Ask the Pros

Question: As a school bus fleet supervisor, I am trying to convince all of my technicians to become ASE certified. However, since several of them have been away from the classroom for many years, they are concerned about taking tests and the chance of failure. What can I as a supervisor do to help ensure success for my employees?

Marshall Casey: Remind your technicians that while this certification does require taking tests, these tests were all written by people in the school bus industry. This means that the information used in writing the questions came from people like themselves who earn their living by maintaining, operating or manufacturing school buses.

Begin by identifying which certification each technician wants to achieve first. My advice is to let the individuals make the decisions, since the first attempt should be in the area that the technician feels most knowledgeable. Regardless of which area they chose, if they have success with the first test, they will feel much better about working for the others.

Next begin to prepare well in advance of the test date. Taking certification exams is similar to athletic events; success seldom comes without proper preparation. Now I don't necessarily mean they have to study like students in the classroom, but they will need to be able to relate their day-to-day experiences on a different level. Sure they know how to diagnose and repair a particular component on a bus, but do they really understand why a certain procedure does or does not work?

This is where you can help. Ask questions such as "Why did you do this?" or "What happens if you do that?" Many shop repair procedures are hand-me-downs that have been passed along from other technicians, providing no explanations of the basic principles. By encouraging your technicians to think more about the things they do every day from habit, you will increase their understanding and awareness of repair procedures. Another technique that I have seen work well is to have the technicians quiz each other and openly discuss their thoughts and answers. These discussions usually prompt more detailed questions, which usually lead to a more in-depth discussion of the subject matter. This type of information-sharing will improve the knowledge and skills of all involved.

You should also contact ASE to receive copies of their preparation guides. This will give the technicians an idea of the types and format of the questions that will be found on their exams. Many technicians find difficulty in answering the "Mechanic A said this, Mechanic B said that, Who is right?" type questions. This is where they will really need to think things through. You will also find other study guides available for purchase that will provide study material and sample questions..

Question: A driver radioed our maintenance facility, stating that something under the bus (Type D-RE) had made a loud exploding noise like a tire bursting. After bringing the bus to a stop, he found that all of the tires seemed to be fine. The bus operated as normal with no sign of any problem, so the bus was brought to the garage. When the mechanics began checking for the source of the noise, they discovered an expanded fuel tank and a split rubber hose used to connect the tank and the fuel filler neck. The engine (CAT 3116) runs fine with no skipping or hesitation. Can you give us advice on what may have caused these conditions?

Marshall Casey: In relating your problem to a similar instance with our fleet, we found a problem with the #6 injector sleeve. The 3115 engine utilizes unit injectors positioned in sleeves inside the head with a fuel galley supplying the fuel. If the seal between the sleeve and the head is defective, it can allow combustion pressure to escape into the fuel galley. By this occurring on No.6 cylinder, the combustion pressure was going into the return side of the fuel. This does not cause a loss of fuel to the injector and therefore the cylinder does not skip or misfire. It will create a substantial increase in pressure and aeration of fuel being returned to the tank. The typical tank vent is not capable of adequately relieving the pressure and, with a non-vented cap, overall tank pressure increases. This increase in pressure causes the rubber connecting hose on the filter neck to swell and burst. If this same problem happens to occur on a cylinder other than No.6, you will notice a misfire in the engine with any cylinders located downstream.

Source: School Bus Technician, May, 1999