electric fan controller

[M1ke30]

going to order an electric fan controller for my M52 conversion..

ive got a could of questoins if someone fancies helping me out...

1st) is taking off the viscous fan permanently as easy as just taking it off the clutch?? or is there something else i should be doing..

2nd) what is the internal diameter off the cooling hose so i can order the correct insert.

3rd) what is the best hose for fitting the temp sensor to? top or bottom?

[ross_jsy]

Just go for a DanThe fan loom. Plugs into the stock fusebox and utilises a temp sensor in the radiator.

But yes, just whip off the viscous clutch

[GB69]

No need to go to that expense, just wire the fan to an ignition live via a relay so fan is on when ignition is on.

[M1ke30]

where would one acquire said loom? cost? and can you adjust the switch temp??

[ross_jsy]

Don't do what he said, it will overcool the car. There is a reason why fans aren't on all the time.

[ross_jsy]

where would one acquire said loom? cost? and can you adjust the switch temp??

PM a member called DanThe, he will tell you the cost.

You could by using different grade temperature switches but you just use an 88 degree (if I remember correctly) temp switch and it will run at the temperature BMW intended.

[M1ke30]

i wouldnt have done that anyways, but thanks for the input GB. LOL

[M1ke30]

where would one acquire said loom? cost? and can you adjust the switch temp??

PM a member called DanThe, he will tell you the cost.

You could by using different grade temperature switches but you just use an 88 degree (if I remember correctly) temp switch and it will run at the temperature BMW intended.

ya i've got a 88 stat waiting to go in, i also need to do the heater control valve. its started leaking, prompting this mini weekend project.

i'll send him a pm and see what he says

[GB69]

Don't do what he said, it will overcool the car. There is a reason why fans aren't on all the time.

Viscous is on all the time, cant overcool the car, thats why you have a thermostat. Will only cool, once thermostat opens.

[ross_jsy]

It's not on all the time. Hence the viscous part of the fan...

[GB69]

It's not on all the time. Hence the viscous part of the fan...

I've never known a viscous ever stop, its on all the time. It quickens up as engine speed rises.

[M1ke30]

the viscous fan does stop spinning, im sure at certain RPM's or something. not quite sure how it works. although it does defo stop.

[ross_jsy]

They will spin due to the small amount of internal friction in the viscous mechanism but won't be pulling any amount of air. You can stop it easily with a finger when the engine is cold. They kick in quite suddenly, you will hear a whoosh if the viscous is in good condition.

[M1ke30]

btw, this was the part i was going to order.....

thoughts??

http://www.ebay.co.uk/itm/Revotec-Adjus ... 338384e41f

[GB69]

btw, this was the part i was going to order.....

thoughts??

http://www.ebay.co.uk/itm/Revotec-Adjus ... 338384e41f

It'll work fine.

[ross_jsy]

It will work, just not the neatest solution in my opinion.

[Brianmoooore]

Positioned in the top hose, the fan will be on more than needed.
Positioned in the bottom hose, the fan won't come on quickly enough.
Correct position is about one third of the way down the radiator, so that it can detect when the radiator starts failing to reduce the coolant's temperature, where is, coincidently, BMW chose to put it.
An electric fan wired to be on all the time will be a ridiculous waste of both power and petrol.

[M1ke30]

i dont mind it that much. i'd just tuck all the excess wiring inside the light cover.

what about my original question, any idea on the diameter i'd need? i've read 32, 34 and 38 on different forums, just no idea what to get. and i'm gussing the top hose is the one i'd want to fit it to??

[jmc330i]

I bought a 38mm adaptor from revotec to fit a temp gauge sender in the top hose on mine. 35mm was the next size down, but way too loose.

[Brianmoooore]

i dont mind it that much. i'd just tuck all the excess wiring inside the light cover.

I think Ross was meaning "neatest solution" from an engineer's point of view, not for the aesthetics!

[ross_jsy]

Bingo Brian.

[M1ke30]

I bought a 38mm adaptor from revotec to fit a temp gauge sender in the top hose on mine. 35mm was the next size down, but way too loose.

superb, thanks man

[M1ke30]

Positioned in the top hose, the fan will be on more than needed.
Positioned in the bottom hose, the fan won't come on quickly enough.
Correct position is about one third of the way down the radiator, so that it can detect when the radiator starts failing to reduce the coolant's temperature, where is, coincidently, BMW chose to put it.
An electric fan wired to be on all the time will be a ridiculous waste of both power and petrol.

i'd never run a fan constant. thats just nuts.

but assuming i did fit it to the top or bottom hose surely with an adjustable temp switch for the fan i'd be able to fine tune when it came on to compensate???

[jmc330i]

Yes you probably could fine tune it, but it seems pointless when BMW can provide you with a temp sensor that's correct to begin with.

The only reason I'd go with hose mounted sensor is if the rad I was using didn't have the boss to fit the sensor.

[Brianmoooore]

If the sensor is fitted in the top hose, it will be exposed to hot coolant as soon as the engine thermostat opens, and this coolant will be at the operating temp. of the engine.
If you set the fan thermostat to switch at this temperature, then, as long as the car is moving at speed, the fan will run unnecessarily, since the water would have been cooled by the airflow through the radiator anyway. If you increase the switching temperature of the fan 'stat, then the engine will need to overheat before it will switch on, and the water may still have been adequately by the movement of the car.
Fitting the fan 'stat in the lower hose would avoid the problem of the fan switching on when not needed, but by the time the coolant here reaches anywhere near the engine operating temp., the engine would be close to or actually beginning to overheat, and with the lag before the fan does its job, would almost certainly go above the correct temp.
With the fan stat. fitted where BMW decided, the switching temperature can be just below the engine operating temp, so that it switches on when the temperature drop across the top one third of the radiator becomes just a few degrees, indicating that the airflow through the rad. has become inadequate, and needs electric powered assistance.
By the time the coolant that switched the fan 'stat reaches the bottom of the radiator, it will have been cooled sufficiently by the fan for the engine 'stat to be able to blend it with the water in the block and maintain the engine operating temp. without any overheating.

[Motorhole]

Positioned in the top hose, the fan will be on more than needed.
Positioned in the bottom hose, the fan won't come on quickly enough.
Correct position is about one third of the way down the radiator, so that it can detect when the radiator starts failing to reduce the coolant's temperature, where is, coincidently, BMW chose to put it.
An electric fan wired to be on all the time will be a ridiculous waste of both power and petrol.

And if it's in front of the rad will potentially hinder airflow when the car is moving and the fan doesn't need to be on.

[Demlotcrew]

All the modern E46 turds have the fan temp switch on the outlet (lower hose), but the fan is also controlled by the ECU so takes the temp reading from the head and works out a mean.

Ive fitted a switch to the bottom rad hose on an S54 build and it was perfect! 88º

Andrew

[DanThe]

The only benefit of a lower situated temp switch is if the system develops a leak the fan will still come on when the level of coolant in the rad drops

[Quaser]

sorry to thread hijack, but could someone pls tell me the part number for the twin fan switch that's needed

thanks

[Demlotcrew]

The only benefit of a lower situated temp switch is if the system develops a leak the fan will still come on when the level of coolant in the rad drops

I think it also offers a better way to limit the temperature swings. Yes the fan kicks in more often, but on average it will be on for less.

Having the cooling system fail and the fan still functioning is a brilliant precaution to have

[DanThe]

The only benefit of a lower situated temp switch is if the system develops a leak the fan will still come on when the level of coolant in the rad drops

I think it also offers a better way to limit the temperature swings. Yes the fan kicks in more often, but on average it will be on for less.

Having the cooling system fail and the fan still functioning is a brilliant precaution to have

If there is still coolant in the radiator do you not agree it would be beneficial to be able to cool it?

[Demlotcrew]

No absolutely, I think its a must!!!!!! Sorry, could have worded my reply better.

[DanThe]

Ahh,,,, I thought you were being a sarcy cooont

[Demlotcrew]

lol.