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Auto Woes

In another consequence of the hurricane, we had a thousand-dollar repair bill on the BMW. Though actually, in a sense, the hurricane may have simply made us aware of a problem that had been ongoing.

As you may recall, I was blogging with power out by running my modem and laptop off a voltage inverter hooked up to the car's battery. On the Saturday morning before we got full power back (even with partial power, I couldn't get the DSL modem to work from the house current), I was letting it idle in the driveway to recharge the battery, while I watched the (infuriating) Michigan-Notre Dame game.

Suddenly, I heard a loud hissing sound in the driveway. I ran outside and the car resembled a steam locomotive, with its hood obscured by all of the dangerous DHMO in gas phase. I looked at the dash, and the temperature gauge was pegged. I shut the engine off, and let it sit.

The next day, I tried topping it off, and the water was pouring out as fast as it was going in, through a crack in the filler tank that had apparently ruptured.

I tried driving it, and while it ran smoothly, it had no power (top speed about ten MPH), which really started to concern me, because I was afraid that I'd warped or cracked the heads on the V-6 (though that didn't make sense, given how smoothly it was running).

I also couldn't figure out how I'd managed to drive it across the country two weeks previously, through the Southwest in the hottest part of summer, with no problems at all, but then have it overheat idling in the driveway.

Then, of course, the little cartoon lightbulb went on over my head. It has an electric fan to pull air through the radiator when the car isn't moving. Most likely scenario--the fan had failed sometime in the past, and I hadn't noticed it because I'd rarely let the car idle motionless for that long previously.

Sure enough, when we took the car to the repair shop, that was exactly what happened--a resistor had gone bad and the fan had quit fanning. Of course, the resistor isn't replaceable--you have to buy the whole fan unit from Wolfsburg, at over three hundred dollars. Also, it was a cascading failure--the incident, in addition to rupturing the plastic fill container, wiped out the water pump by running the bearing dry, and the thermostat. All told, about a thousand bucks, including labor.

The mechanic told us that he hadn't seen this happen before, but it didn't surprise him, because BMW had gone to a single, non-redundant fan about that time. I'm not sure why they don't just drive it off a belt like in days of yore, but I guess most modern car manufacturers prefer to only run it when it's needed, perhaps to not be a useless power drag, since it's rarely needed. I know that I have one on my eighteen-year-old Accord that's never had a problem. And of course, this would have been avoided if I'd been sitting in the car while it was idling, because I probably would have noticed the temperature creeping up (which would have been a much less costly way of discovering the problem than the catastrophic failure that it actually endured). But there's no telling how long it hasn't been working, or how long it would have been before I discovered it, if it hadn't been for Frances.

The good news is that the engine is all right. The power problem wasn't caused by a lack of compression, but by a slight warping of the throttle body so that the valve couldn't open properly. After cleaning it, they got it working again.

Posted by Rand Simberg at September 21, 2004 09:57 AM
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Sounds similar to the fan problems that are plaguing the early-middle nineties Ford Mustang GT's. There is a fuse that is supposed to go inline to the fan relay and somehow they forgot or neglected to include this in the wiring harness from the factory. Ford issued a recall to have the fuse added. Apparently it can overheat from constant cycling on and off. The fuse is merely a stop gap that prevents the extra heat and resistance in the line from shorting out the relay. My fan went out right about the time that I had upgrade my power control module with a power adder chip that, among many things, causes the fan to run more often in attempts to keep the engine cooler. No doubt sitting in the driveway idling for a long period will cause the fan to cycle constantly on and off.

I'm guessing that your engine doesn't have aluminum cylinder heads? My girlfriend's Honda Civic had a drain cock on the radiator fail and let the water out as she was driving. When she came to a stop the car died. Thats all it took to warp the head and require a rebuild.

I have a aunt that lives in Florida and she learned a long time ago that several 5 gal. fuel containers (usually can find them at a specialty racing parts store) and a generator are your best friends in Florida. The fuel containers are for the cars since going to the gas station after a hurricane can be a Mad Max Beyond Thunderdome experience. Her generator runs off of propane or natural gas (can be switched back and forth) for added efficiency. So she was able to run the fridge and a big screen tv and the lights around the house while the power was out for several days.

Posted by Josh "Hefty" Reiter at September 21, 2004 10:20 AM

In all honesty, the heads probably didn't warp because you caught it in time. If you had come out to a siezed engine, well, you know which creek you'd be up...

I think that there are a few reasons that the fans are electric instead of belt-driven nowadays. First, we have much better cooling technology, so there's no need to run a fan constantly as long as you're going over, say, 20 MPH (that's when the temp starts to drop on my BMW bike, at least). Second, with FWD cars, the engines are mounted parallel to the firewall, so all of the belts are on the side of the engine, rather than the front. Makes it tougher to get a belt to run on the front of the car.

This is all speculation, of course, as I haven't read up on the history of fans in engines at all...

The best time to buy a generator would likely have been March or April of 2000. All of the "Y2K panic" stock of generators would have been available for extremely deep discounts, as winter would also be over. I haven't priced generators recently, though.

Posted by John Breen III at September 21, 2004 10:46 AM

While that may be true in general, John, a BMW 323i is neither FWD or a sidewinder. All of the belts are on the front.

Posted by Rand Simberg at September 21, 2004 10:49 AM

$1000 to the BMW shop? A little high, but not surprising. I count myself lucky with any repair that's under $200. I also lament my misspent youth, studying physics and computer science instead of German auto repair.

Posted by slimedog at September 21, 2004 11:43 AM

I actually did misspend some of my youth repairing German autos (mostly VWs and Porches), and I've done a lot of work on previous 2002s that I've owned, but the new cars are really tough to work on without special tools, and they pack things in so tightly that it's really a pain. I've got a factory shop manual, and I still do things like brakes, but I didn't really want to have to take the cooling system apart. And only about three hundred of it was labor (at $80/shop hour). The biggest ripoff was the fan, which should have been repairable, but BMW doesn't sell individual parts for it.

Posted by Rand Simberg at September 21, 2004 12:04 PM

I understand that the BMW sedans are all RWD (with a few AWD exceptions), and thus longitudinally mounted. The part I left out, which I realised after posting, was that once manufacturers developed electric fans, they likely decided that it wasn't worth the hassle to have different types of fans for different cars, and went all-electric. Presumably energy consumption benefits were also weighed into that decision.

I'll also agree that modern engine compartments are WAY too crowded. To take the alternator off of the V8 in my Taurus, you need to remove the RF wheel, liner, and often times drop the subframe. My '97 Audi A6q had enough room to see the ground when looking in from above, and was MUCH easier to work on, but still more crowded than my roommate's 1972 Olds Delta 88.

Posted by John Breen III at September 21, 2004 12:15 PM

Auto manufacturers are gradually changing to more and more electrical accessories. First it was fuel pumps, then cooling fans. Now electric power steering is trickling down through the price range (first the Corvettes, then the luxo barges, then....)Electric motor driven AC compressors are starting to appear. The trend is toward hybrid drivetrains for higher efficiency and software load management with things like engine shutdown at stop lights. You're going to see more in the future.

As for emergency power, please consider a PV array with a deep cycle battery (you already have the inverter). Initial purchase price is higher than a generator at $5/Watt for the PV, but you can use it every day to slightly lower your utility bills and make an infinitesimal dent in the use of fossil fuels. We have an 82 Watt array here at XCOR and it's powered every rocket engine test we've done.

Posted by Dan DeLong at September 21, 2004 02:51 PM

I had the same nasty experience on my Alfa Romeo ('99 2.5 V6). 500 GBP, so rather more expensive than your bill - but as has been pointed out, it could have been a lot worse.

Re: seeing the ground through the engine bay: I could see tarmac through the engine bay of my previous car ('91 Saab 9000 2.3 Turbo), but the Alfa's engine bay is packed very tightly with Noisy Expensive Things that I know better than to mess with on my own. I do computers, and I pay other people to do cars, and I count it as a good investment - though if I ever move to somewhere where I have a garage and a non-essential car to practice on, I would love to learn...

Posted by Dominic at September 22, 2004 02:01 AM

Just to give some background on my Car experiences I've built up a few Chrysler big blocks. A 440ci for a friend of mines Dodge Challenger (with a 250 HP nitrous system) and a 383ci big block for my 66 Plymouth Belvedere.

Lots of guys that build up old 60's muscle cars install electric fans and electric driven water pumps to free up an average of 10-20 HP. Not much but every little bit helps. Starting in the 70's, into the 80's, and even on some American made trucks made today you will commonly see fans that have a temperature controlled clutch. When it is cold the fan will spin freely but when the rheostat on the front of the clutch picks up enough heat from the radiator it will engage the clutch causing the fan to spin and force air through the radiator.

Also in this day and age of high emmission standards the average operating temperature of the engine can greatly affect driveability and emissions output. Generally an average temperate of around 215 degrees is ideal for uniform cylinder combustion. In my Mustang I installed a low temperature themostat that runs at 180 degrees but my emissions output went through the roof. To pass emissions I had to run RxP additive to mask the higher concentrations of nasty stuff.

Posted by Josh "Hefty" Reiter at September 22, 2004 07:14 AM

I should have added that the fan clutch system I was talking about are belt driven systems not electric. Auto manufacturers have gone all electric on the cooling system to obtain more precise control of the engines average temperature and increase emissions performance.

Posted by Josh "Hefty" Reiter at September 22, 2004 07:38 AM

Fuel and water pumps and fans; fans were the first to go electric -- originally boosters, nowadays a combination of

  • less horsepower draw because it doesn't run when it isn't needed,
  • space and weight (electric fans can run faster and use more efficient airfoils, so can be smaller),
  • finer control of engine temperature, and
  • packaging -- sidewinder engines are tough to do belt-driven fans on, as noted, but even Hotchkiss-drive cars can use the space freed up by eliminating the fan and the space it needs to run (and vibrate) in.

I had a couple of mid-eighties Chrysler minicars (for which read: cheap) that had electric fans.

Next up: 18-cell batteries and 42V electrical systems -- which is what they're calling it, not "36 volts" as it would be using the same calculations that make cars "12 volts" and trucks "24 volts." After that, engine-driven and hydraulic accessories will gradually disappear, and air conditioner compressors will start migrating all over the car(s). The only thing left running mechanically off the engine will be a hefty alternator and the valves.

Even valves are a possibility. No way to get a strong enough solenoid at 12V (=13.8) to move fast enough, but at three times that, well, maybe. An engine with electric valves wouldn't need a starter motor!

Ric Locke

Posted by Ric Locke at September 22, 2004 07:53 PM

Redundant fans don't help all that much. My old Nissan had two electric fans, and unless you make a lot of effort to look it's impossible to tell when you've blown a fan motor. What happens then is the second fan has to work twice as hard, and blows shortly after the first.

If you hardly ever spend time in traffic, it's hard to even tell when the second one fails. When you're sitting at a stoplight in the summer and the AC is blowing nothing but hot air, though, it's time to get it looked at.

You got off rather cheaply. If your cylinder head had been as poorly designed as the early Chevy 4-banger heads, even a hint of overheat would have cracked it.

Posted by Slartibartfast at September 23, 2004 09:44 AM

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