I’m flirting with the idea of selling the Bavaria, so I brought the old girl back from the Monson warehouse and began addressing a number of issues. One of them was that the blower fan wasn’t working and never has for the eleven years I’ve owned the car. Of course, that’s the way we do things, right? We tolerate certain deficiencies and quirks in our cars, and only address them when it’s time to sell the car and it’s better to fix things than to apologize for them in the description, and then we enjoy the functionality and wonder why it took us this long to do it.
Fortunately, like its gorgeous E9 sister, the Bavaria’s blower fan can simply be unbolted from under the hood, as opposed to the one on its annoying little 2002 brother which requires the entire damned heater box to be removed and opened. Six Phillips screws hold the metal cover to the cowl; removing it exposes the top of the box. Gently pry off the ring with the mesh over the top of the fan, reach in with needle-nosed pliers to remove the two electrical connections, and undo three small hex-head screws secure the fan to the housing. That’s pretty much it.
Way easier than on a 2002.
Before removing the fan, you can and should test it in place by lifting up the mesh mesh cover. You can verify that the fan blades rotate freely, that 12V is reaching them when the fan slider is moved, and / or stretch a pair of wires directly to the battery to see if it spins with a direct infusion of current. Mine passed the first and second tests and failed the third, so it definitely appeared to be dead.
Accessing the terminals with the mesh cover lifted off.
Okay, I thought; I’ll replace the fan. I haven’t spent a dime on this car in years. First I need to remove it. Even though it simply unbolts, drawing it out from the top was partially blocked by the windshield wiper armature. The trick was to start the wipers swinging, then disconnect the battery when the armature showed the most clearance between it and the top of the heater box. Out the fan came.
Congratulations, mom and dad. It’s a blower fan.
I looked up the part number on realoem (64111357890, just like the E9), googled it, and… holy crap! It’s available new, but numbers were the $400 range. I saw no used ones on eBay. Well, we’re not going to do that.
I’ve never revived a fullly-dead fan, but I’ve quieted squeaky ones down by spraying SiliKroil into the bearings. It was worth a try. With the fan out and the terminals easily accessible, I lubed the points of rotation and wired it right to the battery. Nothing. Not even the spark of contact when I touched the wires to the battery terminals. So it wasn’t even as if current was flowing into the fan but it was seized. No current was flowing at all. That sounded like a broken wire. I used my multimeter to verify that there was continuity from the terminals down to the brushes, so if a wire was broken, it didn’t appear to be in that path.
My Lotus Elan +2 donates its battery for a fan jump.
I looked carefully at the fan assembly. It had three parts—the electric fan motor itself, the light-colored squirrel cage, and the black piece that’s held to the fan motor with four big springy clips and allows the fan to bolt to the top of the heater box . With 2002s, the fan with the blades on it is expensive, but the motor itself is used on multiple cars and is only about a $70 part. The trick is to buy the motor and reuse the old fan blades. You hacksaw the shaft off your old dead motor, press the remnant sawed-off shaft out of the center of the fan blades, then press the blades onto the shaft of the new motor. Unfortunately, the shaft on the Bavaria’s fan was completely inaccessible to being, um, hack-sawed.
I did a little reading up on the fan brushes. People wrote about replacing them by getting an assortment of brushes and cutting down the closest ones to make them fit. I wondered if maybe the brushes simply weren’t making contact with the rotating armature. I sprayed the whole thing with contact cleaner and spun it around, but it made no difference.
Then I noticed that there’s a little snap-on clip above each brush. I carefully pried them off and found that beneath each one is a rectangular recess where the brush sits. In it is a spring like the one on a retractable pen that presses against the back of the brush, so if you do this, withdraw the clip with your hand cupped over it to stop the spring from flying across the room. I would’ve swore I took photos of the spring and the back of the brush, but I can’t find them.
What’s behind door number one?
I sprayed a little SiliKroil down the recess, then tapped the back of the brush gently with the end of a 1/4-inch extension. By spinning the fan, I could tell that, when I pressed against the back of the brush, it now made contact with the armature because it slowed the fan down. I did this on both brushes, put the springs and cover clips back on, tested the fan on the battery, and…
Whooosh baby. Now that’s a good hack.
While I was in the heater box’s neighborhood, I addressed the issue that, like in the E9, the Bavaria’s heater box doesn’t have a shut-off valve like a 2002. Instead, it’s plumbed as always-hot, with an internal flap either allowing or blocking the heated air into the cabin. Of course, on a 50-year-old car, the foam on the flap is utterly degraded, so even when the slider is in the off position, hot air pours into the cabin. There’s a debate on whether, if you want to turn off an always-hot heater core, it should be blocked or bypassed. The argument against blocking it is that it a shut-off valve stops the as-designed flow of coolant from the back of the head and through the core, which does act like a radiator and remove some heat from the coolant. The argument against bypassing it is that you’re taking coolant that hasn’t had the benefit of being cooled by the heater core and returning it right to the water pump to be recirculated through the block. I used to be on “team bypass” until I understood that the main path of coolant flow is rising up from the block through the head and out the front of the engine, and that other BMWs with the same M30 engine use a block-off valve. This whole issue as well as several solutions is thoroughly in a post I did years ago on e9coupe.com. In it, I described my solution on my E9, which is a servo-controlled electric bypass valve that has the desirable feature that, instead of being a binary solution of either on or off, allows the knob to be cracked open slightly to allow a small amount of heat into the cabin instead of the furnace that results when it’s open.
However, on the Bavaria, I elected to choose a simple inexpensive solution (I know you’re shocked). I had an inexpensive Four Seasons 74620 plastic coolant shut-off valve that fits a whole variety of 1990s and 2000s-era Honda products in the garage. I didn’t realize it didn’t include a rotating arm, so I repurposed one off an old leaking 2002 valve and installed it. It sits nice and tight and unobtrusive against the firewall.
Not bad.
So, with not one but two climate-control-related hacks I should’ve done ten years ago, the Bavaria now has a fully-functional climate control system, and isn’t dumping heat at my feet when the a/c is on. Gee, I should think about selling cars more often.
—Rob Siegel
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Rob’s newest book, The Best of The Hack Mechanic, is available here on Amazon, as are his seven other books. Signed copies can be ordered directly from Rob here.
Tags: bavaria fan hack