Wrenching Mistakes Are Guaranteed. What You Do with Them Is Not
This story first appeared in the November/December 2024 issue of Hagerty Drivers Club magazine. Join the club to receive our award-winning magazine and enjoy insider access to automotive events, discounts, roadside assistance, and more.
I’ve owned something like 100 cars and have been wrenching for nearly 50 years. I like to think I have a good bead on the diagnose-repair process. I do, however, occasionally mess up. Below are three instances where I flat-out got it wrong, and what I learned.
The Bad Battery
One of my cars had developed a hard-starting problem characterized by slow cranking. The car typically sits in remote storage with the battery disconnected for months at a time. I recharged the battery, which was going on seven years old, but the problem remained. My handheld digital battery tester reported no issues, but given that the tool was itself 10 years old, I assumed it, too, had died. I could have tried the battery in another one of my cars but decided my aching back didn’t need that. So I bought a new battery. No reason to overthink it, right? Wrong. I dropped it in, and exactly the same thing happened. The problem turned out to be the starter motor.
Lessons: Overrule test equipment at your peril. And just because you don’t want to do work doesn’t mean it isn’t worth doing.
The Red Herring Starter
I was road-tripping with some folks when the points in the distributor of one fellow’s BMW 2002 closed up. This is very common, but what was unusual was that when I’d reset the gap, the problem would recur half a day later. And oddly, wherever we stopped, there seemed to be a foul smell—somewhere between propane and sewage. On the last day of the trip, his starter solenoid clicked but the engine wouldn’t crank at all. I checked the resting battery voltage, and it certainly wasn’t discharged; if anything, at 13.1 volts instead of the usual 12.6, it was a little high. I ran a wire directly from the battery to the solenoid. No difference. Given my recent experience misdiagnosing a bad starter as a bad battery, we procured a replacement starter. I installed it in a parking lot—and was stunned that it made no difference. Puzzled, I jumped his car with my own, and it cranked and started with no trouble. Conclusion? There was never anything wrong with the starter. He had a bad voltage regulator that had killed his battery by overcharging it and was pitting his points, causing them to close up. Had I followed my nose, I’d have figured it out sooner—a rotten-eggs smell is a textbook sign of an overcharged battery. A basic charging system test would also have clued me in.
Lessons: Don’t let your last blown diagnosis unduly influence your current one.
The Dizzy Distributor
I’d sent the distributor from my BMW 2002 off to be rebuilt. When it came back, I outfitted it with the proper new Bosch points, condenser, cap, and rotor. On the car’s test drive, it began running so horribly that I barely made it home. A professional wrench friend came over in his own 2002 to help. He yanked the distributor from his car and said, “I just drove over here, so this one’s known-good. Let’s drop it in your car.” I protested. Everything in my dizzy was new. It was the “known-good” one, not his. He mock-barked at me, “ARE YOU HAVING A PROBLEM OR AREN’T YOU?” He installed his tired-looking distributor in my car, and to my astonishment, my car ran like a sewing machine. “Now,” he said, “We’ll transfer over one component at a time to find the bad one.” Turns out, the brand-new Bosch condenser in a BMW box with a BMW part number was to blame.
Lessons: There is no “known-good”—there are only symptoms. Whenever you say, “It’s not that,” a red flag should go up, because you just admitted you have a blind spot around “that.” Also: Listen to professionals.
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Rob’s latest book, The Best Of The Hack Mechanic™: 35 years of hacks, kluges, and assorted automotive mayhem, is available on Amazon here. His other seven books are available here on Amazon, or you can order personally inscribed copies from Rob’s website, www.robsiegel.com.
Rob, your last point, “listen to the professionals” now did you not begin this essay by credentializing yourself by pointing out that you have your 50 service pin as a credentialed professional hack mechanic? And is it not true on more than one occasion you have ask your readers: “why do you believe anything I say?” So therefore what are we, your loyal followers, suppose to do: accept everything you say as carved in stone and from on high, or take everything you say with a grain of rock salt? We are confused????🫤🫤🫤
Oh and Rob, Best wishes for a safe and prosperous New Year….
NEW = Never Even Worked, or Never Ever Worked if you prefer. I once got burned by a bad condenser but it wouldn’t make spark at all. Now in that case it was a cheap “tune up kit” from the parts store, the kind in a blister pack to hang on a peg, but it was for a Bosch distributor. I chased my tail around thinking I somehow didn’t have the point gap correct so after double, triple and quadruple checking it I put the original condenser back in. Low and behold it started on the first try and with the cheap dwell meter now able to give a reading found the points setting was dead on at 50 degrees. So yeah don’t be fooled by parts that are NEW in the package either when installed or when they stop working shortly after installation. IE “it couldn’t be a bad ignition control module it was replaced just last month.
I like that you got through. The drama along the way made it an interesting story.
Number one rule to mechanic club is there are no absolutes.
Number two rule see number one.
Always keep an open mind especially with electronics.
No matter if you worked on car 5 years or 50 with ASE ratings there is always things to learn and consider.
The bad news is part is not very uncommon anymore.
sort of on a tangent with one of your comments, i work on staying humble. when i get in trouble is when i act as if i ‘know it all’, or make assumptions.
i found that, a lot more times than not, checking the basic items first got the issue figured out, and fixed (can you say “eh, i’ll clean the green mushrooms off the battery posts AFTER i replace the starter”). i think that’s what rob is saying here, directly or indirectly.
why is it that i first think the problem HAS to be caused by something complicated???
When it comes to starting problems, if that battery is more than 3 years old, step 1 is always replace the battery. You might end up replacing the starter too, but replacing a 3+ year old battery is never a bad first step.
The best practice is to first make sure the battery is fully charged then check current draw and voltage during cranking before condemning the battery.
I learned from a seasoned journeyman 50+ years ago when starting my trade as a mechanic when points and condensers controlled the spark that you are more likely to have more trouble after installing a new untried condenser than leaving the old proven condenser in place.
+1 = been there, got the t-shirt!
“Test, don’t guess”. And please don’t fall for the “Parts ’till it starts” method of diagnosis. Two classic phrases I still follow.
As far as the first story, rule number one for IFR rated pilots is “always trust your instruments” .
I only work on basic cars, no computers. Racecars and a pre-1980 Corvette. Occasionally repairs have led to more problems than they fixed.
When I call my genius mechanic friend, his first question is always: “What is the last thing you did?” It’s almost always the right question.
I also had to replace a bad alternator with a a newly purchased, re-manufactured alternator from a big name auto parts store 3 times before I got one that worked. Luckily I had diagnosed before I repaired.
As stated above, it is never a bad idea to replace a battery that is over 3 years old. I have owned several cars over the years that have needed a battery replacement at 3 1/2 years old. I prefer to not get stranded, so I consider a battery to be a basic maintenance item. In the past, I believed in battery chargers, but I got over it.
I steadfastly disagree with replacing parts (like batteries) solely because of age. Anything on older vehicles (yup, even condensers) can be tested with low cost tools. Stop guessing and only replace failed or failing parts. And I’ll see you all next year!
I’ve been messing with cars since 1963, and 14 of those years was with a Renault 4CV as a daily driver. Had to learn fast! But I’m still learning.
2024 lesson. A catalytic converter can disintegrate internally and plug the exhaust sufficiently to stall the engine.
2023 lesson: a dying condenser can cause all sorts of wonky running problems, ultimately resulting in a dead engine. First time it happened to me in 60 years of points and condenser ignition.
Wonder what new mechanical lesson I’ll learn in 2025?
Technitions make bobos all the time I did when I was working in the trade.
Replacing a seven year old battery wasn’t a bad idea. Why wait until your battery fails far from home?
I had a related misdiagnosis on a BMW motorcycle, it was parked with a battery tender, and showed 13 volts across the battery with a multimeter but not even a click from the starter. So I assumed the battery was good, swapped out a relay and even tore into the wiring in the headlight shell to test the diode in the fuse board. Still no start, so on a hunch I dug out the battery tester and hit the “Load” button ad watched battery voltage fall off a cliff. The fix was a new battery.
Another issue is documentation, on another motorcycle that had sat idle for many years I rebuilt the carburetor using the Chilton manual’s diagram and it wouldn’t run. Years later, with a good parts diagram I realized I had swapped two carburetor jets that were the same external size but very different internally, the bike started and ran first try