Viscous fan

[HARMEX]

Hi there

Does anybody know when the vicsous fan should be running. I have just changed my water pump because of a leak (2.7 Diesel Maverick 1997) and now the viscous fan seems to be running all the time (roaring fan noise above about 1500rpm). I thought it should only cut in when the engine is really hot. The old one only came in for the first half mile from start then cut out, but maybe it was worn out because the engine did get hot when towing in the summer and I never heard it cut in.
If the new one runs all the time even when cold does it mean my new pump assembly is duff. It is a pattern part (NIPPARTS) as the originals are so expensive.

Any help much appreciated

Cheers

Tim

[zippy656]

the fan should be on all the time, i belive your thinking of an electric fan that can turn on and off, but the vicsous in spinning all the time..


they are over cooled any way.. mine never gets about halfway. even when towing..

there is a thread on fitting an electric fan running now.. take a look if you can.

zippy

[Deleted Member S]

I had this prob with the 1st water pump I fitted it turned out to be a faulty viscous coupling so took it back off & got a replacement under warranty & it then then only roared for a short distance then went quiet

[tezzer]

yep, mine was the same, noisey for a minute or so and the quiet. :thumb2 :clap





tezzer

[Thomas-the-Terrano2]

the visous will appear to be on all the time but in fact is just dragging when motor
is cold. once warmed but not hot the viscous wil allow the fan to rest though
again it might gently drag then if 'stat kicks in will 'lock' the coupling and again
will run at engine speed. have seen the idle spin speed stopped by placing something
unimportant like a carrot there and the blades progress halted, the carrot unscathed
but wouldnt recommend using fingers.

think the starting roar is quite characteristic of these trucks' commercial heritage
and longlevity. some have fitted kenlowe electrics for improved warm up times
though and ability to turn off whilst fording.

[HARMEX]

Thanks for all the replies and advice. I think it seems strange because it is so different to the old fan. I will run it for a week or so and see how it goes. At the moment the fan seems locked in even when the engine is warmed up and the stat is open but the engine is only at normal operating temperature

Cheers !

Tim

[Thomas-the-Terrano2]

Thanks for all the replies and advice. I think it seems strange because it is so different to the old fan. I will run it for a week or so and see how it goes. At the moment the fan seems locked in even when the engine is warmed up and the stat is open but the engine is only at normal operating temperature

Cheers !

Tim


I await a techy jumping in here but whilat the fan should kick in with the stat it isnt
physically joined. instead theres a fluid coupling independent of the cooling system
that once 'feel's its too warm solidifies and start the fan spinning at crank speed
rather than just idling along after it.

i recall reading on the kenlowe site that whilst they said towing in uk was ok with
their system, mountain towing in mainland europe would recommend using original
set up ie viscous, thought sounded odd at time that they thought oem was better
in extreme conditions than there own and it was this comment that put me off the
(up)grade.

best members to ask would be muzz or davemud as both reguolarly tow to bottom
of euroland via mountain passes, sorry guys sure there are plenty others that have
done too but think certainly dm had elecy fans on terrano before getting patrol.

[DJ38]

Good point, I fitted a 16" on the rear and x2 9" electric fans to the front of my radiator on my 3.1 trooper. Had them controlled with a thermocouple stat fitted inside top pipe.
Worked perfectly in the UK.
I put them on to improve power and fuel economy. Did a lot of different trial and error setting them up.

But when towing caravan in France, found temperature would rise causing power loss when travelling up "false flats" never mind mountains.

Went last year and put viscous fan back on no problems, had more weight and four bikes on the roof.
I would have thought that the electric fans would have easily over cooled the engine but the viscous fan is better for heavy usage.
Maybe it cools all the time even when coasting.

[cssuk]

the viscous should be on for the first mile or so in fact at a fast idle you can hear it cut out after a couple of mins, this is as the silicone oil in the hub is thrown out to the edges and it loses drive, when it gets hot the bi-metalic strip on the front of the hub blocks or opens a valve within the hub and the fluid returns, this locks the fan solid and causes the roar, they dont last forever and the hub is usually avail on its own, as for why it works better thats simple ..its a huuuuuge fan and its got a 100+ hp motor behind it a kenlowe etc wont ever come close to a well setup viscous unit

[davemud]

hi u guys
I have fitted the new dual speed kenlowe fan to my patrol, removing the viscous.
The dual speed unit has adjustable thermostatic control for general running and high speed switch to take over when things get hot.
This works really well been on nearly a year and only ones having to fit my viscous back this was while touring in the south of France down to Spain.
<a href="http://s713.photobucket.com/albums/ww136/davemud1/Nissan%20Patrol%20Mods/?action=view&current=Kenlowe1.jpg" target="_blank"><img src="http://i713.photobucket.com/albums/ww136/davemud1/Nissan%20Patrol%20Mods/Kenlowe1.jpg" border="0" alt="Kenlowe fan unit"></a>

Advantages: Warms up much quicker, engine in quieter, better fuel economy, engine revs more freely
Disadvantage: Remember to leave the old viscous unit in the van ready to fit if needed, possible battery drain.

Plan to Fit LED in dash to show when the fan is running on thermal control to monitor, the switch has LED fitted to remind me to turn on when not needed.
May move up to dual 14" fans on the Patrol as they will fit across the rad, you have removed the standard cowling to fit either fan options.

[BIG-JOHN]

Hi there I also had a new water pump fitted and I also have the same problem the fan is running all the time it does not disengage as it should do, this was 3wks ago have been back to garage and I am having a new one fitted on warrenty which I hope will cure the noise and wind roar from the fan. My wifes T2 does not suffer this problem it cuts out after around 200 to 300 yards and appears to be working ok.........

Get it changed and try another one.

Regards john n wife................

[Jocky]

When the fan engages properlly, when the temp is high enough you'll know about it. If it don't you'll overheat if your towing.

If driving solo it should never get temp high enough to engage fully.

I liked the sound of mine roaring when engine was cold :D

I didn't like when towing across A66 up steep incline and it didn't come on:eek:

Nearly toasted ma engine:doh

[HARMEX]

Finally sorted !

After a big fuss from the shop I got a replacement part under warranty. I fitted it but it was exactly the same (fan engaged all the time) :(

Now I was really fed up, so I ordered a genuine Nissan part and fitted that (actually made by Pierburg). Did not take long to fit as after three attempts I was becoming an expert :D

Took the second part back to the shop and they (very reluctantly) gave me my money back. It was quite clear that they did not believe me. They said they had sold a few and had no other returns. I can only assume all the other customers were stone deaf !

I suppose the moral of this story is to be very cautious when buying pattern parts !!

Cheers - Tim.