fan swap

[nero279]

has anyone used the fans from the underslung air-con unit to replace the main rad-fan?

I have two redundant electric fans from when i removed the air con, and now a shot viscous coupling or clutch or somethin, so thoughts are coming into my head.

Would i need to seal over the old viscous coupling? and any ideas on wiring and mounting would be useful.

I was thinking of using a sheet steel template to move the shroud mountings to the right place for the new fans, could also bend over the top of the rad and put mountings through the front lip on the engine bay.

As far as the electrics go, i've got a reasonable knowledge of electrics however, i'm not sure about this one, i'm guessin i'm going to need to install one if not two thermostatic switches, to turn the fans on and off as required. Or is there another way?

Any thoughts?

[BUSHWHACKER]

I took my viscous fan off, took out the middle plate where the oil goes, flipped the blade part over and fitted the two halves back together using three or four 8mm bolts with threadlock on them so it's permanently locked. Been like that for about 12 months now, never had any over heating problems.


Some pics here..http://hiluxsurf.co.uk/forums/showth...ht=viscous+fan

[The Lovely Boyo]

has anyone used the fans from the underslung air-con unit to replace the main rad-fan?

Any thoughts?

Hello,

The area of the two aircon fans is less than the area of the rad fan. The rad fan also has a far deeper and more aggressive blade angle so the flow rate would be considerably higher than the aircon fans. I don't think the aircon fans would blow much past the block etc.

An advantage of electric fans is being able to turn them off if you go through very deep water. How often do you take your truck wading?

I think Vince's idea is best if you don't want to spend money on new viscous oil.

[nero279]

An advantage of electric fans is being able to turn them off if you go through very deep water. How often do you take your truck wading?

that's the exact reason i don't want to lock it out. At the moment i'm not doing any deep wading, but as soon as the truck let's me save for a month or two without somethin goin wrong i'll be after a snorkel and winch.

I see what you mean about the blade angle, the overall area though looks to be not a lot different. Don't electric fans normally spin faster? so would this offset the difference in blade angle?


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the overall area though looks to be not a lot different.
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OK retract that i just looked, the fans are a lot smaller,

[kitesurf_phil]

I saw Tonys electric fan mod on the 1st Gen and was quite impressed.

Locking the viscous fan saps a few horses, whereas having an electric fan frees a few horses up. My only tip is to use good relays. I spent an afternoon with my nephew recently trying to work out why his electric fans on his Saxo had stopped working. The terminals on the relays had totally corroded away. Mind you, why Citroen put them just behind the front valance, where they get all the salt spray off the road, gawd only knows.

[The Lovely Boyo]

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OK retract that i just looked, the fans are a lot smaller,

If you do the maths (pi x (r x r)) the big fan is only a bit bigger than both of the small fans added together.

The big difference will be flow rate due to the blades.

Don't know about speeds of air con fans. Reconnect them and see - when I took my aircon off I left the plug on the engine wiring loom (in case i want to do just what you're suggesting)!

Someone on here has it wired so they can over ride and switch the fans off if they are in water, coz I supose overtemp won't be an issue LMAO

[MattF]

Did nobody let me know about this thread so that I wouldn't post an answer?

I'll do a more indepth response later. One quick question. How much control
are you wanting over the fan? Manual + thermostatic + override killswitch?

[BUSHWHACKER]

Did nobody let me know about this thread so that I wouldn't post an answer?

I'll do a more indepth response later. One quick question. How much control
are you wanting over the fan? Manual + thermostatic + override killswitch?

Oh no! you found this thread. I sense another 30 pages on the way!

[MattF]

Oh no! you found this thread. I sense another 30 pages on the way!

I aim to please. Just when you thought you were safe.

You have quite a bit of variation as to what you can do with the fan system.
As Vince has already mentioned, locking the viscous fan works lovely, giving
a constant flow of air without worrying about the fluid disappearing gradually
over time and causing the fan to become less efficient. A locked viscous fan
also make a lovely beast of a sound.

With regards to electric setups, you have to remember several minor points.
The main one is that an electric setup will never be as reliable as a mechanical
setup. There are far more points of failure. An electric fan also draws a fair bit
of current, so you need to make sure you're cable is sufficient.

With regards to the types of electric fans to use, firstly you have the option
of whether to use a fan that sucks or blows air through the rad. Drawing air
through the rad is more efficient than blowing air through it, so a sucking fan
of the exact same dimensions as a blowing fan will be better for cooling.
Secondly is the size of fan to use, and what blade type. Using an electric
fan of roughly the same fan width as the viscous fan will be adequate for
the job. Going much bigger won't make a vast amount of difference. The
auxilliary fan sits in front of the rad on the drivers side, so restricts air flow
through that part of the rad anyhow. With blade type, you can get the
straight blade types, (like the existing fan), staggered blade fans, (which
reduce the noise/resonance of the fan), and curved blades, which do the
same. It's pretty much a case of whichever takes your fancy. Never
noticed much difference between the different types regarding throughput.

When you mount the fan, provided you've got above 3/4 inch clearance
between the fan body and the water pump centre spindle, you should also
be fine for clearance. With the shroud, again, it's a theoretical point rather
than actual. No one has ever been able to determine for definite, (as far as
I know), whether a shroud that completely covers the rad is anymore
efficient than one that only partially covers it. Provided you concentrate on
cooling the top inlet side of the rad and then as much more of the rad as
possible, again, you should be fine. The shroud is merely to stop the fan
recirculating warmer air from the engine bay, so just make sure your opening
on the rear of the shroud is as closely matched to the blade width as possible.

Electrics wise, the kill switch is to stop the fan during water/mud crossings,
as the blades will literally act like a propellor, and try to drag themselves
towards the rad. With the temp switch, there's a spare mounting hole in the
bottom of the 'stat housing. Corolla switches are a nice one to use, as they,
(not 100% sure, but have yet to be told otherwise), appear to have a rating
of 90 degrees. Keeping the cooling around the 'stat temperature seems to
work best. Overcooling can lead to coolant not being dragged back in from
the expansion tank correctly, and also excessive wear and poor fuel economy,
whereas overheating drawbacks are obvious. You can also easily get the
Corolla switches from scr@pyards, so you can get one and spares for under
a tenner. They also use the same connector as the one already in the Surf
for the aux fan.

I've also attached a rough schematic for a switch/relay setup. Uses two
normally closed relays, and one changeover relay. Direct feeds from the
battery rather than the ignition so that the fan control can still be used
when the ignition is off. The low current feed only feeds the relay coils, so
would only need a small current fuse. Draw on that feed would be well under
one amp. The high current feed would need a time delay/slow blow/anti-surge
fuse, as the fan motors have a fairly high inrush current.

If I've missed anything, let me know.

[BUSHWHACKER]

Jesus christ in a Nissan Sunny.....I didn't mean 30 pages in one post!!!


I am impressed however.

[MattF]

Jesus christ in a Nissan Sunny.....I didn't mean 30 pages in one post!!!

I am impressed however.

It's nice to know all the months, blood and tears figuring that lot out
weren't in vain. Plus, your one of the contributors for the info in the
post above.

[Vagrant No2]

I copied Tony's twin fan set up but with a 3 position switch and a adjustable thermo switch . Also got warning lights wirred into set up so I know what the fan is doing .

[nero279]

Did nobody let me know about this thread so that I wouldn't post an answer?

I'll do a more indepth response later. One quick question. How much control
are you wanting over the fan? Manual + thermostatic + override killswitch?

Not too worried about turning them on manually, but an override/killswitch would be good for wading, with a warning light/buzzer in the cab. and obviously the thermostatic switch to control them under normal driving. I suppose a manual control to turn them on could be useful when towing etc. but like i say i'm not too worried, at the moment the trailers i'm towing are relatively light, so it depends on how complex it makes the wiring.

Having looked round the internet today i've seen a lot of twin fan units with adjustable thermostatic control switches already wired in, most of these seem to be designed for range rover P38's and some for jag's, a few going cheap on fleabay. And appear a good option if thet fit between the rad and pulleys.

Another option would be a visit to the sc rap yard, and pilfer an electric fan from a vehicle with similar sized rad. Maybe a paj (assuming they use electric fans), or a large estate - thinking a volvo / vauxhall carlton. The only problem then is mounting. but i should be able to knock somethin up.

[nero279]

I copied Tony's twin fan set up but with a 3 position switch and a adjustable thermo switch . Also got warning lights wirred into set up so I know what the fan is doing .

What fans did you use? were they relatively easy to fit? And what did you do with the redundant viscous coupling? Plate over it? Leave part of it there? This is the bit that's worrying me most. Should i be worried?

[MattF]

If all the Jag ones are similiar, forget those. The twin diagonally spaced fans
in the square shroud are at the opposite points where they would be best suited. Plus, if I remember correctly, the shroud is too deep.