I agree with what Terry said and am going to paraphrase his statement to hopefully show you how valuable I find his words.
Become a
diagnostician instead of a parts-changer. You can have all the books in the world and the best tools available, but they won't help you if you can't accurately and efficiently
diagnose a problem. Most people are parts-changers, yet think they are competent mechanics. When people ask me to help with their vehicles, they usually becoming frustrated with me because I refuse to use their parts-changing methods. They want me to use their methods of repair in hopes of getting better results, but it doesn't work that way. When I cut corners and use their methods, I get their results. When I take the time to use my methods, I get my results. While it takes more brain work and more time to properly diagnose a vehicle, it results in less frustration, less money spent, and an overall shorter length of time to repair a vehicle that will stay in a state of repair for a usually much longer period of time. An example:
A lady was having problems with her 92 Blazer. We spoke about it and she diagnosed it enough to know it was likely a fuel issue. She thought it was the fuel pump, but I told her I didn't know if it was or not, but that it was likely. She thought that was good enough and changed out the pump, which was labor intensive. The next day she was happy that it was running well, but 3 days later it started having the same problems again. She said she must have purchased a bad fuel pump. I told her I doubted she had purchased a faulty fuel pump, and that something else was causing problems. I asked her if she checked the fuel filter; she said no. Told her to replace it since it was cheap and part of maintenance anyway, so diagnosing the fuel filter wasn't necessary. I asked if she had tested the fuel pressure and she said no. I lent her my tester and the pressure tested very low. She figured the new fuel pump was bad from the start. I again voiced my disagreement, and emphasized that she needed to test the voltage WITH A MULITMETER (a load tester is really what was needed, but not everyone has all the diagnostic equipment that is needed) as a possible cause of failure.
A couple days later she replaced the pump again and was super happy it was working. A few days later the Blazer started running poorly and quit running again. I asked her if she had tested if 12 volts was getting to her pump. She said she used a test light and showed it was getting voltage, so that was good enough for her. I told her she is wasting her time and that she is unnecessarily spending her time and money when she doesn't know what the problem is. I reiterated that she needed to test the voltage because there is a reason that pump is failing. She kind of was getting tired of me answering her questions that did not agree with her answers. I told her it was asinine to keep doing the same thing and expect the same results and to keep ignoring the advice of an experienced and trained mechanic. (Can you tell I was getting tired of this? :huh:
) She kind of said OK, but she was just blowing me off, which was fine with me. When it failed again, I asked if she had used a multimeter or a voltmeter. She said no.
Was low or high voltage causing the pump to burn out? I don't know. There was a reason it failed and she chose not to find that reason. While she didn't have access to all the diagnostic tools to perform a truly professional diagnosis, she very likely could have found the problem(s) and fixed it properly with the tools she did have access to. If you want to treat a problem symptomatically and keep putting Band-Aids on the problem, you will not truly fix the problem. Look for the
core issues and do so in a systematic way by diagnosing the real problem. This is goes a long way towards being a true mechanic.