Does the support feel the spinning mass pushing it, or pulling
> it ? Is your frame of reference fixed or rotating ? If its rotating, as
> it is in your physical experience with a lump on a rope say, then *you*
> experience a centrifugal force.
>
> Of course, if the force really was acting through the centre of mass of
> the object and the centre of rotation, it would fly away radially, and
> not tangentially, so we know that the action from the rotating masses
> point of view is towards the centre, since the mass wishes to travel in
> a straight line in the absence of any external forces.
>
> Steve

Aaaarrrgghhhhh! Is reality is an illusion caused by lack of alcohol, or is
reality having no money to buy alcohol to induce illusions....??
Centrifugal, centripetal, who really cares? In the context of the
description of operation of a viscous hub the force represents the tendancy
for the fluid to be displaced outwards within the hub's perimeter due to it
rotating. That's all we need to know. :)
Badger.
(wishing he'd never bothered to answer the original question)


 
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