Deep Car Thoughts With Rob Siegel, the Hack Mechanic

Staff Blog

Staff Blog | Jul 07, 2016

Rob Siegel knows his way around the underside of a car. It's experience that's hard-won after decades of messing around with old European cars, including, but not limited to, a lot of BMWs. For a quarter century, Rob's been writing the "Hack Mechanic" column in Roundel the BMW Car Club of America's popular monthly magazine. In 2013, he wrote Memoirs of a Hack Mechanic or How Fixing Broken BMWs Made Me Whole. This week, he published a new book -- The Hack Mechanic's Guide to European Electrical Systems -- with Cambridge (our fair city), MA-based Bentley Publishers.

We pestered Rob for a few minutes of his time and grilled him with questions that get to his philopsophy about cars, life and busted knuckles.

Car Talk: What was your worst experience with a car?

Rob: There were two, separated by 35 years.

As I write in my first book Memoirs of a Hack Mechanic, the 1973 Triumph GT6+ I bought my senior year in high school (1976) proved that everything bad you ever heard about British cars is true -- the electrical problems, the rust, the metal fatigue, everything. I am not exaggerating when I say that, while driving it at night, the headlights would sometimes spontaneously shut off. Or that while driving it in the rain, the wipers would spontaneously fail. Imagine what fun it was driving at night in the rain.

Everything you've heard about the GT6+: confirmed.

And the rust. Keep in mind that, at the time, this was only a three-year-old car. The attachment point of one of the rear trailing arms to the undercarriage of the car had already rotted clean through, causing the car to be highly unstable on spirited acceleration or cornering (this was welded up as soon as I bought it). In addition, the GT6+ had specific metal fatigue problems because it was basically a Triumph Spitfire with a hatchback added and the four-cylinder engine replaced with a six-cylinder from a TR6 (well, a slightly smaller six; 2 liters instead of 2.5), so every part of the drivetrain behind the engine would get ripped apart by the extra torque. I had a driveshaft crack. I had universal joints on the half axles literally rip out.

Again, I stress that this was a three-year-old car.

Some revisionist history has been written about the bad reputation of the Brits. I believe that Sports Car Market recently had a piece describing how well these cars behave now that they're pampered classics living in Scottsdale, and wondering if it was really all that bad. It was. Of course, in terms of desire, that changes nothing; I now own a dead '74 Lotus Europa Twin Cam Special, and I badly want a TVR 2500M.

Supermodel looks, Teutonic performance. What could go wrong?

The second nightmare car was my 1999 BMW E39 528iT 5-speed Sportwagon. E39 wagons are a pretty good-sized wagon, about the size of a Taurus, so they have lots of room. The 5-speeds are rare, and those with the sport package are practically unicorns, so they're a bit of a cult car. Mine was black on black. The sport package lowers the suspension about an inch, so it's got a nice hunkered-down look about it. E39s (and modern BMWs in general) can be high-maintenance cars, but my lord, this one seemed to be the poster child for things going wrong.

In addition to the usual cavalcade of bad final stage resistors (that can drain the battery during a workday), cooling system problems, and broken rear tailgate latches, the car suffered failure of the Crankcase Ventilation Valve (CVV), also called the oil separator. Most post-OBD-II cars have something like this, and it's actually a pretty common problem with BMWs in cold climates (meaning Boston and Chicago). As the oil heats up, the valve separates the water and lets it boil off, but if it's very cold out, like 20 degrees, and the car is run for a few minutes and then shut off, water can get into the valve, not have the chance to boil off, then freeze there. Depending on which position the valve freezes in, it'll either send oil into the valve cover, shattering it because it's plastic, or into the intake manifold, hydro-locking the engine and causing it to bend rods just like if you drove into water. In my case, it was the latter, but I shut it off just before the engine hydro-locked. I spent weeks dealing with the fallout.

Then, when I got it back together and took it on its maiden voyage, a front spring broke and the broken end punctured the tire. After dealing with that, the pneumatic rear self-leveling system began to go bad. It's kind of a cool system; you can throw 800 pounds of cinder blocks in the back and the compressor will inflate the air bags to level it out, but there are no rear springs. If the pneumatics leak catastrophically, the car is a beached whale, with the insides of the rear fenders sitting on the tires. Finally I sold it to a guy in California (yes, they're rare enough that he bought it and shipped it out), who, I'm sorry to say, continued to have problems with it. I now have another E39, a 2003 530i Sport, so, on one hand, you can say that, like with the Brit bits, I never learn, but this one has been fine.

Car Talk: What got you interested in BMW specifically?

Rob: One of the things I write about in my first book is the subject of "imprinting," how many of us have the same story of being in some car when we were 13, having it impress us, and imprint on us, as it were, causing us to follow it around for the rest of our lives like geese imprinting on a glider.

The 2002. Too much for Rob to resist.

In my case, when we were living in Amherst, Massachusetts, a Hampshire College student who lived with us had a 1971 BMW 2002, forever impressing me with what this boxy little German sedan could do. Then, about seven years later, this same gentleman called me up out of the blue. He'd started a software company in Cambridge and offered me a job, initially as a gopher. He had a 530i, then a 733i, both sticks. I got to drive them both over hell and creation. The feeling of synchronicity of these cars, how every molecule of the car felt like it was vibrating at the same frequency, was absolutely astonishing.  When I moved to Austin, Texas, in the early 1980s, I began buying BMWs, mostly 2002s that needed work, fixing them, holding onto the nicer ones until something better came along. It's what I still do.

Car Talk: How did you get started writing about your experiences?

Rob: I joined the BMW Car Club of America (BMW CCA) when we returned to Boston in 1984, and learned that, although the club was national, it was actually headquartered locally, with the club office just outside Harvard Square, and Roundel magazine assembled in Newton at the home of its then art director and subsequent editor, Yale Rachlin. I began by sending in unsolicited articles, which ran when there was room. In 1986, Yale called me out of the blue, saying that he'd become Roundel's editor, and asked me to write for him regularly. I began with a series of articles called "Confessions of a Hack Mechanic." This soon turned into "The Hack Mechanic" column.I've written monthly for 30 years.

"The first monthly column seemed easy. The second was a little tougher. When the third deadline hit, I panicked."

But I was used to writing repair articles, well-researched "use 10mm wrench to put bolt B in slot C" sort of stuff and sending them in when I was good and ready, not on a monthly deadline. So the new monthly schedule required some getting used to. The first monthly column seemed easy. The second was a little tougher. When the third deadline hit, I panicked. "Boss," I said to Yale, "I got nothing."

"You DO fix cars, don't you?" he asked.

"Um, yes."

"Did you fix anything this month?"

"Um, yes."

"Well, write about whatever it was you did."

This was the beginning of, as current Roundel editor Satch Carlson says, my writing about my getting myself into and out of BMW-related trouble. At first, I thought that this sort of storytelling was lazy, that I was short-changing my readers. This was all pre-Internet. I couldn't see that I was right in the middle of a fat bell curve. It took me years to understand that there were thousands of people just like me, working by themselves in their garages, at night and on weekends, trying to keep their cars running, trying to save money by doing so, and enjoying it. I eventually learned that the more I wrote about what stupid things I did, what went wrong, what lessons I learned (or didn't learn), the more it resonated with Roundel readers.

Car Talk: What do you hope readers get out of your new book?

Rob: Ah. To quote one of my own songs, I hope they have no fear. Or, to go left brain, I hope the book helps them to manage their fear.

The Hack Mechanic Guide to European Automotive Electrical Systems is a thorough romp through the important electrical aspects of cars. The European part is mostly market identification. The publisher, Bentley Publishers, is primarily a publisher of repair manuals for European cars, and most of the photos in the book are of my and other Bentley employees' cars, which are European. But obviously there aren't European electrons and Japanese electrons; the basics are all the same. So the book really applies to most cars, not just European ones.

After you get through the preface and safety chapters, the first word in the book is literally "click" -- the dreaded sound you hear when a discharged battery engages a starter, but the starter can't turn the engine over. I tell you to grab a multimeter (and, if you don't have one, to run down to Harbor Freight and buy a $5.99 multimeter) and check your battery voltage. I explain that, with the engine off, it should read 12.6 volts if the battery is fully charged, and with the engine running, it should read just over 14 volts if the alternator is charging the battery. I then congratulate the reader that they're over the hump, that they just used a multimeter to perform the most important two electrical measurements on a car. That really sets the tone of the book -- that automotive electrical systems can be demystified and explained, and that you can do quite a bit of troubleshooting yourself by following the book's step-by-step procedures.

I then explain how electricity works in a car, covering topics like the definition of voltage, resistance, current, and electrical circuits, but doing it in a way that is specific to cars, and clarifying things that confused me for many years. (For example, resistance itself does not generate heat. It is the flow of current that generates heat. Resistance, rather than being the boogieman many people think it is, is in fact the thing that prevents your car from being one flaming short circuit, rather than causing it.)

I go into multimeters (digital volt ohm meters -- DVOMs) in detail, explaining that, really, the $5.99 Harbor Freight special is fine to keep in your glove compartment to measure your battery voltage if the car won't start, but for actual troubleshooting , you're better off spending closer to $25 for an autoranging meter. The book then covers the common electrical measurements (voltage, resistance, continuity, and current) in a lot of detail, explaining exactly how to configure the meter for the measurement, whether the circuit needs to be powered or unpowered, etc.

The book then goes through the topics you'd expect an auto electrical book to cover (battery, starter, alternator, ignition, wiring repairs, fuses, how to diagnose a parasitic drain that runs down your battery, how to read wiring diagrams). It has very thorough sections on electrical relays and on general electrical troubleshooting.

The last part of the book gets into issues on newer cars. On older cars, the signals are static. That is, for the most part, 12 volts are either there or they're not. But on newer cars, many of the sensors -- oxygen sensors, crankshaft position sensors, etc -- output what I refer to as dynamic analog signals. These are signals that change while you're measuring them. They may change slowly, or quickly, or periodically (in a repetitive pattern). In particular, many sensors such as ABS sensors or crankshaft position sensors output a sine wave or a square wave, and as the wheel or the engine spins faster, the frequency of that signal increases.

A lot of people hear words like "sine wave" and "frequency" and they freak out, thinking they'll never understand it. And on-line information on these sensors is often pretty poor. Look on youtube at videos of how to test an ABS sensor. Many of them will say things like "test for resistance across the pins of the connector." They won't tell you that a) older ABS sensors are a Variable Reluctance Transducer (VRT) which has a pick-up coil, and what you're testing for is that the windings of the pickup coil aren't broken, b) newer ABS sensors are Hall Effect and have no pickup coil so this won't work, and c) even if the coil tests out as continuous, you still need to check that the sensor outputs a sine wave or square wave whose frequency increases as you spin the wheel faster. In this book, we give you the basis to understand all of these things.

Car Talk: You're a vintage car guy, but you don't seem like you're afraid to tear into more modern stuff, too. How do you think DIYers are going to satisfy that urge to mess around with their cars as vehicles get increasingly less DIY friendly?

Rob: On the one hand, there's this myth that, because modern cars are "computerized," you can't work on them. And it's just not true. Many of the normal wear and tear parts like brakes, shocks, exhausts, and cooling systems haven't really changed all that much. So, if you like working on cars, and your daily driver reaches the point where it needs a little love, you shouldn't think that you can't lay hands on it just because it's got an in-dash nav system.

On the other hand, sadly, it is true that cars have gotten way less DIY-friendly. For example, above, I essentially said that working on a cooling system hasn't really changed all that much. That's true, but there's a lot more stuff -- layers of plastic with wiring clipped onto it -- you have to take apart to get at something like a water pump or a thermostat.

I think people naturally find their own comfort zone with most of these things. They look at a repair manual, read some threads in enthusiast forums, look at a few videos, and have one of two gut-level reactions. The first is "that doesn't look that bad." The second is "are you freaking KIDDING ME? There's NO WAY I'm doing that."

Car Talk: Has anything ever caused you to walk away from a project?

I'm really pretty good about not biting off more than I can chew. For this reason, I don't "restore" cars. I don't buy something and immediately begin taking it apart with dreams of stripping it down to bare metal and making it look like new. Even when I had my 3.0CSi repainted in 1988, it was a "rolling restoration." It was incremental. The car was never off the road for an extended period during the process. There's no way the end product can compete with a full rotisserie job, but I don't really compete with anyone about anything.

The car that's stressing all of this is the '74 Lotus Europa Twin Cam Special. I always wanted one, and they're still pretty cheap. I bought it three years ago, sight-unseen, off Craigslist in Chicago, with twenty thousand original miles and a "ran when parked" seized engine, for six grand. A friend of mine has an Elan, so he knows what's what; he looked at it for me and negotiated the purchase.

In one feverish weekend I yanked the drivetrain out and tore the engine down. It was then that I learned how Colin Chapman's (Lotus' founder) purported design philosophy to "simplify, then add lightness" actually manifests itself in mechanical terms. As a weight savings measure, on many mid-engined race cars, the car has no rear subrame. Instead, the transaxle is a "stressed member," meaning that the lower control arms for the rear wheels attach not to a subframe but to the bottom of the transaxle. This is how the Europa is designed. But think about that for a moment, because it means that, when the drivetrain is out of the car, there's nothing affixing the camber of the rear wheels. They just flop around like that guy's broken ankle in the old ABC Wide World of Sports "agony of defeat" reel when he slides off the ski jump. So having bought this car in Chicago, had it rolled out of the garage where it sat since 1979, had it rolled into a car carrier, trucked to Newton, unloaded, rolled around the block, and rolled into my garage, once I removed the drivetrain, I'd magically turned this "roller" into a beached whale. You see lots of abandoned projects on Craigslist advertised as "roller, engine out." The Europa ain't rolling anywhere. It is not only dead in my garage, it's dead and immobile in my garage. I can't even easily sell it as a roller. This leaves me feeling very exposed on the project.

(Road & Track)

I disassembled the engine and got the piston unseized, and took the engine to a noted Lotus guy out in Ayer, Massachusetts, but he would not quote me a price. I spoke with another guy whose engine he rebuilt, and learned that he paid about twelve grand for the rebuild. I don't want to pay a quarter of that (though I'm sure I will), so I took the engine back and brought it into a more conventional machine shop nearby me in Waltham. That was about two and a half years ago. Never tell a machinist that you're "not in a rush." Bad idea. It's like telling a plumber that you're not in a rush. Hello, back burner. I did get the head back, and the block has been honed for the new pistons, but then work pretty much stalled on it. I'm hoping to get the pieces back this fall so I can assemble the motor over the winter. This will be the third winter I've said that.

So, my cost-containment strategy on the car is literally to do nothing until I get the engine back. Once I get it back, I will do the appropriate "while you're in there you'd be an idiot not to" things when I install it -- new engine mounts, new bushings for the trailing arms -- but I am not going to throw time and money into the car until I return it to the state it was in when it came into my garage, which is... complete and rolling. I then will make some tough decisions on whether to keep going or to bail out of the car.

Car Talk: What are you working on now?

Rob: Well, I'd like to say that I'm working on the Lotus, but for the reasons above, that's not really true.

I have a thing about having air conditioning in vintage cars. I find that it dramatically increases my usage of the cars, and thus my enjoyment of them. I've gone to ridiculous lengths to retrofit a/c into my 3.0CSi and to rejuvenate it in my 2002tii and my Bavaria. The single longest chapter in my first book is about a/c in vintage cars.

A few years ago I bought a Euro 1979 BMW 635CSi. The Euro cars don't have the giant "diving board" bumpers, and on the 635s in particular, the difference is dramatic. It almost looks like a different car than the big-bumpered US versions. This one is gorgeous -- Polaris (silver) with a black sport interior, front air dam and rear spoiler, no side marker lights, and black stripes on the sides and on the air dam. I almost didn't buy it because it no longer has the original M90 engine or the dogleg close-ratio transmission... and because it doesn't have air conditioning. But it's so damned cool I bought it anyway. It's just got gobs of presence.

I drove it a few months back to "Sharkfest," the event for vintage big BMW coupes (3.0CS, 635CSi and 850s). It was 2100 miles round trip to Chattanooga Tennessee. The event was in late April, so temperatures were still reasonable. That is, until I got about 150 miles north of Chattanooga. Then it got very hot, I began wilting in the car, and I pined for the cold a/c in some of my other vintage cars.

So I'm beginning to go through the process of accumulating the pieces of the air conditioning system to retrofit. As I write in the first book, the project breaks up nicely into a bunch of separate small jobs. You buy a new modern rotary-style compressor and a bracket and mount it to the engine. You buy the largest new parallel flow condenser that'll fit in the nose of the car and mount it. You buy the largest new high-quality fan that'll fit on the condenser and mount it.

But the biggest piece of the puzzle is the evaporator assembly (the unit that sits under the dash, on the transmission tunnel, that actually blows the cold air at you) and the console that surrounds it. In the hot rod world, because hot rods are do-it-yourself creations, there's a lot of use of generic evaporator assemblies, but in a vintage German car with a gloriously minimalist functional interior, you really need the original a/c pieces or it's going to stick out like a sore thumb. Fortunately the interior a/c pieces of a '79 Euro 635CSi are the same as a US-spec 633CSi. So I'm looking for a cheap 633CSi parts car, one where I can carefully photograph all the a/c wiring and brackets and whatnot before pulling it out.

Car Talk: Do you have any advice for our readers?

Two things, both hard-won bits of wisdom.

First, I've learned it's a really good idea, and hugely stress-reducing, to separate one's daily drivers from one's enthusiast cars. Sure, daily drivers do sometimes need to be repaired, but in general, since you don't need your enthusiast car to be running at 9am on Monday morning, it's just way more relaxing to do 20 minutes in the garage, install your three bolts a night, and be able to close the garage door and walk away from a repair for the evening.

Second, go easy on the quest for perfection. People watch too many car shows and believe too much of what they read in the comments on Bring a Trailer, that they should spend the most money and buy the car in the best possible condition they can. That's true -- if they have the money. People with means can always buy things that people of more modest means can not. The rest of us have to function within something resembling a budget. That's not news. And yet, people act as if these rules of reality vanish when you're talking about vintage cars, that there's one way to do it: the right way and all that crap.

How about this? How about buy the car you can afford, and enjoy it? Because you know what? When you've cratered your family finances and damaged your relationships with your loved ones, all in pursuit of getting that car incrementally closer to perfection, you know what? Spoiler alert: You're not actually going to be any happier.

Rob Siegel's new book, The Hack Mechanic Guide to European Electrical Systems is avaialble at You can read a full review of the book at

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