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A Mechanic's Life - Tales From Under the Hood

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  • obyoneobyone Posts: 8,065
    About $10,000 in difference......

    While I believe in the quality of snap on tools. Their low speed (hand crank) balancer leaves much to be desired. While I have successfully balanced tires using the Snap on balancer at times the results were inconsistent. In other words customers have returned with vibrations that they didn't have prior to coming to the shop.

    I understand the $10K price difference and it appears you don't specialize in tires making the Hunter 9700 difficult to justify. I'm just wondering if there are better balancers out there for the $4K paid for Snap on's version.
  • thecardoc3thecardoc3 Posts: 1,521
    He also says that Audi assured him a number of times that the car is completely within spec.

    Just getting it "in the green" isn't always good enough. Today's alignment machines produce a print out of the specs, and the current settings. I need to see the specs. Today many cars don't come with full adjustment capability, and it comes down to aftermarket solutions to make full adjustments.

    Scrub radius (wheel offset) issues can cause some tire wear complaints but the bigger problem comes down to improper loading and subsequent hub or wheel bearing wear.
  • thecardoc3thecardoc3 Posts: 1,521
    While I believe in the quality of snap on tools. Their low speed (hand crank) balancer leaves much to be desired.

    With wheels that mount up correctly it's "fine" mode allows me to balance the assembly dynamically to within two grams.

    The problem comes down to wheel designs that just refuse to cleanly mount with the available centering cones. The balance, then reposition and recheck routine catches the problem wheels all the time. The trick then is to be patient and see if a solution can be arrived at, one wheel at a time.

    As far as justifying a $14,000 balancer, I can't really justify owning the $4000 one, I'm a driveability/electronics/repair shop and have no employee's. I wouldn't sell enough tires in a month to even make enough gross profit to cover the payment on a new balancer.
  • thecardoc3thecardoc3 Posts: 1,521
    Next to him was the Hawaiian Punch funny car. A quick peek revealed...guess what....a bubble balancer.

    http://www.hotrod.com/thehistoryof/retrospective/hrdp_1005_getting_to_know_rolan- d_leong/photo_16.html

    Enuogh said.... :shades:
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,913
    it comes down to aftermarket solutions to make full adjustments

    You mean the BIG hammer? :D
  • On some cars (trucks and vans) you bend the axle with hydraulic power. :)

    This wouldn't be the first time someone decided to take a hammer to an Audi.
  • thecardoc3thecardoc3 Posts: 1,521
    This wouldn't be the first time someone decided to take a hammer to an Audi.

    LOl, this could get out of control in a hurry...
  • obyoneobyone Posts: 8,065
    image

    That's the car that had it's tires balanced on a bubble balancer.
  • thecardoc3thecardoc3 Posts: 1,521
    This was a first time customer who was referred to us. He's been dealing with a repeated check engine light for more than a year and it always came up with the code description for a large evaporative emissions leak. It's had no less than three gas caps put on it, several smoke tests, the canister vent valve has been replaced and every time the light simply came right back on in a couple of days.

    When diagnosing any evap failure, the first step is to understand the particular system that is on the car you need to diagnose, and how the car's computer tests the system. Then you can start testing the system just like the computer on the car does.

    From "an instructors" point of view the pull a code and guess a part approach fails the moment that no effort is put into trying to understand how the system works. For this customer, three parts stores pulled the code and all three sold him a gas cap. On a second visit to one of them he was sold the canister vent valve.

    He went to several shops requesting a smoke test of the system. A smoke test uses a pressurized system to pump smoke into the fuel tank and the carbon cannister and it's hoses and lines. If the system has a leak, the smoke shows where it's at. (most of the time) The smoke tests could not locate a leak.

    He came to my shop requesting a smoke test, I told him a better approach would be to simply allow us to diagnose the problem, and I would use my smoke machine as part of that process if necessary.

    He agreed to that approach.

    As I mentioned, the first step is to be sure that you understand the system. The second step of the diagnostics is to attach a scan tool, retrieve the code and begin the process of testing the system. You must do this while forgetting everything else that you have been told has been checked/replaced/tested. (Any ideas why I mentioned that right here?)

    What is the next step and why?

    How would you proceed with testing this system to repair the problem?

    BTW, it was really refreshing to have this customer be appreciative for us solving this problem for him.
  • thecardoc3thecardoc3 Posts: 1,521
    Yes, I remember it. The link was the owner of that car instructing another driver about how to drive through wheel shake. :shades:
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,913
    What is the next step and why?

    Go to the Chevy dealer and buy an OEM gas cap and quit using aftermarket ones from the auto parts stores. :D
  • thecardoc3thecardoc3 Posts: 1,521
    Go to the Chevy dealer and buy an OEM gas cap and quit using aftermarket ones from the auto parts stores.

    All kidding aside, that of course would have only cost the owner more money and you just added yourself to the list of people who failed to give this owner an answer, the first time that you looked at the car.

    This is a real case study, either you know the correct proceedure to diagnose the car, or you don't.
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,913
    edited December 2012
    Although, per forum posts here over the years, that option has "fixed" quite a few recurring CEL problems for people.
  • thecardoc3thecardoc3 Posts: 1,521
    Although, per forum posts here over the years, that option has "fixed" quite a few recurring CEL problems for people.

    That mistaken belief is one of the reasons why I (or at least someone who really does know better) should have been around here a long time ago.
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,913
    edited December 2012
    It's pretty simple from the point of view from the other side of the counter.

    The most common reason for a CEL coming on is a loose gas cap. If tightening that doesn't work the next step I'd take is to get on the net and find the bad cap and O2 sensor posts. Then I'd go buy an OEM gas cap. If that doesn't work, I'd take it back to the dealer and get my money back (less a 20% restocking fee perhaps). So far I'm out my time and maybe $4 and some gas or shipping costs). Big whoop. If it works I'm golden.

    If the easy stuff fails I look for real help (since 02 sensors can be pricey and typically can't be returned as easily as non-electrical parts).
  • thecardoc3thecardoc3 Posts: 1,521
    Then I'd go buy an OEM gas cap. If that doesn't work, I'd take it back to the dealer and get my money back (less a 20% restocking fee perhaps)

    So then if they try to sell it to the next person and they realize that it's already been enjoyed once by someone else and they get upset because they have been sold a "used part" instead of a "new one". In that customers eye's someone is being a theif and ripping them off.

    It's pretty simple from the point of view from the other side of the counter

    Yea, you might just as well keep the new cap and out your old one back in the box to return.... That's how it would look to another customer on your side of the counter. That's how it would look to you if you opened the box and found the cap you just bought had already been tried.

    In real numbers, barely 1% of evap failures are caused by faulty gas caps, claiming anything else is intentionally misleading to the consumer. Now why would you want to do that?

    Loose caps are caught by the systems because today they run a specific series of tests that are triggered by an increase in the level in the fuel tank.

    You have said numerous times that you want the cars to be able to 'self diagnose" more completely and to a certain extent that has happened. They have managed to make it pretty cut and dry how diagnostics should be performed and just how obvious blind guesses by untrained individuals are nothing more than that.

    Feel free to admitt that you have no clue about how to really approach this anytime. The sad part is, what I use is a very simple, repeatable routine that has a technician arrive at the correct answer THE FIRST TIME, and EVERY TIME, no matter where the failure is. Guess you should be able to see why it was somewhat refreshing to have had a customer that was glad we were there to help him.
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,267
    (Any ideas why I mentioned that right here?)

    Make assumptions that something isn't a problem because it was already tested/replaced, and you're going to make the whole process that much more difficult for yourself.

    What is the next step and why?

    Assuming an understanding of the system (which you noted as step 1), I'd say that the next step is to replicate conditions that should cause that DTC to set, in order to verify that the OBD system is working correctly.

    How would you proceed with testing this system to repair the problem?

    Then, I'd test the parts of the system that fed into it to determine which part(s) was(were) out of spec.

    Sorry, but since I haven't a clue how that system is looped, I can't get any more specific than that.

    ---

    I'm curious about two things (in addition to your general solution methodology & the actual problem in this case): 1. How long did it take to diagnose, and then fix, the issue, and 2. Appx. much did the customer end up paying?

    I'm glad to hear that the customer was appreciative in this case. He tried the other method, failed, and knew it was time for something better! :shades:
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,913
    edited December 2012
    I take "used" stuff back all the time and store repackage and resell it all the time. Go in to the back of most any store and you'll see a shrinkwrap machine they expressly use for this purpose. Bit of a red herring issue; if a parts store doesn't want parts returned, they can post a sign and not accept returns, and check boxes when they do take returns and make sure the part isn't scratched and dinged.

    In real numbers, barely 1% of evap failures are caused by faulty gas caps, claiming anything else is intentionally misleading to the consumer. Now why would you want to do that?

    In the real world many CEL lights come on because of loose gas caps. A $20 exercise at AutoZone or NAPA is cheaper than going to the shop.

    If a customer called you and said their CEL was on but they couldn't stop by your shop for 3 days, would you tell them to check their gas cap and perhaps ask them when someone last filled up the car?

    (As an aside, did you see where the most recent Ford recall for potential engine fires is going to be addressed by a software fix?).
  • thecardoc3thecardoc3 Posts: 1,521
    I take "used" stuff back all the time and store repackage and resell it all the time

    Many returned items never make it back to a stores shelves. Too much of a risk of dissapointing the next customer. These items need to be sent back to the manufacturer who can inspect them, and then they must use another routine to re-release them or else just scrap them.

    In the real world many CEL lights come on because of loose gas caps. A $20 exercise at AutoZone or NAPA is cheaper than going to the shop.

    Not anymore they don't. My 2002 Ford Explorer has a check fuel cap light that is seperate from the check engine light. When you refuel that car (and many others just like it) the computer runs the large leak test and compares that result to stored test results from previous tests. The system then knows for certain if the newest result is different from previous test results and in the case of my Explorer would turn on the loose cap light and not store a pending code for the evap system. Now the next time the test runs and it detects a leak, then the system stores the pending code. Then only after the third time the test would find a leak it sets the gross leak code and now turns the light on.

    Cars not equippped with the loose cap light set a specific code for a large leak, seperate from the SAE code and again it's because of weighted testing results that are compared to previous tests.

    If a customer called you and said their CEL was on but they couldn't stop by your shop for 3 days, would you tell them to check their gas cap and perhaps ask them when someone last filled up the car?

    No. The questions that I am going to ask are:
    Is the car running normally? Are you having any trouble with it running rough, stalling, difficult to start or is or has the check engine light been flashing?

    The moment someone touches the cap once the light has come on, the only thing that they really accomplish is make it impossible to prove if the cap's being loose caused the light to be on. To a technician it ends up being an intermittent failure condition and you can only assume the cap must have been loose, you don't actually know for certain if it was or was not.

    By touching the cap, and now we get a "no trouble found" it's quite common for the light to come back on within the next few weeks and now it's "a second trip back to the shop" because they didn't fix it the first time.

    BTW, with some cars that have ORVR (on-board refueling vapor recovery) systems you can leave the cap completely off and it doesn't care because the filler neck is sealed off down below closer to the tank. Cars that test themselves with pressure cannot test the filler neck with an ORVR system and it makes for a nice little puzzle for the technicians when I do as a hands on portion of an evap class that I teach. We make the monitor run with the gas cap off of the car and it passes. This does not work with cars that use vacuum to test themselves, they will catch the cap loose/missing.

    As an aside, did you see where the most recent Ford recall for potential engine fires is going to be addressed by a software fix?.

    No, haven't paid any attention to that at all. First we don't do recalls as an independent. The reflashes that we do but are totally software driven and pretty much a hands off operations outside of telling the computer yes, do the reflash and then exercising the ignition switch as the system commands.
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