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Viscous Fan-Clutch behavior, What is "normal"

- - - - - Fan Clutch vicsous

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#1
TomOwen

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Folks,

 

I've been chasing a viscous issue for a while and it dawned on me that I should crowd-source some real info.

 

When the truck was new I recall the fan clutch engaged on first start and the fan "roaring" for a little while after driving. But that was it for almost the rest of the day. Maybe similar scenario when leaving office etc... but that's about it.

 

About a year ago, while contemplating cooling system issues I was pointed again to the fan clutch and realized it was no longer making noise on first start-up etc..  OK, so I am losing cooling efficiency there. 

 

I swapped out for aftermarket VFC and now the fan "roars" all-the-time". OK, almost.

 

First start - yup, runs for a couple minutes max.

Stop for coffee - yup, re-engaged after I get beck in truck

Stop for longer than pick up coffee - Yup, engaged for a couple minutes again

Tahoe in the WINTER? - YUP! Snow on hood, snow on bumper, snow on ground, snow in air... still engaged

Tahoe in SUMMER? - Yup. Cool mountain air down back side of summit on 80, Yup; cool mountain air on 89 returning from white rock? Yup

Altitude? Seems so. Fan stays engaged above about 3,000 feet elevation

 

I just replaced it again and so far, with the exception of elevation test, this seems to be exhibiting the same behavior.

 

QUESTION (finally):

 

A) Does any of this sound "normal" to you or your experience?

B) D1 owners - does your truck behave this way? No, what does your truck do?

 

Thanks for the help!! I think I see an order for Roverware.US in my future...  ;-)


:lr:
Tom Owen
NCLR Vice President

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'96 Discovery I, 122k, 5sp, RoverWare Bumper, Winch, ARB, BFGs, LEDs, OMEs, SD, etc...

On a slow transition from Carpool to Trail with the help of this Club

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; Cooper A/T3s, PacaSport, glitter, hair-bows, jolly ranchers and juice box stains...

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#2
AlysonH

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Hey Tom. You know I don't have a DI, but I had to replace the fan on my DII a few years ago and it pretty much did exactly what you're describing. The one that came on my truck was virtually quite and the replacement is super loud and seems to come on more even though the trucks temp remains the same. I inquired about this with the shop that installed it and also called a couple vendors that sell the parts and they pretty much told me the same thing: Land Rover would tinker around and change the fans several times in a year so even if you buy one spec'd for your year it will still sound different than the one you had. I don't know if this is an official reason for the DII fans, but they all told the same story.

By the way, on the way back from Hollister Saturday, I saw a DI exactly the same color as yours! At first I thought it was you because the color is so rare, but it was completely stock.

#3
RedRover

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Just out of curiosity, is it a 'bad' sound, or just a 'different' sound?  It seems like what Tom is describing is more a change in the frequency/occurrence in which the VC fan kicks in.

 

The part about the vehicle being buried in snow and the fan kicking in doesn't sound right, unless it's part of a startup sequence where the fan kicks on when you first start up the Rover.  If the engine is up to full operating temp and you're just sitting someplace, I suppose the fan might engage just to encourage airflow, but other than that, why would it turn on when moving?

 

I'm not a technician and I certainly haven't played one on television...


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Jared (KJ6MQI)
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#4
DHappel

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Most VC fans I've had spun up at first start when cold but stopped shortly after and didn't generally come back on unless things were heading for the red.  This is of dubious value as it's not D1 or even Rover specific, just general information.


Don
'07 LR3 HSE/HD - slightly non-stock

'96 D1 - even more non-stock


#5
AdvRovr

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At its heart, a viscous fan clutch is a viscous fan clutch and behave similarly regardless of vehicle make or model. When the car is cold, it should quickly disengage and free wheel. When the engine heats up, it should re-engage. Sounds like the new one is having issues disengaging. When you rev the engine before it hits operating temp, will the fan at least disengage at higher rpm?

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#6
DHappel

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I know this forum is anti-electric fan, but personally I've had good luck with them assuming they are correctly sized and shrouded.

 

Plus think of all the power savings from not driving that helicopter blade at high speed!


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Don
'07 LR3 HSE/HD - slightly non-stock

'96 D1 - even more non-stock


#7
AdvRovr

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I know this forum is anti-electric fan, but personally I've had good luck with them assuming they are correctly sized and shrouded.

Plus think of all the power savings from not driving that helicopter blade at high speed!


I'm not personally anti-electric fan, but it's worth noting that an electric fan doesn't actually provide any power savings over a *properly functioning* viscous fan, since the viscous fan should be freewheeling at anything besides the combination of high temperatures and low speeds.

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#8
nengelbrecht6

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Viscous fans should come on briefly when you start your engine. It takes a bit of time for the fluid in the clutch to warm up and be distributed around the clutch. Then, it shouldn't engage until the temp gets hot. The fact that it comes on whenever you start your truck isn't abnormal.

Not sure about the elevation change though. That's a weird one.

Nick

 

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#9
ColinB

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For Rovers in my experience they are on ALOT.   

 

Here is when they are on. 

 

A bit on start up.   The off until warm

 

Then ALWAYS when at operating temps at low to med speed.  IE under 50 mph.  

 

Then they taper off on the freeway. 

 

This does not seem to be true for other cars but rovers V8's GET HOT.  

 

 

Not as much on D2 and later rovers.      If I dont hear my VC fan in my rover then somthings wrong  Or i am on the freeway. 


 HAM KJ7RRC
95 LWB RRC 3 inch rte lt-230, 35x12.5/15 bfg km2, GBR 4.14 with trutracs front and rear, Rovertracks front Hd axles and cv's, Ashcroft Hd rear axles,
Rte rear trailing arms,Warn 8k, RTE bumpers front and rear with P-Fab Mods, Flowmaster exhaust ,custom sliders GRB F+R driveshaft, RTE steering links. 12 in Bilstien 7100's


#10
TomOwen

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Hey Tom. You know I don't have a DI, but I had to replace the fan on my DII a few years ago and it pretty much did exactly what you're describing. The one that came on my truck was virtually quite and the replacement is super loud and seems to come on more even though the trucks temp remains the same. I inquired about this with the shop that installed it and also called a couple vendors that sell the parts and they pretty much told me the same thing: Land Rover would tinker around and change the fans several times in a year so even if you buy one spec'd for your year it will still sound different than the one you had. I don't know if this is an official reason for the DII fans, but they all told the same story.

By the way, on the way back from Hollister Saturday, I saw a DI exactly the same color as yours! At first I thought it was you because the color is so rare, but it was completely stock.

Thanks.  Did you also notice a big hit to the already poor mileage?


:lr:
Tom Owen
NCLR Vice President

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'96 Discovery I, 122k, 5sp, RoverWare Bumper, Winch, ARB, BFGs, LEDs, OMEs, SD, etc...

On a slow transition from Carpool to Trail with the help of this Club

Y2K Toyota Land Cruiser Series 100
; Cooper A/T3s, PacaSport, glitter, hair-bows, jolly ranchers and juice box stains...

@TomOwen


#11
TomOwen

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For Rovers in my experience they are on ALOT.   

 

Here is when they are on. 

 

A bit on start up.   The off until warm

 

Then ALWAYS when at operating temps at low to med speed.  IE under 50 mph.  

 

Then they taper off on the freeway. 

 

This does not seem to be true for other cars but rovers V8's GET HOT.  

 

 

Not as much on D2 and later rovers.      If I dont hear my VC fan in my rover then somthings wrong  Or i am on the freeway. 

 Great info thanks.

 

Jared was spot on, it's a frequency issue.

 

A clutch is a clutch is a clutch regardless of make, yup.. but I added that for any particular model specific feedback on top of rest of good info ;-)

 

I get the theory of fluid settles when off and thus Fan engaged on 1st start... but should stay "warm" enough not to reengage after a few minutes off...

 

It *seems* to me that it comes on too often and, as I recall, more often than when the truck was new (and more often then when I thought the old clutch was bad ;-)   Ad I lost 2 or 3 MPG right off the bat (And No, I don't have too many extra of those!)

 

the motors do produce a ton of heat but I've been in nice, cool airflow 45-50-60 in Tahoe (coming back from WRL..complaining on the radio...) and still on... 

 

So in a binary worlds, the VC does not seem to be working correctly. 

 

Don, I would love to go all electric but that involves big or multi fans, proper shrouding, etc... more than I want to chew...

 

Thanks!!


:lr:
Tom Owen
NCLR Vice President

__________________________________________________________________________
'96 Discovery I, 122k, 5sp, RoverWare Bumper, Winch, ARB, BFGs, LEDs, OMEs, SD, etc...

On a slow transition from Carpool to Trail with the help of this Club

Y2K Toyota Land Cruiser Series 100
; Cooper A/T3s, PacaSport, glitter, hair-bows, jolly ranchers and juice box stains...

@TomOwen


#12
Lauroness

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Tom,

In my disco I've notice the in the higher altitudes the fan was kicking on more often then normal. Especially this last trip through the sierras. On Sunday exploring through Yosemite is when I started noticing how much it was actually kicking on. I did at time also have the a/c on. I myself run hot just like the v8 XD. But all and all fan kicks on a lot.
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#13
ColinB

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Also remember Fan Clutches are not On /Off.  They are variable.  


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 HAM KJ7RRC
95 LWB RRC 3 inch rte lt-230, 35x12.5/15 bfg km2, GBR 4.14 with trutracs front and rear, Rovertracks front Hd axles and cv's, Ashcroft Hd rear axles,
Rte rear trailing arms,Warn 8k, RTE bumpers front and rear with P-Fab Mods, Flowmaster exhaust ,custom sliders GRB F+R driveshaft, RTE steering links. 12 in Bilstien 7100's


#14
AlysonH

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Thanks. Did you also notice a big hit to the already poor mileage?


A bit, but this was around the time I changed out the bumper and I assumed it was the bumper causing the additional consumption.

#15
DHappel

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A bit, but this was around the time I changed out the bumper and I assumed it was the bumper causing the additional consumption.

I'd put more stock in the fan causing the mileage loss than the bumper.  Fans use a surprising amount of power from the engine when fully engaged.  Your bumper would add weight but that would only effect stop and go mileage and wouldn't have any noticeable effect on highway I should think.


Don
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'96 D1 - even more non-stock


#16
GraemeWare

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I just replaced it again and so far, with the exception of elevation test, this seems to be exhibiting the same behavior.

 

......

 

Thanks for the help!! I think I see an order for Roverware.US in my future...  ;-)

 

Tom,

 

You called?  Still using those Hayden fan couplings?

 

http://www.roverware...s-type-err3443/

 

You can buy cheap copies for $50-60 on Amazon too .... but that is your option ....

 

Regards,

 

Graeme


Graeme Ware -- San Carlos, CA

1990 Range Rover Classic - LT230 Transfer box, Warn winch, 2" lift, 235/85-16 Dunlop MUD Rovers, "Blue Submarine"
1996 Discovery 1 (R380 Manual Transmission, Ashcroft under-drive, RoverWare rear bumper, 33x12.5-15 BFG ATs) -- we call her "Katrina" -- Fordyce 7.5 mile survivor
1999 Discovery 2 (D1 CDL Linkage, 265/75-16 BFG A/T KO, RoverWare front and rear bumper)
1993 Jaguar XJS convertible; 1971 Triumph GT6; 1959 Morris Minor convertible
other assorted British pot metal ...


#17
TomOwen

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Tom,

 

You called?  Still using those Hayden fan couplings?

 

http://www.roverware...s-type-err3443/

 

You can buy cheap copies for $50-60 on Amazon too .... but that is your option ....

 

Regards,

 

Graeme

Well, well, well...  look who updated his website... imagine that... 

 

Thanks Graeme, I'll ping you when I find my discount code ... I hope it hasn't expired ;-)


:lr:
Tom Owen
NCLR Vice President

__________________________________________________________________________
'96 Discovery I, 122k, 5sp, RoverWare Bumper, Winch, ARB, BFGs, LEDs, OMEs, SD, etc...

On a slow transition from Carpool to Trail with the help of this Club

Y2K Toyota Land Cruiser Series 100
; Cooper A/T3s, PacaSport, glitter, hair-bows, jolly ranchers and juice box stains...

@TomOwen


#18
Timbo

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So - how can you test if working or not and engaging/disengaging properly. Have no idea if working properly .

Temp seems to be holding steady no matter what the outside temp - been quite a few +100f days round here Sind I moved.

#19
El Solis

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#20
GraemeWare

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What I've heard was when you get the truck up to temp, try to stop the fan w a rolled up newspaper. NOT YOUR FINGERS!!! If you can stop the fan then the VC has failed. Truck has to be up to operating temp.

 

Please don't do that.  If it has failed that badly then switching off and trying to turn the fan by hand will give you no resistance.  Putting newspapers into fans is more likely to shatter the fan and hurt someone ....

 

However, RoverWare.US do sell spares of those too ....ERR3439 .... at $39 for Bearmach, $80 for OEM, or $160 for Land Rover genuine, so you're free to try if you must.

 

Regards,

 

Graeme


Graeme Ware -- San Carlos, CA

1990 Range Rover Classic - LT230 Transfer box, Warn winch, 2" lift, 235/85-16 Dunlop MUD Rovers, "Blue Submarine"
1996 Discovery 1 (R380 Manual Transmission, Ashcroft under-drive, RoverWare rear bumper, 33x12.5-15 BFG ATs) -- we call her "Katrina" -- Fordyce 7.5 mile survivor
1999 Discovery 2 (D1 CDL Linkage, 265/75-16 BFG A/T KO, RoverWare front and rear bumper)
1993 Jaguar XJS convertible; 1971 Triumph GT6; 1959 Morris Minor convertible
other assorted British pot metal ...





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