Claims handlers are often charged with determin- ing if an automotive engine failure is a result of an impact with an object or a result of an internal problem that caused the damage, typically called
mechanical failure. Many policies are written to extend coverage
when the vehicle impacts an object causing damage to the engine, while coverage is denied if an internal malfunction causes
damage to the engine. Figure 1 is a view of a penetration in an
engine block that was claimed to be caused by an external object
striking the engine.
Figure 2 is a view of a typical engine. Penetrations in the block
area shown by the upper arrow are typically the result of an internal engine problem such as connecting rod or piston failure.
The engine block is higher up in the vehicle engine compartment and less vulnerable to penetration by an object found on
the road. A penetration at the oil pan can be a result of impact
with a road object as this is an area that is low and close to the
road on a vehicle.
Figure 3 is a view of an engine mounted in longitudinal fashion — the crankshaft is parallel to the long axis of the vehicle.
The lower arrow points to the oil pan which is more vulnerable
to road object impact than the engine block as indicated by the
Figure 4 shows a transverse mounted engine — the engine
crankshaft is perpendicular to the long axis of the vehicle. The
lower arrow points to the oil pan which is vulnerable to road object impact, while the engine block is well protected as indicated
by the upper, right arrow.
Going back to Figure 1, the penetration is at the engine block
near a connecting rod in an area that would be difficult for a road
object to penetrate without leaving any other evidence of impact,
such as scraping. The shape of the penetration presents fracture
surfaces that angle outward, which is characteristic of a penetration that came from within the engine.
Figure 5 is a view of an oil pan showing impact damage to
the lower portion — a crease in the metal. This did not cause a
leak or interfere with any engine components and did not cause
the engine failure. Oil analysis showed high internal metallic
contact, suggesting that the failure was a result of engine wear
brought on by poor maintenance.
Figure 6 shows an oil pan that sustained an impact with an
external object, causing a severe inward deformation of the front
of the oil pan. The deformation interfered with the crankshaft,
which wore an opening in the pan, expelling oil and causing
loss of oil pressure in the engine, leading to a failure. Some oil
pans on vehicles with low clearance are vulnerable to road object
impact. When this occurs, engine oil is expelled, which can be
detected when the low oil pressure warning occurs on the instru-
ment panel. There are circumstances when the penetration or
deformation occurs from a road object where there is relatively
little damage to the engine, if it is shut off immediately. If the
vehicle continues to be driven after such an event, severe damage
to the engine from a lack of oil pressure may occur.
When a penetration to an engine occurs at the engine block,
it is likely a result of an internal problem with the engine. When
this occurs at the oil pan, there is a possibility that the penetration was caused by an object in the road. Analysis of the deformation to the oil pan will help determine if an external or internal object caused the failure. Fracture surface and oil analyses
will also aid in the determination of a wear out or maintenance
Charles C. Roberts, Jr., is president of C. Roberts Consulting
Engineers, Inc., which provides professional engineering
services in accident reconstruction, failure analysis, fire
causation, explosion analysis, and biomechanics. He may be
reached at firstname.lastname@example.org.