Bye bye electric, hello viscous

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cappers

cappers

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Today I removed the 12" Kenlowe pusher fan and reinstalled the 11 blade viscous fan and hub.

I never felt that a single 12" fan was enough for a V8 and although it did the job, in the recent hot weather in slow moving traffic the engine temperature has has been cycling up and down, 80-100, averaging high 80s-low 90s. It was only used because it came with the original 2.5P and when it was converted to a V8 there was no fan shroud for the viscous and the consensus was without a shroud the viscous would not be much use. But I don't like the electric fan and have to keep an eye on the temp gauge and wait for it to kick in when I think it's getting too hot. However as the viscous fan sits very close the rad (the hub is about 2" behind the rad) and I figured it couldn't be worse than the electric, even without the shroud, and it moves far more air than the electric.

Went for a drive, mix of town traffic, country lanes, fast A road and then town traffic again. Temp went to high 80s as stat opened then went down to low 80s and stayed there no matter the driving conditions. Obviously the ambient temps are lower than a few weeks ago but even in the current weather the electric fan came on in slow traffic.

I have a ?V8 shroud and with a bit of modification and fettling should be able to make it fit. That will concentrate the suction over the whole rad and protect fingers and make it look correct.

If things go wrong I'll post my findings but I think (hope) this is going to work OK.

P.S. It sounds better now IMO! There is the quiet roar of the fan, obviously when cold and locked but even freewheeling there is an underlying propeller sound!
 
flat said:
I ditched my electric for exactly the same reason!
Click to expand...
@flat
Do you have a shroud? If not, is your cooling OK? My previous V8s had viscous fans and shrouds and never gave me a problem.
Not sure why, possibly to do with putting a Disco V8 and ZF box in a 90 although it was mounted in the factory position, but the fan sits slightly off centre to the rad.
Screenshot 2020-09-12 at 22.03.52.png

This means some mods are needed for the shroud I have.
 
Always run the viscous fan on my V8 and only have a small rad 15" x 18" four core thick with no over heating problems
 
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I do have a shroud yes. I didn’t to start but since fitting I haven’t noticed much difference but Land Rover wouldnt have made it if it wasn’t needed so I fitted one! Makes it look neat aswell
 
capo said:
There is the quiet roar of the fan, obviously when cold and locked but even freewheeling there is an underlying propeller sound!
Click to expand...
When cold it should spin freely.
With the engine cold and switched off turn the fan with your fingers.
After some resistance it should free up & spin with little resistance.
As the engine warms the viscous coupling will heat up & cause the fan to lock up.

Might be of interest:
 
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capo said: ↑
There is the quiet roar of the fan, obviously when cold and locked but even freewheeling there is an underlying propeller sound!
Ratae said:
When cold it should spin freely.
With the engine cold and switched off turn the fan with your fingers.
After some resistance it should free up & spin with little resistance.
As the engine warms the viscous coupling will heat up & cause the fan to lock up.

Might be of interest:
Click to expand...


I should have written "...roar of the fan, initially when cold for a few seconds, and when locked at temperature...etc"
 
Huddy84 said:
Goes to show Landrover knew what they were doing fitting viscous.
Click to expand...

Not just LR of that period. I'm about to renew the shroud on my daily BMW as pieces of the plastic are missing. I'm assuming these gaps must ultimately prevent the viscous being at peak efficiency, as although the temp never goes above normal the auxiliary electric fans often cut in briefly.
 
capo said:
capo said: ↑
There is the quiet roar of the fan, obviously when cold and locked but even freewheeling there is an underlying propeller sound

I should have written "...roar of the fan, initially when cold for a few seconds, and when locked at temperature...etc"
Click to expand...

More than a few seconds in my disco although no more than driving the first 100 metres down the the road from cold, only to return in traffic on a hot day.

The reasion for the "roar" is as stated in LRs work shop manual:
Starting engine from cold
During the time the engine is at rest the silicone fluid drains down, half filling chambers A and B. Thus when the engine is first started sufficient fluid is present in chamber A to provide a positive drive between the members, as is evident by the initial noise of the fan.
However within a very short period of time, after starting the engine, the fan speed and noise will decline indicating that the fluid is being centrifuged into chamber B causing the drive to slip.
Hot conditions
When operating in high ambient temperatures or when stationary in traffic, the bi-metal thermostat will operate and open the valve port between chambers A and B.Opening the valve allows the fluid to circulate between the two members, causing the unit to couple, thus increasing the fan speed and cooling effect.
 
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I can now hear the 'whoosh' of the fan like in my previous V8s :D The cold start roar soon dies down but the background whoosh remains especially on acceleration, and I like it!:rolleyes:
Driving around today, once up to temp the gauge was steady, and at the end of a run the engine bay felt much cooler.
 
Since removing the electric fan and fitting the viscous fan the engine has stayed at a constant running temp (low 80s) even in slow moving stop-start traffic during the hot spell the other day (28-30C ambient) This is without the fan shroud so I'm happy.
However a number of web posts state that without a shroud the fan is far less effective and as I had an old V8 one lying about which doesn't fit as is, I decided to do some surgery on it. Short story, I cut it in half and secured the top half to the rad.
Fan is central to the now half hole with a 1" gap between the blade tips and the shroud and the blades are about 2" away from the rad. It looks neater and saves any stray fingers from touching the fan. A kitchen cloth draped on the louvre panel with the engine idling from cold was sucked to the panel, very strongly in the centre and also on the sides away from the fan enough to keep it suspended.
Will keep an eye on temp but I think this set up works fine.
IMG_1979.JPG
IMG_1980.JPG
IMG_1982.JPG
IMG_1983.JPG
IMG_1984.JPG
 
Andy J said:
HI great looking cowl. What water pump is that as I've been trying to locate a twin 'v' pulley for mine Cheers.
Click to expand...
It's a 1992 Disco 1 3.5 V8 Efi non-serpentine and I assume the appropriate water pump fitted to that e.g. STC483?....not sure about the pulley.
 
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