Investigation
of a number of engine failures due to bearing failures and abnormal
cylinder wall and piston ring wear has been traced to abrasives
by-passing the filter element in the oil filler and breather
cap assembly.
FILTERS
A filter, located in each rocker arm
cover, contains a paper element (Hastings replacement part
number CB-7). This element should be replaced after each 4000
miles when the vehicle is operated under normal conditions.
When the vehicle is operated in extremely dusty conditions
the element should be replaced at 1000 mile intervals, or
more often.
Inspection of cap assemblies removed
from failed engines revealed that the filtering element sealing
surface of the lower section of the cap assembly had been
bent and distorted by service personnel using a tool to pry
the cap off the rocker arm cover. The distorted cap will allow
air gaps between the filter element and the sealing surface
and permit abrasives to enter the engine.
In some case removal of the cap can
be difficult. However, tight fitting caps can be removed by
rotating the cap and pulling upward at the same time. IT IS
EXTREMELY IMPORTANT THAT THE CAPS NOT BE PRIED OFF WITH A
TOOL BECAUSE OF THE SERIOUS PROBLEMS THAT CAN RESULT.
TUBE-TYPE CRANKCASE
VENTILATION SYSTEM
The ventilation tube contains a filtering
element which is serviced as follows:
1. Remove crankcase ventilation tube
lower extension by loosening the retainer bolt and turning
the tube to disengage the slot.
2. Remove the vent tube filter with
pliers, DO NOT ATTEMPT TO DRIVE IT OUT AS THIS WILL DAMAGE
THE FILTER.
3. Clean the filter with solvent and
dry it with compressed air.
4. Install
the filter and crankcase ventilation tube lower extension.
POSITIVE CRANKCASE
VENTILATION SYSTEM
At 8000 miles or more often, remove
the crankcase regulator valve, exhaust tube, and connections.
Clean the valve and exhaust tube in clean carburetor solvent
and dry with compressed air. Clean the rubber hose connections
with a low volatile petroleum base solvent and dry them with
compressed air.
EXCESSIVE OIL CONSUMPTION CHECK FOR
THE 401, 477, AND 534 CUBIC INCH FORD TRUCK ENGINE
When excessive oil consumption on low
mileage or rebuilt engines occurs, a check should be made
to see that the rubber drainback oil tube, which is located
in the push-rod chamber, is properly positioned. (See Fig.
1) If the tube is not properly positioned on the ventilation
tube attaching nipple, the tube can distort if it comes in
contact with the cylinder block casting. This will trap the
oil preventing drainback into the engine-causing the engine
either to consume oil through the P.C.V. system, or force
it through the road draft tube, if the engine is so equipped.
To make a thorough and positive inspection
to see that the oil drainback rubber tube is not restricted,
the valve push-rod chamber cover should be removed and the
rubber tube examined. The rubber tube then should be re-positioned,
making sure that the passage of oil will not be restricted.
