electric fan install

[Zenkiowns]

holy old thread bat man.

Ah, that was before I realized my gauge was faulty. lol

[flyboyx]

yes, this is an old thread. here was my solution. i used the factory bmw electric fan out of a 750i. since these cars are pretty tough to come by, you can also use the fan out of a 740i from the early 90's (ish). don't get the fan that includes its own shroud. that one will not fit.

i finished up my cooling fan and took a few photos in the event someone else would like to use the same system. since the 750iL fan is about 3 or 4 inches larger in diameter, the condenser brackets had to be changed to make it work. i cut the bracket off the top of the condenser and welded it to a reshaped lower bracket on the passenger side of the car.


my solution to make this fan fit was to rotate it about 60 degrees clockwise. that puts the upper right mount at the 360 degree position. i cut out some of the metal on the bottom of the upper core support because the diameter of the fan is too large to fit in the core support opening. this also gave me a good solid place to mount the top bolt.





the third mount was a little more complicated. i had to fabricate a bracket to secure it properly to the condenser. i folded the original mounting point flat and bolted the top part of my fabricated bracket to that point. i welded to the bottom condenser mount but that probably wasn't necessary. two #8 bolts would have worked if you don't have access to a welder.



here is a pic with the fan installed. it pretty much takes up the opening in the core support plus another inch.



this is a closeup of the top of the fan installed in the opening i cut in the underside of the upper core support



finally, the wiring pigtail on the 750i fan is really short. my solution was to cut the pigtail off my old fan and also about a foot and a half of the wiring from one my parts cars. they are spliced together under the black plastic sheath.



for me, this solution was a lot cheaper than the spal that most everyone uses. from an electrical standpoint, i think it is a better choice because it is a factory part that you can just extend the wiring and plug in. also, like the e30 fan, it comes with the three wire design with resistor so you get two speeds just like a factory fan. i have not run it yet to test it, but i think it will do a good job of keeping my engine cool. it may also allow me to use my m42 radiator so i can eliminate the reservoir on my driver side fender well.

this morning before i started my trip, i tested out the aux fan circuit. to do this, i turned on the ignition and jumper-ed the circuit at the three prong radiator switch. low speed worked great, but high speed blew the fuse. after cross referencing, i found the number three fuse that i blew is actually for low speed. it turns out that the high and low wires in the 750i fan are in opposite positions compared to the e30. good news with this plug: it can be taken apart very easily. all you have to do is slide the tie wrap off the connector, open up the plastic retainer, and swap terminals to the correct position. when the high speed circuit is connected, that thing will really blow some serious air! now that it is tested and i know it works, i feel really confident that all of my cooling issues are taken care of.

[hella 325]

nice, I can't see why this wouldn't work beautifully.

[Bejbis]

does it help throttle response any?

[roarange808]

Do not wire it up to ur auxilery fan. I did this n it's a bad idea. It will work for a while but then the auxillery fan has a resister. Wiring up another fan will cause it to over heat and cease to work. Meaning now the high speed does not kick in. It's better to do it the right way or better of to just wire it up to a switch.

[antil33t]

It has the resistor for the "low" speed mode, it has another power line that doesn't use the resistor. What overheats? the resistor?

[ss45466]

For those interested I found the P/N for the lower temp thermo switch. I had to search for a while to find. Thought it would be helpful here. List cost on it is $33.00

80/88 deg P/N: 61 31 8 361 787