miles and hours between oil changes can be greatly
reduced. Refer to the service manual for exact intervals.
To change the engine oil, warm the engine to full
operating temperature. This will help suspend debris in
the oil and make the oil drain more thoroughly.
Unscrew the drain plug and allow the oil to flow into a
catchment pan Be careful of hot oil; it can cause painful
Usually the filter elements are replaced at the same
time the oil is changed. The most common filters are the
spin-on filter or replaceable element type oil filter.
Spin-on, throwaway oil filterreplaced as a
complete unit. Unscrew the filter from the base
by hand or a filter wrench and throw the filter
away. When replacing, wipe the base clean with
a cloth and place a small amount of oil or grease
on the gasket to ensure a good seal. Screw on a
new filter, tightening at least a half a turn after the
gasket contacts the base. Do not use a filter
wrench because the filter canister could distort
Replaceable element oil filterremoved from
the filter housing and replaced. Place a pan
underneath the filter to catch oil from the filter.
Remove the fastening bolt and lift off the cover
or filter housing. Remove the gasket from the
cover or housing and throw it away. Take out the
old element and throw it away. Clean the inside
of the filter housing and cover it. Install a new
element and insert a new cover or housing gasket
(ensure the gasket is completely seated in the
recess). Replace the cover or housing and fasten
it to the center bolt securely.
After the oil has been completely drained and the
drain plug replaced, fill the crankcase to the full mark on
the dipstick with the proper grade and weight of oil.
Start and idle the engine. Check the oil pressure
immediately. Inspect the filter or filter housing for
leaks. Stop the engine and check the crankcase oil level
and add to the full mark.
Oil Pump Service
Service on oil pumps is limited since they are
relatively trouble-free. An oil pump will often still be
operating trouble-free when the vehicle is ready for
A bad oil pump will cause low or no oil pressure and
possibly severe engine damage. When inner parts wear,
the pump may leak and have a reduced output. The
pump shaft can also strip in the pump or distributor,
preventing pump operation
To replace the oil pump, it is first necessary to
determine its location. Some pumps are located inside
the engine oil pan Others are on the front of the engine
under a front cover or on the side of the engine. Since
removal procedures vary, refer to the manufacturers
service manual for instructions.
Most mechanics install a new or factory rebuilt
pump when needed. It is usually too costly to
completely rebuild an oil pump in the shop. Before
installation, prime (fill) the pump with engine oil. This
will assure proper initial operation upon engine
Install the pump in reverse order of removal. Anew
gasket should be used and the retaining bolts torqued as
specified by the service manual.
Pressure Relief Valve Service
A faulty pressure relief valve can produce oil
pressure problems. The valve may be located in the oil
pump, filter housing, or engine block.
If symptoms point to the pressure relief valve, it
should be disassembled and serviced. Cleaning and
adjusting is all that is usually required. Remove the cup
or cap, holding the pressure relief valve. Then, slide the
spring and piston out of their bore.
Measure the free length of the spring (length of
extended spring) and compare it to the specifications. If
the spring is too short or long, install a new spring.
Some manufacturers recommend checking spring
Use a micrometer and a small hole gauge to check
the valve and valve bore wear. Also, check the sides of
the valve for scratches or scoring. Replace the parts if
any problems are found.
Assemble the pressure relief valve. Make sure that
the valve is facing correctly in its bore. Slide the spring
into place. Install any shims and the cover plug or cap.
Refer to the service manual for details.
The pressure relief valve may be adjusted in one of
two ways. One way is by an adjusting screw (having a
jam or locknut) which adds or relives pressure on the
spring. The other way is by adjusting shims that are
added or removed to adjust opening pressure of the