Jamie takes the plunge and decides to replace the supercharger on his Mini himself...
Ben Franklin said that the only inevitabilities in life are death and taxes. I’ve got another one for he of the bifocals and stupid kite tricks; the supercharger on your Mk1 Mini Cooper S will crap out at around 80,000 miles. Time to go to work.
When you’re working on a car and things are going well it can be an almost cathartic experience. However, when things start to go wrong it can turn into the most frustrating experience a human can endure. Everything can be going swimmingly, parts are coming off the car just like the service manual told you they would and then you get to that one 8mm bolt that no ratchet extension in the Milky Way can get to. Soon you’re smashing, cutting and pinching your extremities, sometimes all at once. Then you throw a temper tantrum, toss away your ratchet and storm inside to watch television.
Memories like this make getting started on a project like replacing a supercharger quite daunting. I myself found procrastinating for days, then weeks then months. I was perfectly happy borrowing my friend’s spare SUV to go to and from work.
Finally I decided that I had to get it done. Partly because it had to be done, but more importantly to exorcize the demons from when I had to replace my head gasket [shudders].
After doing some research I found a place in Florida that specialized in rebuilding Eaton superchargers. I asked them over the phone if they did a lot of Mini superchargers. “Oh yeah” was his reply, “It’s like a third of what we do.” The interesting thing about these particular superchargers is that when they go bad, they actually still function as superchargers. They still compress air in to the intake manifold and everything. When the engineers were figuring out how to stuff everything in to the engine bay of the Mk1 Mini Cooper, they realized there was not enough room to have the accessory belt turn the water pump. Instead, they gave this job to the supercharger. The accessory belt turns the supercharger, and the supercharger turns the water pump, which is mounted, on the other side of the supercharger. This is where things go wrong. The gears tasked with turning the water pump start to strip and pretty soon the engine looses its ability to cool itself. Got it? Me neither…
After a few more phone calls to Florida, including one in which I talked them into installing a JCW pulley for no extra charge, a heavy cardboard box arrived at my door. It was Tuesday and I had planned on waiting for the weekend to do it. But I got excited, and took the next day off work.
I got up the morning and immediately got to it. Turns out, I needn’t have feared. Many of the same things that had to come off the engine during the head gasket replacement had to come off for this as well, and I realized I already knew how to take the things apart that had caused so much grief before. Even the bumper removal was pretty straightforward. That’s right, you have to remove the bumper to get to the supercharger.
The only thing that was irksome was that I had to pay $100 at the BMW dealer to buy a long piece of L-shaped steel to loosen the belt tensioner. I rationalized this by my telling myself that it probably wouldn’t be the last time I used it, even though the only thing it’s good for in the entire world is loosening the tensioner on a Mk1 Cooper S. Well, that and bludgeoning the German who decided to price it at $100.
Surprisingly, about eight hours after starting, the whole thing was put back together. I decided to take it for a test drive. I immediately noticed the improved torque between 2000 and 4000 rpm due to the smaller pulley. I continued driving, not straying too far from home in case any improperly torqued pieces fell off. Then it started to overheat and the expletives flew. My mind was racing as I pulled off to the side of the road, “What could I have possibly forgotten? I know I checked the old supercharger to make sure it was broken. Did I miss a hose? A clamp? A gasket?” Then a Zen-like sense of calm washed over me, and I began to see straight again. I forgot to refill the coolant.
I’m now proud to say the Mini is back to fighting strength, supercharging and cooling as it should. I can’t wait for something else to go wrong.
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