Lesson 3/Learning Event 1
Most of the time, coolant leaking onto hot engine parts, such as the cylinder block, can be detected by rusty
colored streaks in the area of the leak. The coolant runs onto the parts and, due to the heat, it boils away
leaving a rusty stain. Be sure to look for stains like this where the head and the block join. Sometimes this is
the only way a head gasket leak is discovered.
Some coolant leaks will only show up when the engine is running or after it has been warmed up. When the
engine is running and warm, the coolant is under pressure and may be forced out through small holes where it
may not leak otherwise. You must be very careful when inspecting an engine that is running to prevent
injuring yourself on the fan, belts, or other moving parts.
Check the mounting of all accessories for loose, cracked, and missing hardware, such as brackets, nuts, bolts,
and washers. Just normal operation, not to mention driving over rough roads, will cause nuts and bolts to
loosen and often fall completely off the vehicle. Make sure a note is made of all loose and missing bolts and
nuts so they are taken care of before they cause more damage.
During all phases of engine inspection, look for signs of overheating, such as holes in the engine block, cracks
in the block, and leaking water jacket plugs. Any of these items can either cause the engine to be unsuitable
for repair or indicate more damage that you cannot see. Bent or damaged parts attached to the engine indicate
that a closer inspection of the engine block is required. For instance, mounting pads or bolt holes may be
Does the engine start within the first few seconds of cranking? The vehicle batteries can only operate the
starter system for short time before they run down. Also, cranking the engine for long periods will overheat
the starter motor causing damage to it. If the engine is too hard to start, an engine tune-up may be needed.
Then again, the cause may be the engine is cranking too slow due to a faulty starter system or batteries that are
partially discharged. On the other hand, the piston rings may be worn or the valves may be leaking so the
compression pressures are too low.