Flex-a-lite Fan Failure

Posted by Mr. Leslie Wong On August - 26 - 2008

Flex-a-lite 116 Trimline Electric Fan

Five years ago, when I had our BMW Bavaria‘s radiator re-cored, the radiator shop said a two row core would be enough. I’ve never had any cooling problems.

Instead of replacing the water pump mounted cooling fan, I bought a Flex-a-lite 116 Trimline Fan. It’s a 16″ fan that is 3.5″ deep. The airflow is 2215 CFM (62747.8 LPM) and it draws 11A.

Flex-a-lite says there should be “at very least 1″ from the closest part of the fan to the radiator“. Because I didn’t have that much room, I mounted the fan in front of the radiator, as a pusher.

Flex-a-lite armature

To switch it on, I mounted a thermostatic switch (61 31 1 364 872 82D) on a bung on the radiator lower hose connection. The other part of the switch was connected to a relay for power.

Because the climate is cool here, the fan rarely switches on. But yesterday when it switched on, I heard a grinding noise. I was hoping a leaf got stuck in it.

Flex-a-lite field magnet

I had to pull the radiator to remove the fan. It made a grinding noise when I turned it by hand. I disassembled the motor by removing a couple of Torx screws and a pin retaining the motor shaft to the case. Inside I found a DC motor, not unlike the ones I used in my slot cars, except this one had 4 magnets and 16 poles. I have used Koford quad magnets in my slot cars.

One of the permanent magnets had become unglued from the case. The armature’s poles had distorted slightly from turning against the loose magnet. I used JB Weld to glue the magnet back onto the can and a large screwdriver to straighten out the armature poles.

Flex-a-lite brushes

When I pulled the armature out of the casing, the four brushes and the springs shot out. While wondering how I was going to hold four spring loaded brushes in at once, I noticed two holes at the end of the brush holders. I put a piece of copper wire in each one so I could reseat the armature end bearing and connect the brushes.

After I reassembled and tested the fan, I ordered a new one. I figured $100 USD for a new fan is better insurance for preventing an engine meltdown, even though a 5 year life span for the old motor seems just OK. Maybe when I get the new fan, I’ll put some dielectric grease between the motor covers and the casing to seal it a little better from moisture.

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