Lesson 3/Learning Event 1
Oil leaks are most likely to appear where gaskets and oil lines connect to or touch other parts. Some places to
pay particular attention to are the valve covers, oil pressure sending units and safety switches, oil filter
mountings, all oil lines, and the crankcase oil pan. Keep in mind there is no place on an engine where oil is
supposed to leak.
You may ask, "Why should I be so concerned with oil leaks?" Well, the loss of oil cuts down on how far you
can travel with a vehicle before you have to stop for maintenance or service. Another reason is that dirt will
stick to oil and when oil and dirt cover an engine, the engine will overheat. An oil and dirt mixture will burn,
so it also gives fire a place to start. Therefore, you must be thorough; make sure all oil leaks are seen and
recorded, and then begin inspecting for other faults.
Before inspecting something other than oil, be sure you check the oil level in the crankcase. Usually, the main
reason anyone checks the oil level with the dipstick is to find out if there is too little or too much oil in the
crankcase. But, when inspecting an engine, there are other reasons too.
Suppose that the oil level is too high and has a milky appearance. The dipstick may also be rusty or show
drops of water. All of these things are caused by water getting into and mixing with the oil, making it unfit for
use. This means that you will have to find out how the water got into the crankcase, which may be through a
leaking head gasket or a cracked engine block or head.
On other occasions, you may find that the oil on the dipstick looks very dark and feels like it has sand in it.
This could be caused by the oil not being changed regularly and may indicate more serious trouble, such as
excessive wear of engine parts.
Looking for coolant leaks is like checking for oil leaks; make sure all points are covered. In fact, you can
combine these two checks and look for both coolant and oil leaks as you move around the engine. Be sure to
include the radiator and all connecting hoses when looking for coolant leaks.