Member Since: 31 Dec 2021
Location: Taranaki
Posts: 258
Viscous fan speed petrol engine
Hi all.
Just a query regards my viscous fan speed. Live value taken a couple of minutes after starting, hence the engine temp of only 55oC.
Is a viscous fan speed of 868 normal or do I have something wrong?
I feel the fan really "roars", sometimes it quietens down after a few minutes. This is the first time I've thought to look at its speed using live values on GAP IID.
Note. Vehicle is stationary, parked in driveway.
Thanks
Blake
14th Jul 2023 2:35 am
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 258
I've just been for a test drive. Viscous fan runs at approx 380 with engine speed of approx 760 rpm. Fan running nice snd quite, so I'm assuming all OK.
Thanks Blake
14th Jul 2023 4:46 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8154
The D3 does fan does tend to roar for a short time on cold start up, possibly a minute.It can when others can't,
It will when others won't,
It goes where others don't.
14th Jul 2023 7:02 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10478
IT is also electrically controlled.
The roar is a self test to ensure the electric control works.
I expect it’s fine
14th Jul 2023 7:04 am
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 258
Great. Thanks for the clarification guys.
14th Jul 2023 9:03 am
KPTV8
Member Since: 05 Feb 2012
Location: Itinerant !! (Scotland/Donegal)
Posts: 153
Before I moved house out to rural, my neighbour would be woken from slumbers when I started my D3 V8 for early morning commutes - yes the revs immediately spike (see ** below) and the fan roars as soon as you pull away. I never did the following mod - wanted a switch to bypass the fan viscous coupler action so I could suppress the fan until the engine is warm; I'm sure the mod is easy, but of course you need to be alert to avoid boiling the coolant !!
(**) - Re. engine revs spiking after start (1500 RPM), I REALLY DISLIKE it, you want to keep revs as low as poss. when an engine is cold, until the oil is moving. You can offset the behaviour to a degree by flipping transmission into "D" or "R" as soon as cranking is done - if you then return immediately to "N" or "P" the idle revs remain low and smooth (600-800) which shows the engine really doesn't NEED to be kept at high RPM while warming.
The above behaviours have been same on all my 4 x V8s, clearly deliberate engine ECU settings.
I have a fine pal has restored couple of Rolls Royce Silver Shadows, he's made serious fuel savings by replacing the belt-driven fan with a pair of electric fans; very easy to do.
14th Jul 2023 4:35 pm
L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
My D3 diesel roars on start up and it is the nature of the beast. The V8 is the same. I did drive a V8 LR3 in Texas , temp about 40C and the viscous fan was cutting in at very stop light making it very uncomfortably noisy to drive . The local dealer who I borrowed it from said they had many complaints about it. My Diesel D3 viscous fan, once started didnt ever cut in at all in the same conditions which impressed the dealer , who had never seen one, no end.
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