I finally put the fan mod on the top of my to-do list. Thanks to all who have done this in the past, and posted how they did it. Mine is the electrical box version with a couple twists. I purchased the motor and fans from Grainger. I picked up 2, 2.5 and 3 inch fan blades. Figured I’d experiment with them. The 3” became my motor cooling fan, and the 2” is inside. I initially put the 2.5” inside, but during my empty test run, I realized it moves too much air.
Here is the finished install. (sorry for some of the blurry pics)
Here is the assembly ready for the OBS.
Motor mounting in box.
Here’s a close-up of bolting the motor to the back of the box.
Big picture, I removed the factory bolts, and purchased two 8x32 by 2” fully threaded screws. Some details: Spin a nut and washer deep onto the screws, run screws into motor and screw them into the motor housing. Tighten nuts. Then cut off the head of the bolts with a cutoff wheel. The remaining bolt should be long enough to mount the motor to the box. Before I did that, I put 2 washers on each bolt stub. (can sorta see them in the photo—sorry for the blur) This holds the back of the motor just a hair off the box. I noticed without those washers, the motor shaft did not spin as easy after being tightened down. I’m guessing the motor got flexed a bit without the washers, making the shaft slightly harder to turn. It didn’t lock up the motor, but there was noticeable friction there without the added washers.
I used screws and nuts in the threaded box holes to hold the box the correct distance from the smoker as I marked/drilled/screwed in the aluminum mounting rails. They are 8x32 by 1/2" screws, held tight by nuts.
Drill the hole thru the back of the BS from the inside out. First remove the back to make sure you won’t hit the electrical wires going to the overtemp sensor. Put a piece of tape on the back of the BS so you know where they are for the rest of the project.
Run the fan onto a 3/16” drill bit (bit not in drill), hold it up against the back of the smoker where you want the fan (have V tray and bottom shelf installed), and spin the bit by hand to mark where to drill the hole. Remove the upper rack, install bit in drill, and drill hole as square/straight as you can. V-pan will catch your drill shavings to keep them out of the burner element. Drill a 3/16” hole. Once you have finished installing the motor assembly, you can drill the hole bigger for a little shaft clearance. Mounting the motor with a tight fitting hole will ensure you have it centered (I thought of this after I had an enlarged hole, and getting mine centered in it). My final hole size is 1/32” larger than 3/16.
Here’s an inside pic with a shield around the fan
It took me the better part of 2 afternoons, but I work slow and methodical.
Hope this helps the next person with their install. I appreciate all the great info on this site.
Drano
