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Comment by sokoloff | Hacker News Reader

> My mechanic won't do it because he won't confirm that's the cause.

My experience is that a lot of independent mechanics will do what you ask them to do, so long as they think it’s not unsafe and have confidence that you’ll pay the bill without complaint when the task is done whether or not the problem is fixed.

Probably not a good “this is my first time meeting you, but please replace my flux capacitor” but if you’ve got a history with the shop, I’m surprised you couldn’t talk him into it. (I worked in a shop briefly in college. We’d do what the customer wanted, including installing parts they bought, but the only warranty was on a “we spent an hour; you paid for an hour; thus ends the transaction” basis.)

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Yes. I had a problem with a leaking transmission once and the shop refused to accept my diagnosis because "in all my years servicing transmissions, I never heard of that failing."

Finally, the service manager agreed to check it out with the understanding that if I was wrong, I still had to pay for the time they spent investigating.

I was right :-)

Debugging spider sense is definitely an upside of spending years working with terrible code.

I once moved into a place that was great, except the shower would start out hot, quickly drop to warm, and then stay warm for as long as we cared to try it. I hated this, so every time I showered I'd spend some time trying to debug it, despite knowing nothing about plumbing.

Eventually I asked myself: why do normal hot water heaters work the other way, where they stay hot a long time and then get pretty cold? Clearly, there's some way of keeping the incoming cold water separate from the already-heated hot water, like by putting the output pipe at the top and the input pipe at the bottom. But if you reverse them, you might get what we had.

I leapt out of the shower and felt the hot water heater pipes and sure enough, reversed. My landlord came over shortly thereafter and fixed it, and I felt very smug when I had my first properly hot shower.

I once spent over a year debugging a furnace. It would run fine, except every now and then on it would just refuse to turn on for a day or two. Eventually noticed it was only rainy days, and was due to it thinking the exhaust was blocked because there wasn't enough pressure differential between input air and exhaust.

Turned out the installer had failed to put in the high altitude kit which told it to expect a smaller pressure differential. Mostly it was fine, but on rainy days with low barometric pressure, the difference would drop below threshold. But I had to be home for enough rainy days to figure it out.

Ooh, well spotted. Correlation is correlated with causation!

> Correlation is correlated with causation!

That's a great quote. I think I'll use that instead of "where there's smoke ..." from now on.

This was me with a Suzuki vstrom with a bad solenoid. Mechanic ran 12 volts through it on the bench and refused to accept it wasnt working in the bike.

Bought my own solenoid online and surprise the bike started working again.

They were unit testing when they needed to be integration testing.

I've done that twice with some shops I didn't have any history with.

Once I got them to replace my gearbox oil even though they said it wasn't needed. With another one I brought them a third-party pedal and asked them to install it. In both cases it did solve my issue by the way, even though I might have been wrong.

They don't care as long as you're ok to pay for the hours regardless of whether it solves your problem or not.

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