Two Diesel Fleet Truck Fires a Month Apart, West Texas (2019)

In 2019 a fleet owner asked us to investigate two of its diesel trucks that had burned on highways in West Texas about a month apart. Client details are confidential.

One fleet, two sets of evidence

We examined both trucks at a fleet yard, reviewed their maintenance records and studied photographs taken at each scene. In both cases the driver saw smoke while driving, with no warning light or sign of a mechanical problem beforehand. That is where the similarity ended.

The first truck

A photograph from the scene showed the engine compartment burning and the fire spreading toward the cab, with the wind blowing from the rear of the truck toward the front, which slowed the spread backward. On the truck itself, the engine compartment had the heaviest damage. Damage decreased from the top of the engine toward the bottom, where painted surfaces were barely affected and the belts were still in place. The batteries, under the steps on the right side, were in good condition, as were the exhaust system and the transmission.

On the left side of the engine, the hose connection at the top of the fuel water separator was missing its screw clamp. The hose still carried the indentations where a clamp had been. Without the clamp, fuel could escape from the connection as a fine spray onto hot engine parts. We placed the point of origin at the top of the separator, identified the first fuel as atomized diesel and the ignition source as hot engine components.

The second truck

The second truck was almost fully involved before the fire was put out, with all six tires burning and a hole in the top of the fuel tank feeding the fire. Aluminum at the front had melted, and the right side of the engine was severely damaged. The driver had seen white smoke from the exhaust, then fire under the engine and something dripping that made it grow. Too little was left to support an origin or a cause, and the report said so instead of borrowing the answer from the first truck.

Two fires are not a pattern by default

When one fleet loses two trucks in a month, it is natural to look for a single cause. Each fire still has to be worked from its own evidence. Our vehicle fire investigations follow that rule. Fleet owners can send a loss through the forensic assignment form.