E36 - viscous radiator fan vs electric fan

[Ahmedsinc 414]

Thinking about ditching the viscous coupling setup on Pigpen in favour of a 14" electric item. Front end is entirely off the car presently as the old iron block appears to have cracked a coolant gallery as there's mayo in the sump but nowhere else. Not massive quantities but enough to convince me it's a good time to replace the engine. Replacing with an alloy block in the interests of losing weight, have removed all the A/C plumbing and heat exchanger as well as it's never worked and I really can't be bothered with fixing it.

Will reinstate the front pusher fan with some new brackets up front, but wondering if I can use another pusher fan reversed on the engine side of the radiator or should I use an aftermarket item? Also wondering what temperature the stock switch kicks in at to start the pusher fan, anybody know? And more importantly, where to find a lower temp one?

Chur!!

[Ahmedsinc 414]

Should probably add that I'm not necessarily looking for a hp increase, I can't see it would be much more than 1-2hp at the most. Thinking more along the lines of ease of access and reliability.

Also, will the extra airflow from not having anything obstructing the radiator counter the need for a fan? Car doesn't see stop start traffic anymore, only open road driving.

[Michael. 2313]

I don't really rate generic electric fans for radiator cooling, they seem to me more of an aux back up or for smaller oil coolers.

From what I've noticed the usual ex China generic car fan kits are fair basic in design with a low blade pitch and pretty noisy.

Not sure of the stats, but I get the impression they are pretty taxing on electrical power too, putting a fair bit of load on the alternator. So it's not like you free up parasitic power by using one.

Alternatively, what is really wrong with the viscous clutch fan? They regulate speed smoothly only when temperatures get high and freewheel most of the time putting little load on the engine, especially at highway speeds. The blades are bigger and have a greater pitch so will flow more air easily too.

[Ahmedsinc 414]

The gain from eliminating parasitic loss from a viscous fan would have to be pretty minimal I reckon, 1-2hp would be the max gain at a guess, certainly not enough to be noticed.

Nothing really wrong with the standard viscous setup, just noticed the one I have is putting up very little resistance and will probably need replacing when the new donk goes in. Hence pondering getting another pusher fan and reversing the blade orientation & motor polarity so it acts as a puller. The cheaper kits available on trade do look fairly token as far as the fans go, but I assume a higher quality setup would work equally well as a viscous, if not better.

[Ahmedsinc 414]

Have done a little digging around the internets and found Hybrids S50B32 / M325i build thread over on r3vlimited http://www.r3vlimited.com/board/showthread.php?t=162982.

Strangely I can't find the original here or via google, is this a symptom of the server change?

Anyways, turns out he used a standard E36 pusher fan mounted in front of the Fluidyne (mmmmm, Fluidyne) radiator. At the moment I'm guessing if one of those fans can cool a B32 then it'll probably do the same for my old hack.

Spot quiz: anyone know what thread pitch and diameter the M42 thermo switch uses? Seems the 318i used an 80* / 88* thermo switch instead of the 91* / 99* unit used on the M50.

[Forrest 35]

Have done a little digging around the internets and found Hybrids S50B32 / M325i build thread over on r3vlimited http://www.r3vlimited.com/board/showthread.php?t=162982.

Strangely I can't find the original here or via google, is this a symptom of the server change?

Anyways, turns out he used a standard E36 pusher fan mounted in front of the Fluidyne (mmmmm, Fluidyne) radiator. At the moment I'm guessing if one of those fans can cool a B32 then it'll probably do the same for my old hack.

Spot quiz: anyone know what thread pitch and diameter the M42 thermo switch uses? Seems the 318i used an 80* / 88* thermo switch instead of the 91* / 99* unit used on the M50.

M42 thermo sensor thread and pitch is identical to the M50 one. I am running an 14 inch electric fan (high speed) with a 318i 80/88c sensor set up in mine, with the original aux fan (low speed), being a track car I have gone for overkill. Make sure you buy a new switch, and go to pick a part and cut the female plug off one with some wiring (the M50 temp sensor has a different style of plug which won't connect unless you bodge it).

I also got a lower temp thermostat to match this

Edited July 20, 2015 by Brams

[Ahmedsinc 414]

M42 thermo sensor thread and pitch is identical to the M50 one. I am running an 14 inch electric fan (high speed) with a 318i 80/88c sensor set up in mine, with the original aux fan (low speed), being a track car I have gone for overkill. Make sure you buy a new switch, and go to pick a part and cut the female plug off one with some wiring (the M50 temp sensor has a different style of plug which won't connect unless you bodge it).

I also got a lower temp thermostat to match this

Legend! Cheers for the data mate