viscous-vs-electric fans

[leyland]

hello all, today i removed the two 12 inch electric fans from my 1983 3.5 v8 with carbies, i replaced them with the original viscous fan. i had overheating problems when driving slow in low range and on warm or hot days, driving on the freeways was fine.now with the viscous fan the engine runs so cool that i think theres something wrong with temperature gauge. i can touch the top radiator hose without burning where as before i couldnt. i will replace the temperature sender anyway.
from peter.

[V8Landy]

My 3.9 d1 ran a little high with thermos and over heated when towing put the viscous back on and no probs i vote the viscous is the way to go.;)

[Slunnie]

Viscous fans have a lot lot more HP behind them than electric fans.

[350RRC]

My 3.9 d1 ran a little high with thermos and over heated when towing put the viscous back on and no probs i vote the viscous is the way to go.;)

Politely suggesting something wrong with the set up.

I'm running a 400,000 km old Chev on gas behind a stock 3.5 RRC rad and have no probs with a fake EL twin thermo set up. If anything it runs too cool at times.

Really depends on where the switching is getting the signal from and at what temp.

cheers, DL

[Offender90]

Go the viscous fan. To quote Slunnie, theres a lot more HP behind visous fans.
I thought about going electric with my 3.9V8, but after research definately staying with viscous.

Cheers

[mike 90 RR]

e runs so cool that i think theres something wrong with temperature gauge. i can touch the top radiator hose without burning where as before i couldnt. i will replace the temperature sender anyway.


Might be that you have no Thermostat .... As usually they get removed in an attempt to keep it cool, when the radiator is blocked // Get it removed & rodded before Summer arrives

Electric fans are just that ... Folks are either "Fan" of em ... Others are not
You need to set them up right, to get the best out of them, which involves more than just bolting them in

Mike
:)

[V8Landy]

Politely suggesting something wrong with the set up.

I'm running a 400,000 km old Chev on gas behind a stock 3.5 RRC rad and have no probs with a fake EL twin thermo set up. If anything it runs too cool at times.

Really depends on where the switching is getting the signal from and at what temp.

cheers, DL

It was set up properly. I had the radiator roded cleaned ect no diff. Maybe some sort of prob elsewhere but it is fine the way it is so will not worry about it.:)

[Yorkshire_Jon]

This old chestnut of a question will never go away - opinion is simply too greatly divided!!

Personally, I would (and do) always go viscous. Much more reliable and the viscous bit is fixable with a pair of the mrs' tights if need be!

I know the physics behind the increase power useage of viscous - but in reality its negligable on a 2.5t brick on wheels!

Viscous all the way!!

Jon

[LandyAndy]

The only real advantage with the electric fans is you can easily make sure they are off for a water crossing and they wont destroy a radiator with the fan corkscrewing into it.
I prefer the viscous hub.
Andrew

[Psimpson7]

I'd go viscous every time. They move massivley more air that an equivalent sized electric one.

[LOVEMYRANGIE]

I'd go viscous every time. They move massivley more air that an equivalent sized electric one.

Not necessarily. The problems with mechanical fans is they rely on engine speed. Slow running, low engine speed means low fan speed. I havent had one issue with overheating in the 4 years they have been on. Crawling in peak hour traffic with twin thermos running pumps a lot more air than in idling engine fan I'm afraid.
The mistake everyone makes is bad fan selection. Davies Craig fans are absolute rubbish and performance wise are very poor indeed. A lot of people have had success with the Falcon fans but I custom made mine using 13" SPAL fans. Each fan pulls 2000+ cu.ft/m thru a 40mm core.

I can stand on the loud pedal with the A/C on and it actually gets up and goes and stays nice and cold inside!!!
Nope, I like my thermos, never look back.

Cheers

Andrew.

[350RRC]

Not necessarily. The problems with mechanical fans is they rely on engine speed. Slow running, low engine speed means low fan speed. I havent had one issue with overheating in the 4 years they have been on. Crawling in peak hour traffic with twin thermos running pumps a lot more air than in idling engine fan I'm afraid.
The mistake everyone makes is bad fan selection. Davies Craig fans are absolute rubbish and performance wise are very poor indeed. A lot of people have had success with the Falcon fans but I custom made mine using 13" SPAL fans. Each fan pulls 2000+ cu.ft/m thru a 40mm core.


Agree totally with this ^^^^^^. Low speed crawling with twin thermos has it all over a single engine driven fan. At highway speeds the pros and cons of either set up becomes largely irrelevant.

Have no idea what the ELs flow on mine, but its truckloads more than the original fan on the water pump. At idle there is absolutely no comparison.

The efficiency of the shrouding comes into play as well. Two fans are directly pulling air through a more widely spread and 'larger' area of the radiator, instead of a smaller area in the centre.

Flame away. :D

cheers, DL

[Dougal]

Not necessarily. The problems with mechanical fans is they rely on engine speed. Slow running, low engine speed means low fan speed. I havent had one issue with overheating in the 4 years they have been on. Crawling in peak hour traffic with twin thermos running pumps a lot more air than in idling engine fan I'm afraid.
The mistake everyone makes is bad fan selection. Davies Craig fans are absolute rubbish and performance wise are very poor indeed. A lot of people have had success with the Falcon fans but I custom made mine using 13" SPAL fans. Each fan pulls 2000+ cu.ft/m thru a 40mm core.

I can stand on the loud pedal with the A/C on and it actually gets up and goes and stays nice and cold inside!!!
Nope, I like my thermos, never look back.

Cheers

Andrew.

I agree with this too.
The "generic aftermarket fans" are crap. Especially the "multi-fit, can push or pull no shroud needed" types.

I run two corona fans with integral shrounds on my rangie radiator and they fit excellently. Only a small extension to the shrouds around the side was necessary to keep the air moving in the right direction.
Of course with a nice efficient diesel they don't run much. But when needed they shift a lot of air regardless of engine speed.

[streaky]

This old chestnut of a question will never go away - opinion is simply too greatly divided!!

Personally, I would (and do) always go viscous. Much more reliable and the viscous bit is fixable with a pair of the mrs' tights if need be!

I know the physics behind the increase power useage of viscous - but in reality its negligable on a 2.5t brick on wheels!

Viscous all the way!!

Jon

Hi Jon.

I agree with your choice of viscous fan and was able to add a bit of data to this debate a few weeks ago when we had my Discovery on a rolling road Dyno.
The Viscous fan stole 15hp from the wheels when it kicked in. I was quite surprsied...but I won't be changing it for an electric one either.

S

[LOVEMYRANGIE]

Funny thing is, viscous fan some love, but viscous transfer, they hate.....;)

For those of you that love the fan, I have a spare for sale :D

Message - AULRO Classifieds (http://www.aulro.com/apc/showproduct.php/product/1681/cat/500)

Cheers

Andrew.

[d2dave]

The only real advantage with the electric fans is you can easily make sure they are off for a water crossing and they wont destroy a radiator with the fan corkscrewing into it.
I prefer the viscous hub.
Andrew

This post has reminded me of something that I have pondered for years.

When doing deep river crossings it is advisable to remove fan belt.

I have often thought of making some thing to lock the fan from turning but I am not sure whether this would do any damage to the viscous hub.

Does anyone know?

Dave.

[mike 90 RR]

When doing deep river crossings it is advisable to remove fan belt.

This is not a Hot idea as you also stop the coolant flow, moving around the block & heads



I have often thought of making some thing to lock the fan from turning but I am not sure whether this would do any damage to the viscous hub.


This is also not a Hot idea ... cause if the Temp rises while on dry ground ... then the viscous will "lock up" while "being locked up"

If you want to stop the fan for a water crossing ... Remove it, before crossing

Mike
:)

[LOVEMYRANGIE]

This is not a Hot idea as you also stop the coolant flow, moving around the block & heads



This is also not a Hot idea ... cause if the Temp rises while on dry ground ... then the viscous will "lock up" while "being locked up"

If you want to stop the fan for a water crossing ... Remove it, before crossing

Mike
:)

Or use thermo fans with a lockout switch..... :cool:

[Dougal]

Or use thermo fans with a lockout switch..... :cool:

Electric fans aren't going to eat the radiator anyway. No need for a lockout switch IMO.

[mike 90 RR]

Electric fans aren't going to eat the radiator anyway. No need for a lockout switch IMO.

... You want the "lock out switch" to prevent them coming on, if water shorts out the relays (or what ever) when crossing / water splashing about the engine bay ...

You don't want em to turn on, when submerged and pulling water /// (Pull the main fuse prior, would be the go)

Mike
:)

[Dougal]

... You want the "lock out switch" to prevent them coming on, if water shorts out the relays (or what ever) when crossing / water splashing about the engine bay ...

You don't want em to turn on, when submerged and pulling water /// (Pull the main fuse prior, would be the go)

Mike
:)

I run a diesel, so water splashing doesn't scare me much. You guys with spark plugs, I can smell the fear already.:D

[mike 90 RR]

I run a diesel, so water splashing doesn't scare me much.

You may have missed my point ... You don't want the fans to work when submerged because "Electricity & water don't mix" :eek:



You guys with spark plugs, I can smell the fear already.:D

.... I'll put more "underarm spray" on :p

Mike
:)

[Dougal]

You may have missed my point ... You don't want the fans to work when submerged because "Electricity & water don't mix" :eek:

It's 12v. You can put your tongue on that.

[mike 90 RR]

It's 12v. You can put your tongue on that.


You can also ark weld with it too :twisted:

https://www.aulro.com/afvb/

Mike

[Dougal]

You can also ark weld with it too :twisted:

http://publius.mu.nu/archives/welding-thumb.jpg

Mike

Yes but you can't arc weld with water. You can however arc-weld under water. Showing that water has enough conductivity to screw with electronics, but not enough to electrocute you because your fan motors got wet.

YouTube - Underwater Welding

[Crackerjack]

I think that if you are having overheating problems with electric fans you have a poor installation or faulty cooling system, first you need proper fans designed for the job, not some rubbish from a scrap yard that used to be in a Toyota Corolla, then it needs to be fitted well and controlled by a good thermostat.
I have fitted twin Kenlowe fans to my V8 discovery with a non Kenlowe (far superior) inline adjustable thermostat with all the relays sealed in a box and everything running heavy wire, even on a warm day I can't get the things to come on, they were fitted on a new radiator.
You have to look at your cooling system as a complete package, if you are overheating you need to investigate why, there are many reasons why you could overheat.
If you are off roading the viscous fan isn't going to do much until it locks up, steals your power and drowns out all conversation in the area, on the freeway the fan isn't needed but is still turning with your engine.
This comment isn't a reflection of any equipment used by members in this thread but I feel that you are turning your back on a very good piece of kit which if used properly does a very good job.

[djam1]

I think that if you are having overheating problems with electric fans you have a poor installation or faulty cooling system, first you need proper fans designed for the job, not some rubbish from a scrap yard that used to be in a Toyota Corolla, then it needs to be fitted well and controlled by a good thermostat.
I have fitted twin Kenlowe fans to my V8 discovery with a non Kenlowe (far superior) inline adjustable thermostat with all the relays sealed in a box and everything running heavy wire, even on a warm day I can't get the things to come on, they were fitted on a new radiator.
You have to look at your cooling system as a complete package, if you are overheating you need to investigate why, there are many reasons why you could overheat.
If you are off roading the viscous fan isn't going to do much until it locks up, steals your power and drowns out all conversation in the area, on the freeway the fan isn't needed but is still turning with your engine.
This comment isn't a reflection of any equipment used by members in this thread but I feel that you are turning your back on a very good piece of kit which if used properly does a very good job.

Whats a warm day though

[Crackerjack]

We actually were able to take our jumpers off a couple of weeks ago :lol2:

But really, temps in the mid 20's

When I get the fans to come on they do pump a lot of air, (I have to fiddle with the adjustable thermostat to get them to come on)

[V8Landy]

I think that if you are having overheating problems with electric fans you have a poor installation or faulty cooling system, first you need proper fans designed for the job, not some rubbish from a scrap yard that used to be in a Toyota Corolla, then it needs to be fitted well and controlled by a good thermostat.
I have fitted twin Kenlowe fans to my V8 discovery with a non Kenlowe (far superior) inline adjustable thermostat with all the relays sealed in a box and everything running heavy wire, even on a warm day I can't get the things to come on, they were fitted on a new radiator.
You have to look at your cooling system as a complete package, if you are overheating you need to investigate why, there are many reasons why you could overheat.
If you are off roading the viscous fan isn't going to do much until it locks up, steals your power and drowns out all conversation in the area, on the freeway the fan isn't needed but is still turning with your engine.
This comment isn't a reflection of any equipment used by members in this thread but I feel that you are turning your back on a very good piece of kit which if used properly does a very good job.

I used el thermo's which are sworn by a lot of people to be the goods. I had mine checked by a well respected (in our community) Auto electrician.
I had no issues before i installed the elec fans and none while normal driving or 4wding but as soon as i put weight on the back up went the temp. I seriously suggest if you do any towing not to go elec fans as mine is fine when viscous is on but not elec.
As for the elec fans pushing more on idle as a viscouse i say bull****. just my opinion.

[d2dave]

This is not a Hot idea as you also stop the coolant flow, moving around the block & heads



This is also not a Hot idea ... cause if the Temp rises while on dry ground ... then the viscous will "lock up" while "being locked up"

If you want to stop the fan for a water crossing ... Remove it, before crossing

Mike
:)

This then answers my question.
I wasn't sure whether the viscous actually locked or when hot just worked harder.

Dave.

[350RRC]

I had no issues before i installed the elec fans and none while normal driving or 4wding but as soon as i put weight on the back up went the temp. I seriously suggest if you do any towing not to go elec fans as mine is fine when viscous is on but not elec.
As for the elec fans pushing more on idle as a viscouse i say bull****. just my opinion.

Don't know how you had them switched, but at highway speed it shouldn't make much difference between the two types, even when towing.

Mine has had one fan going all the time for 60k km and the second fan only comes on when the gauge gets to about 1/3. It will not go over 1/2 in Melb at multiple red traffic lights on a 35+C day with the 350 boat anchor idling away.

Maybe the electronic interference from Maccas drive thru in Colac was affecting yours?? :D :D

You're welcome to see how I've done this, I go through Colac a bit.

cheers, DL

[Dougal]

I think that if you are having overheating problems with electric fans you have a poor installation or faulty cooling system, first you need proper fans designed for the job, not some rubbish from a scrap yard that used to be in a Toyota Corolla,

You shot a big hole in your argument right there.
Toyota's fan suppliers have a lot more R&D into shifting air than any of the "aftermarket" suppliers ever will.;)

[Crackerjack]

You shot a big hole in your argument right there.
Toyota's fan suppliers have a lot more R&D into shifting air than any of the "aftermarket" suppliers ever will.;)

If you knew what I meant no I have not.
A, A fan from a scrapped car is likely to be past its best and,
B, a Toyota Corolla is a 1000kg car not a 2500kg 4WD

[Dougal]

If you knew what I meant no I have not.
A, A fan from a scrapped car is likely to be past its best and,
B, a Toyota Corolla is a 1000kg car not a 2500kg 4WD

I've been running two toyota corona fans (same as corolla fans) for the last 6 years.;)

Yes I got them from a car wrecker, they haven't missed a beat.
Fans aren't rated by vehicle weight either.

[d2dave]

I've been running two toyota corona fans (same as corolla fans) for the last 6 years.;)

Yes I got them from a car wrecker, they haven't missed a beat.
Fans aren't rated by vehicle weight either.

Correct. Fans are not rated by weight. They are rated by air flow or displacement.

However the bigger the vehicle the bigger the fan would be needed.

A pair of fans off a laser would not be suitable for SHMBO's Fairlane.

Dave.

[Dougal]

A pair of fans off a laser would not be suitable for SHMBO's Fairlane.

Dave.

A single fan which has to cool a 1.6L engine plus aircon and auto box would in a pair be about perfect for a 4 litre ford.
A V8 ford, possibly not.

[Crackerjack]

Dougal and Mr Whippy I think understand what I was on about, I am not critisizing a fan from any particular manufacturer but I am if you are fitting an unsuitable fan to a vehicle then complaning it does not do the job, if a suitable fan is fitted properly and the cooling system is in good condition then electric fans in most situations will do the job.

[LOVEMYRANGIE]

Electric fans aren't going to eat the radiator anyway. No need for a lockout switch IMO.Its more so that fans dont like being dumped in water and loaded up when running as the amp draw tends to rise rather fast and the fuses blow.

Water wont generally tend to be a problem getting sprayed around as it takes very little to stop them even when they are running flat out.

I dont have a lockout on mine, just a manual on and I just unplug a wire from the switch on the thermo housing to stop them when needed.

Have a look here http://www.pacet.co.uk/

Critical thing with fans is you want one that "pulls" not push, and look at the airflow figures. Anyone that doesn't state a figure through at least a 30mm core thickness, fans will be inadequate.
Was under the bonnet of SWMBO's '99 Lancer the other day poking around and taking some skin off my knuckles. The fans in these have an exceptional amount of flow, the A/C one in particular which is smaller, but has a far deeper pitch on the blade than the main fan and pulls significantly more air.
A lot of late model 4 & 6cyl passenger fans are more than adequate for the job, it just comes down to fitment and how many. The Lancer ones for example are separate from the shroud, but they mount to the shroud at the fan body, which then makes it hard to fit to any other shroud.
I couldnt source Pacet here but Factory Air were a supplier of mine so I scammed a good deal an made my own including the shroud.

Cheers

Andrew

[vnx205]

Don't know how you had them switched, but at highway speed it shouldn't make much difference between the two types, even when towing.
.. ... .. ... ..

cheers, DL
At highway speed, you don't need a fan at all. :) Years ago a mate of mine unbolted all the fan blades from his Peugeot 403 and left them off for a year or so. It got a bit warm when he went to visit his girlfriend in Sydney, but on the open road, it ran at exactly the same temperature as when the blades were on.

IIRC, his fuel economy improved by almost 2 miles per gallon.

[spudboy]

I wonder why no-one has developed an electrical clutch thingy like you get on your air conditioner, hooked up to a thermostat, for the main (engine driven) fan?

Seems like a reasonable idea to me. zero power drain when you don't need it. Full power once over 'x' degrees C. Can lock it out when doing water crossings......

[LOVEMYRANGIE]

I wonder why no-one has developed an electrical clutch thingy like you get on your air conditioner, hooked up to a thermostat, for the main (engine driven) fan?

Seems like a reasonable idea to me. zero power drain when you don't need it. Full power once over 'x' degrees C. Can lock it out when doing water crossings......

They have. A Horton Fan, but is air driven for use on trucks. Problem is when they lock in, they lock in. Theres no slow clutching effect so would be a little hard on components in a car with all that fan load instantaneously when engines at speed.

[Scouse]

I wonder why no-one has developed an electrical clutch thingy like you get on your air conditioner, hooked up to a thermostat, for the main (engine driven) fan?

Seems like a reasonable idea to me. zero power drain when you don't need it. Full power once over 'x' degrees C. Can lock it out when doing water crossings......Our 4cyl Centura had one of these so I'm sure other cars had them too.

[d2dave]

They have. A Horton Fan, but is air driven for use on trucks. Problem is when they lock in, they lock in. Theres no slow clutching effect so would be a little hard on components in a car with all that fan load instantaneously when engines at speed.

And when it comes on it sucks about 50 Hp, and usually comes on when lugging up a hill.
Just what you need, half way up a hill and all of a sudden you lose 50Hp.

Dave.