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A Mechanic's Life - Tales From Under the Hood

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  • hydrogen gas---remember the Hindenburg!

    Another good way to blow your face off is to apply a hi-amp fast charge to a completely discharged battery.
  • srs_49srs_49 Posts: 1,394
    edited November 2012
    I'm wondering if the long road back to the battery will steal a fair amount of current away from that dinky charger. Sure, a heavy jumper cable, no problem, but pushing 1 amp through a 12 foot long connector cable might result in the charge taking a very long time

    Couple of things to consider. That "long road back to battery" has to be able to supply whatever the cranking current that's needed for the starter motor, with acceptable voltage drop, right? Whats typical cranking current? 50 amps? 100 amps? 200 amps? So that 12 foot cable from the battery to the engine compartment has to be able to pass that amount current with only a volt or two (or three) of drop. So the resistance has to be pretty small, say less than 20 milliohms for a 2V drop at 100 amps (from V=I*R).

    Now, what is the charging current fromr your charger? Say it's 10 amps. Through that same cable, you would drop 0.2V (10 amps * 20 milliohms), probably not enough to affect the charging of the battery.

    Just for reference, 10 ft of 8 gauge cable only has a resistance of .006 ohms (6 milliohms), less than the 20 milliohms I used in the above example.
  • thecardoc3thecardoc3 Posts: 1,521
    edited November 2012
    Lets start with the statement about pushing one amp of current through the cables. Whether they are 12", 12', or 12 miles, your statement set the condition that one amp of current is flowing. As the resistance of the conductor increases, the voltage applied to the circuit would also have to increase to maintain that one amp of current. The question then becomes how much more potential would be required for the extreme length of the cable? We could figure that out if we wanted to.

    Now back to the reality of the BMW. At 1 amp of current, that conductor's resistance would only create a voltage drop measurable at the most in the thousandths of a volt (it may be in the millionths, but we will use thousandths to keep the math simple). Easily negligible. Raise the current to ten amps, and your voltage drop is now ten times larger. Go up to 100 amps, and your voltage drop is another ten times larger, and is only now into the tenths of a volt range.
  • marsha7marsha7 Posts: 3,661
    It has been years since I was at Dad's shop (it closed in 1986)...the big lathe we had (6 foot bed) was a South Bend...the drum/disc lathes, I have no idea of the brand, but they stood about 4 feet tall, much larger than the units in service stations...

    We had a milling machine for warped cylinder heads, and we had a valve grinding machine to grind out the grooves in valves, and, boy, did they look beautiful and polished when we were done...

    We used the big lathe to grind down grooves on flywheels, beautiful smooth surface when we were done with them...also cut the copper on armatures so new brushes had full contact when starting...

    Life was different back then...
  • thecardoc3thecardoc3 Posts: 1,521
    About 8:30 I expect to hear from someone who called me last night right before the training class I was presenting started. Her car broke down last friday in the parking lot where she works. Then over the weekend she lost her keys. Its a 2003 Taurus and by her description she has had a lot of problems with this car in the two years that she has owned it. First a freind borrowed it, wrecked it that took a few months to be repaired. Then it wouldn't start a few months back so they replaced the battery, then when it didn't start again it got an alternator, and then someone else replaced the starter and now it's broke down again.

    She wanted it towed to the dealer, but everyone she called has said that with where it is sitting, they can't get to it. She has been told it has to go to the dealer because while they can make replacement keys, they have to program the PATS system to make them work.

    But, the car wouldn't start before she lost her keys. So this is now a minimum of two unique operations. She has already had what sounds like a half of a dozen attempts at fixing a fundemental issue without success, and she has managed to add an entire layer on top of that. I have up until 10am to solve every facet of this vehicle issue and then I have to hit the road for where I am teaching tonight.

    Does this sound like fun to you? Someone has to completely solve this and get the car to be reliable so that she can simply use it for a few years. Sometimes it's really dissapointing how we would have found and dealt with the primary problem months ago and yet we never got the chance. We can handle her theft deterrent retrain right in the parking lot where the car is at. I will have to open up the locked car, and if necessary I have tools that I can use to lift the car and roll it out of where it is at so that I can put it onto my flat bed.

    BTW, reflect for a moment the $$$$$ investment that we have in place, just to be "service ready" and solve this problem for her in an efficient manor.
  • This sounds more like the lyrics to a country western song. I might have hung up. :P
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,267
    edited November 2012
    Hahahahhaha; touche.

    I'm really curious as to what the problem is with the Taurus. After I sold my Escort, which was quite reliable for me, the lady that bought it said the alternator failed and then later that it "wouldn't start." I had replaced two failed alternators in the time I owned it (exactly one year apart from one another) and had recently replaced a failed starter. Aside from those, though, I had no issues with the car starting and had no reason to suspect it might act up at any time in the near future.

    Well, she ended up moving out of state and sold the car. Oddly, I happened to spot the car (with new owner) at a gas station about "five minutes" after he purchased it. I gave him some extra keys and a repair manual that had been toting around in my car for two months waiting for the other lady to pick up, and we chatted for a little while about the car's history. I noticed that the car did, indeed, have a new alternator, along with a new battery, but didn't see anything else that looked different from two months prior.

    I'm curious what the problem on this Taurus ends up being, as it sounds like maybe that could be the root cause of the Escort's issues, too. I could chalk one failed replacement alternator up to a poor rebuild, but two within only 2.5 years? It might be something more....
  • thecardoc3thecardoc3 Posts: 1,521
    I'm curious what the problem on this Taurus ends up being, as it sounds like maybe that could be the root cause of the Escort's issues, too. I could chalk one failed replacement alternator up to a poor rebuild, but two within only 2.5 years? It might be something more

    You cannot associate the problems that one car has to generate the repair answer for another. Your Escort may only have been suffering from substandard repair components, or a lack of proper testing and maybe there was never anything wrong with any of the alternators.

    As far as the Taurus goes, she was a no-show. On our way out of town I drove past it and saw where it is sitting. I can get it out of there, but only after hours when there are no-other cars in that driveway that serves as the parking lot that goes all the way around the building. My flatbed probably cannot make the turns at the corners without needing some of the yard, it's that tight. Add the other cars parked there and it won't fit, period.

    I asked if anyone wanted to guess what kind of investment it takes to be ready to do the whole job for her. The truck represents over $70,000 all by itself. The scan tool, and software licenses, oscilloscope etc. easily push the total over $100K.

    I am the only tech/shop that could handle her situation completely, with no outside assistance. The pressure to be too cheap has left everyone else short of everything that would be required, and this is a ten year old car. Think about that for a bit.
  • I'm surprised all your alarm bells didn't go off prior to even considering working on this car.... :P
  • obyoneobyone Posts: 8,065
    Since you're talking about cost of the equipment to properly do a job let me ask you this. Do you ask for a down payment on any type of job or estimated cost of a job?

    For example say someone has '99 RX300 towed in to your shop and you estimate $13K to R/R a sludge motor. Guy tells you yeah go ahead and do it. Do you ask for a down payment? For what amount?
  • thecardoc3thecardoc3 Posts: 1,521
    On a repair of that magnatude, absolutely a deposit is required. They must pay the parts up front. There simply isn't a choice in ther matter because we don't have the kind of money that would allow me to buy an engine and sit on it for any length of time.

    The greatest fears with repairs like that is a customer who says do the work, and then never picks the car up. Worse yet since Pa doesn't have a mechanics lien law they could report the car as stolen, and when the police find it they take it away form us and return it to the customer without the repair being paid for. We are essentially left to sue for the repairs but the odds are we win the case but still never see a dime.

    I have had cars that the owner stopped making the payment on and get repo'ed that we had a repair waiting to be paid for. We have been ripped off for quite a sizeable amount of money that way through the years.
  • thecardoc3thecardoc3 Posts: 1,521
    I'm surprised all your alarm bells didn't go off prior to even considering working on this car

    Oh they were going off allright. The problem is we are so much about trying to help people that we often forge ahead no matter how rough the seas or dark the clouds are.
  • isellhondasisellhondas Issaquah WashingtonPosts: 17,346
    It's nice that you try so hard to help people but sometimes a shop just has to decline a job.

    " I appreciate the fact you called on us to do this job but I just don't feel comfortable doing this job when the cost of repairs will be more than the value of the car"
  • The buddhists have a term for that...it's called "unskilled generosity".
  • thecardoc3thecardoc3 Posts: 1,521
    Spent some time trying to look that up, found lots and lots of stuff but nothing that I felt explained the concept.

    Ran into a guy this evening, really didn't know who he was but it didn't take too long and I realized it wasn't comfortable having a conversation with him.

    Eventually the conversation turned towards what I do for a living, he was instantly interested because he has an oler Corvette that he claims he wants to sell but the radio doesn't work. He thinks (suspects) that there is wiring damage caused by a rodent. He wanted me to go to where he has the car stored to check it out.

    Sorry, that's not how it works. I'll do remote diagnostics/repairs for another shop and may choose to do that for a long time customer, but not for someone that I just met.

    Well it turns out we had a dealing with him about eight years ago, and now that he knows who I am things changed a bit. Another shop brought a cadillac to me because of a TPMS issue. I'm not a tire shop, but having the tools to deal with TPMS simply was in line with my overall approach. Back then I was the only shop equipped to fully handle that "new" technology. They couldn't get the light to go out and though there was a problem with the car. I was slammed with work but made room for it.

    The only thing I found was the tires were over inflated, otherwise the system was working just fine. Inflating the tires correctly extinguished the light and warning on the car. (Spec 30psi, the tires were at 36psi)

    I recall the guy coming and picking up the car and being all irate. Heck all we did was confirm that the system was actually working correctly when it alerted for over-inflation as well as under-inflation. That was the first time we had seen a car do that. Back then there was no published proceedures for changing the pressure specs that the system looked for. It was basically set by the factory and beyond our reach. Today, some manufactuers do have ways for the tire pressure system to be updated for changes in tire pressure specs, but not back then.

    This guy still holds that against us. Combine that with his story changing several times until he realized that I actually recall that incident and I was glad that he never became "a customer" and got to tell him so. At one point he claimed he had to wait at my shop for three hours, and I had no problem pointing out that the tire store brought his car to me, and an hour later he picked it up. Then he tried to claim that we charged him too much, except he didn't pay anything because we only looked at it as a favor to the tire store. Then he claimed that "he fixed it himself", yea sure he did. His Caddy isn't on the list of cars that I know of for which we can do an update for the TPMS spec. Even then we have to go online and register (request) the spec change with the manufacturer, and they release the adjusted software to us, and then we do the reprograming.

    He's not a customer, at best he's a guy with a broken car and I hope he realizes that he's not welcome at my place.
  • MrShift@EdmundsMrShift@Edmunds Posts: 43,629
    edited November 2012
    Here's a little explanation of the Buddhist idea of (pardon the translation, these are not my words) "idiot generosity".

    I never thought I would apply Buddhism psychology to running an auto repair shop, but you know, it kinda WORKS! :surprise:

    IDIOT GENEROSITY

    Basically there is nothing 'mystical' about this advice seems to me---you could re-word it, change the Buddhist nun to a guy in a white shop coat, and publish it in an auto repair Trade Journal. It's about handling people while handling your own welfare.

    A repair shop owner is like one of those guys at a carnival in a cage hanging above a water tank---every customer is trying to hit the bulls-eye.
  • isellhondasisellhondas Issaquah WashingtonPosts: 17,346
    There will always be a small percentage of customers you simply don't want. It's a small percentage but a business has to know when to tell these people to go elsewhere.

    These are the people who will blame a new scratch on the shop or tell you " It never leaked transmission fluid until you worked on the brakes...you MUST have done something"
  • thecardoc3thecardoc3 Posts: 1,521
    A repair shop owner is like one of those guys at a carnival in a cage hanging above a water tank---every customer is trying to hit the bulls-eye.

    We are fortunate to have a core group of customers who carry our shop year after year and they don't do the kinds of things that force us to split our concentration when it comes to servicing their vehicles. The ones who come in looking to take advantage of us cause us to have to keep looking over our shoulder to ward off the surprise complaint instead of getting to enjoy fixing their car. Even then, we usually get the task done perfectly, only to still see them unsatisfied.
  • thecardoc3thecardoc3 Posts: 1,521
    There will always be a small percentage of customers you simply don't want. It's a small percentage but a business has to know when to tell these people to go elsewhere.

    There are some businesses in this trade who cater to those people at a level that they reward them for acting like selfish spoiled brats. They still can't make them happy and at the same time teach them to try and take advantage of everyone they meet. That's exactly what the guy with the Cadillac did back then and even when he basically stole from us, it was in his eye's our fault.

    Frankly if he would have kept his mouth shut, I easily would have had him bring his Corvette in and repaired it for him. I don't recall names and faces and had easily forgot who he was. Yet I recall everything about individual repair events and the moment he mentioned his Cadillac it was total recall and I knew that he is poison.
  • andre1969andre1969 Posts: 21,577
    I have had cars that the owner stopped making the payment on and get repo'ed that we had a repair waiting to be paid for. We have been ripped off for quite a sizeable amount of money that way through the years.

    I think something along those lines happened to my previous mechanic. Back in December 2009, I noticed an '85 or older Buick Riviera sitting in their fenced-in back lot. A month or so later I noticed it was still there, and asked about it. The mechanic said it belonged to a woman who, after they did all the repairs (forget now what all was done), decided it was too much, didn't pay for it, so they kept the car.

    It's nearly three years later, and the last time I was in there, they STILL had the car! In fact, they still start it up every once in awhile to give it a run...which IMO is awfully nice of them.

    I wonder what would ultimately happen to a car like that? I'll confess to having a fascination of cars from that era, so the mechanic let me look at it one day. Too rough though, even for my tastes!

    I'm in Maryland, and have no idea what the laws are covering something like that.
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