The relationship of maintenance to vehicle fires

Mike Higgins
K-Chem Labs
Westford, Massachusetts

The quality of maintaining a vehicle can directly affect the possibility of having a fire occur at some point in the future. Having examined hundreds of vehicles over the past twenty years to determine the origin and cause of fires, I have found the lack of good maintenance to be one of the major causes of vehicle fires. This is closely followed by poor maintenance where the work has been completed by unqualified or sloppy technicians. The size and type of vehicle doesn't seem to matter—when it comes to poor workmanship, fires will occur.

This truck burned as a result of a replaced hydraulic line causing the main power feed to the cab to be forced against the rail. Vibration and time broke down the insulation and the resulting short started the fire.

The cause of these fires can be directly related to the use. Vehicles and trucks that are driven less than fifty thousand miles a year may be more susceptible to accidental fires than those on the highway traveling in excess of one hundred fifty thousand miles a year. Rough terrain and heavy stop and start use cause a great deal of vibration, which in turn causes parts to work loose and components to rub or wear against each other.

When it comes to the electrical system one must understand that the insulating components of wires in most cases are synthetic and probably made of vinyl. This is a relatively soft material that can easily be worn through by rubbing against other components, even another wire, or will melt when placed against hot surfaces. The majority of the wires in vehicles are processed through pre-wired harnesses that prevent friction problems; however, this all changes when it comes to larger gage wire such as battery cables, alternator wires, and after-market wiring for added accessories.

Larger gage wire is frequently tied to hoses, other harnesses, and the engine block or to the frame. In most cases if these lines are left alone nothing will ever occur that may cause a fire. But in the real world we know that replacing and/or maintaining various components often requires that the tie-downs for these cables be cut loose or totally disconnected.

Problems begin to occur when these wires are not rerouted and tied down properly as prescribed by the vehicle manufacturer. Loose wire connections with a heavy load can overheat to the point where the insulation will melt and then ignite. While it is true that wire insulation contains flame retardants, these retardants typically "cook out" when the wire is heated, leaving a virgin plastic that is very flammable.

Components such as starters that are heavy and located in very tight places routinely cause problems that can lead to fire. Many fires occur when the wire is not properly routed and tied down. Time and vibration will also break down the insulation and cause shorting to the frame or other wires.

Fuel and hydraulic lines can wear and vibrate loose, causing leaks. When coming in contact with hot surfaces these petroleum products can and will ignite. Vehicles that run on gasoline have engines that run much hotter than diesel. Manifolds on these vehicles can reach temperatures in excess of 1,000 degrees Fahrenheit. This temperature can auto-ignite oil, gasoline, hydraulic fluid and brake fluid. Vehicles that require brake fluid can have a fire occur in the wheels if fluid leaks onto the drums or disk. Brake disks or drums can also reach temperatures in excess of 1,000 degrees Fahrenheit and will easily ignite the leaking brake fluid.

Not every vehicle will burn if the wires develop a short or a fluid leak occurs, but when they do, too often it can be traced back to a maintenance or repair issue. Make sure it is not one of your vehicles that burns. Take a little extra time and tie down the wires or cables that had to be cut, tighten all of your connections, and put in new gaskets to prevent fluid leaks. And make certain that component parts are reinstalled to the original manufacturer specifications. When fires occur it is never the right time or place, especially when you know they could have been prevented.

Mike Higgins can be reached at (978) 392-9034 or at