LUBRICATING SYSTEM MAINTENANCE
certain lubricating system service jobs that are more or less done automatically when an
engine is repaired. For example, the oil pan is removed and cleaned during such engine
overhaul jobs as replacing bearing or rings. When the crankshaft is removed, it is usual
procedure to clean out the oil passages in the crankshaft. Also, the oil passages in the
cylinder block should be cleaned out as part of the overhaul.
Construction Mechanic, you will be required to maintain the lubrication system. This
maintenance normally consists of changing the oil and filter(s).
you will be required to perform such maintenance tasks as replacing lines and fittings,
servicing or replacing the oil pump and relief valve, and flushing the system. The
following discussion provides information that will aid you in carrying out these duties.
It is extremely important that the oil and filter(s) of the engine are serviced
regularly. Lack of oil and filter maintenance will greatly shorten engine service life.
give a maximum number of miles or hours a vehicle can be operated between oil changes.
Newer automotive vehicles can be operated 5,000 miles between changes. Older automotive
vehicles should have their oil changed about every 3,000 miles. Most construction
equipment average between 200 and 250 hours of operation between oil changes. However,
depending on the climate and working conditions the 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.
drain plug and allow the oil to flow into a catchment pan Be careful of hot oil; it can
cause painful burns.
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.
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 and leak.
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.
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 salvage.
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
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 starting.
pump in reverse order of removal. Anew gasket should be used and the retaining bolts
torqued as specified by the service manual.
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.
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.
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 tension.
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.
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.
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 relief valve.