4-CYCLE OVERHEAD VALVE ENGINES - Small Engine Discount

LOW OIL PRESSURE SENSOR
Test the sensor on a running engine using an
ohmmeter or continuity tester with one tester lead
connected the sensor terminal (with lead wire
removed) and the other to an engine ground. An open
circuit should be found with the engine running and
continuity should exist when the engine is shut off. If
continuity is found or the tractor oil pressure indicator
light is on or comes on at low engine RPM's, remove
the sensor and check engine oil pressure with a
master oil pressure gauge. The oil pressure of a
running engine should be above 10 p.s.i. (.700 bar).
If lower than 10 p.s.i. (.700 bar), an internal engine
problem exists (diag. 29).
LOW OIL SENSOR
This sensor must use a # 194 bulb in series with the
sensor for proper operation and to prevent sensor
damage. Remove the sensor from the engine and
attach the electrical plug. Attach a jumper lead from
an engine ground to the threaded portion of the
sensor. Place the keyswitch in the run position. The
indicator light should come on with the tip of the sensor
in air and go off when oil covers the sensor tip. The
response time of the sensor is between 5 and 15
seconds with 13 volts D.C. at the battery. Lower
battery voltage will result in a longer response time.
Use teflon-type pipe sealant on the sensor threads to
prevent oil leakage when reinstalling (diag. 30).
ELECTRIC STARTER SERVICE
This section covers the service procedures for the 12 and 120 volt electric starters. For diagnosis of the
starting circuit see “Electrical Starter Troubleshooting” in this chapter. Illustrations may not be identical in
configuration to the starter being serviced, but procedures and tests apply unless otherwise stated. Starters
labeled UL listed/ CSA approved are serviceable. Starters labeled CSA cannot be serviced, only replaced. If a
starter is serviced, the "O" rings on each end of the housing must be replaced.
12 VOLT or 120 VOLT ELECTRIC STARTERS
1. Remove the plastic dust cover on the bendix
end (diag. 31).
48
2. Push down the spring retainer and remove
the retainer ring.
3. Slide off the spring retainer, anti-drift spring,
gear, and drive nut.
4. If internal service is necessary (non-CSA)
starters only, scribe a line across the cap
assemblies and armature housing to aid in
reassembly.
5. Remove the two or four retaining nuts from
the through bolts holding the cap assembly.
6. Slide off the cap assembly. The terminal
insulator slides out of the commutator cap
(some models).
7. Remove the armature.
8. Inspect and replace as necessary, see the
section "Inspection and Repair" later in this
chapter. Use the reverse procedure for
assembly. ( For ease of assembly, place the
armature into the brush end of the frame first.)
BRUSHES
RETAINER &
SPRING
ARMATURE
BENDIX ASSEMBLY
RETAINING RING
DUST COVER
Not For Resale
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30
GASKET
29
THRUST
WASHER
31