School bus repairs in the garage are different every day. The mechanic has to be prepared to diagnose and repair problems in various categories like electrical, air brakes, steering, engines and emissions. I’ve seen problems happen in groups of three and within a tight time frame. This isn’t surprising since every group of buses purchased per year has the exact same specifications.
Air brakes are a constant repair. They are worked hard every day with stop and go driving. They don’t have a heavy load like a transport truck but still have to stand up to expansion and contraction along with different loads and speeds. The bus I covered in the video getting a brake job was due for a complete rear axle brake component replacement. Everything gets a look over on top of shoes and linings. The spring brake chambers and slack adjusters are replaced every 5 years.
It’s amazing how cheap brake parts are sold for these days. You can buy a relined 7 inch wide rear brake shoe for $23.00 and the common brake drum for those shoes go for $80.00. The spring brake chambers will sell for less than $40.00 each. MGM products are superior than the other brands so for an extra 20 bucks each it’s an easy decision. Long stroke brake chambers are a nice addition to modern air brake systems because of the extra 1/2 inch of brake stroke allowed.
The Navistar conventional bus with the coolant leak in the cab has happened to 3 buses… same year and specs. Every Navistar bus we have in the fleet (18 total) have this hose and for some reason only this one year have given us grief. When the hose blows it leaks in the cab all over the floor. If the driver can run out to lift the engine hood and turn off the coolant shut off valves to the cab they may be able to drive back to home base.
The diesel engine we’re repairing is torn apart waiting for parts. Bummer…that’s a frustrating thing that you have to deal with. Normally I like to have all of the parts in my hands before beginning the dis-assembly. In this case we found more trouble along the way and had to re-order which causes a delay. The downtime has been excessive on this job but you can’t predict what you’re going to find and fleet operators realize this.
The last job on the Chevy van is all about the park brake not holding according to the commercial vehicle inspector. The driver was stopped for excessive speed on a back road and the inspector did a complete inspection. The park brake failed for not holding. The inspection manual states that with the parking brake applied and the transmission in drive at 800 rpm the brake needs to hold. I think what happened is the inspector told the driver to hit the throttle. With disc brakes on the back wheels and the tiny drum / shoes making up the parking brake there is no way it will hold.
Regardless…. we replaced the park brake shoes and checked the other components. It just needs a re-inspection. I’m sure it will pass with new linings and a tighter adjustment. These are some typical jobs that we deal with on a school bus fleet. The mechanics are kept busy and have to always be on their toes.
