Transmission Cooler Fan Wiring Tip - 2009 e93 335i.

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matreyia

Captain
Apr 19, 2017
1,312
I examined the splash patterns of both wheels and saw that all debris and liquids always fling towards the rear of the car and never inside the front inner fender. Therfore I faced the vents upward to assist in hot air escape. Because there is no danger of anything getting flung into the up oriented vent slits.
 

matreyia

Captain
Apr 19, 2017
1,312
Good info! I will also be retrofitting an oil cooler to my PD transmission, once it arrives to Hawaii. I am currently looking at Setrab series 1, 19 row cooler (with 342cfm fan).. I plan to use the ducting in my 1m front bumper for the cooler, will fab my own brackets etc.. Ill be using the improved racing 165* high flow trans thermostat. I have the VS fittings and plan to find a compatible switch.
What are you guys using for the switch to turn on the fan? Not the wiring location, but the actual switch/sensor? and what temp is optimal for the fan to engage?
The fan should come with a wiring diagram and relay terminal to hook up to a thermostat sending unit like the one in this post. There is no literal switch. It should be automatic when hot enough to need cooling.
 
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doublespaces

Administrator
Oct 18, 2016
7,764
AZ
1. Vent up because hot air rises. I figure this vents up makes the hot air escape easier than down.
2. Vents cut to allow for rear of fan to take up interior space.
3. Foglights do not fit with all hoses in the way in the front area.
4. Had to move SPAL fan and cooler more forward last might so the rear of the fan would stop hitting the front tire.
Hot air does rise, but with a massive fan like that, its not going to really matter. Also, the tire spin forward and down, you'll be throwing tons of rocks, mud and debris right into your fan/fins.
 
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matreyia

Captain
Apr 19, 2017
1,312
Hot air does rise, but with a massive fan like that, its not going to really matter. Also, the tire spin forward and down, you'll be throwing tons of rocks, mud and debris right into your fan/fins.

That's what I thought... then I did a test with mud road and dirt road... zero. Only on the back inner fender.
 

matreyia

Captain
Apr 19, 2017
1,312
That's crazy, and that wiring is no good man, get some proper connectors and marine heat shrink on that quick. You could could have just used a relay, bypass switch, and any decent fan controller.
Read the entire post. I said this already. There is no switch. The fan comes with a thermostat sending unit that is connected to a relay that automatically switches the fan on when it gets hot enough.
Those wires in the photo are connected with butt connectors. I will most likely add heat shrink in the near future to make things unexposed to humidity.
 

9krpmrx8

Sergeant
Nov 5, 2016
374
San Antonio, Texas
I know there is no switch but it's handy to have one to be able to switch it on full tilt in the event you need too cool down quick. I am not sure on the 335i but most cars us a logic that turns the fan off at a certain vehicle speed regardless of temp.
 

Jeffman

Captain
Jan 7, 2017
1,321
VT,
Just checking in to see how this ATF cooler / fan set-up has been working out for you.
Thanks.
 

matreyia

Captain
Apr 19, 2017
1,312

matreyia

Captain
Apr 19, 2017
1,312
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Reactions: doublespaces

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