fan coincidence

Brian Smith · Post by **Brian Smith** » Sun May 03, 2009 9:04 pm

I've made a small discovery that I need to flesh out with more fact finding, but the quick synopsis is this:
The aux. cooling fan for an e12 has the same diameter and mounting hole locations as the aux. cooling fan for a Volvo 740, but the Volvo fan is significantly lighter, has more blades, and blows enough air to cool the car at idle from 3/4 on the gauge back to normal temps (1/4 on my gauge with coolest thermostat) without the help of a mechanical fan.

When my old fan motor died, I happened to have the Volvo fan lying about, and wondered how much effort it would take to mount it onto the e12.... The effort was solely in drilling 2 new holes to mount the ballast resistor for 2-speed operation.

A handy coincidence in my case!

Mike W. · Post by **Mike W.** » Sun May 03, 2009 10:02 pm

Interesting, most of the euro aux fans I've seen seem to be about the same as E21 fans, but often with a full cage on the front. That's an 11 blade fan, but with little pitch and much smaller than the stock 528i fan. How much pitch (bite of air) does the Volvo fan have?

I can't remember what I have in mine right now, it might be an e34, or it might be an E36. A couple of generations newer.

Brian Smith · Post by **Brian Smith** » Mon May 04, 2009 5:48 pm

Mike W. wrote:Interesting, most of the euro aux fans I've seen seem to be about the same as E21 fans, but often with a full cage on the front. That's an 11 blade fan, but with little pitch and much smaller than the stock 528i fan. How much pitch (bite of air) does the Volvo fan have?

I can't remember what I have in mine right now, it might be an e34, or it might be an E36. A couple of generations newer.

Mike, what I know for sure so far is this:
It is a 7-Blade Volvo fan.
The surronding "enclosure" for the fan is plastic instead of metal, as is the rest of the fan itself, hence the weight savings.
My plan is to trigger it on at 2 speeds using 2 radiator mounted switches of lower than stock temperature.
Mike, I also have an e28 radiator in the car, so I suppose that it's possible that a system with this relatively weak electric fan would not be feasible with a stock-type e12 radiator.
For me, it's still early "beta-testing" with this cooling system arrangement.
At this point, I'd confidently recommend it to someone who is having problems with temperature creep only when at slow speeds with the A/C on who also knew that there stock aux. fan was switching on but just not doing the job. Or perhaps for someone who is dissatisfied with the high noise level of the stock fan on high speed. This Volvo fan is much quieter than the stock unit.

More info as I encounter it...

-Brian