Doosan DA40 - Engine speed hunting - single-speed engines with RQ governor; Engine speed hunting - single-speed engines with RSV governor

SHOP MANUAL
Engine
Ch 1 page 238
Engine speed hunting - single-speed engines with RQ governor
Engine speed hunting - single-speed engines with RSV governor
Eect Cause Trouble shooting Action
Hunting when
engine is running
under light load
(15 - 20 kW) or
no-load conditions
Play in exible cou-
pling between engine
and alternator (worn
coupling)
Apply a light load, at a
load of about 20 kW the
hunting disappears
- Change the rubber ele-
ment/check the cou-
pling hub and ange
Play in new coupling
- Choose a coupling
without play, e.g.
Scania standard cou-
pling
Not enough ywheel
mass in the driven unit,
e.g. alternator
- Mount extra ywheel
mass
Skew engine brackets
(engine suspension)
could under unfavoura-
ble circumstances
worsen engine speed
hunting
- Change to harder rub-
ber elements for the
engine/alternator sus-
pension
Incorrect injection tim-
ing
Individual injectors not
operating
Disconnect one delivery pipe at a time and listen
for changes in the engine sound.
WARNING!
!
Be careful when disconnecting the delivery
pipes as the pressure is extremely high and
could cause injury
Eect Cause Trouble shooting Action
Engine speed hunt-
ing at 4-5% speed
droop
The RSV governor
should not nowadays be
used for single-speed
operation (except on 9-
series engines)
- Change the injection
pump delivery valves
(1-hole or 2-hole) for
0-hole valves
Engine speed hunt-
ing at idling
Governor incorrectly
adjusted
- Tighten the idling
spring and adjust
engine speed
Below 700 r/min the
standard starter spring,
282 544 (Bosch 1 424
650 006) is too strong
- Fit a weaker starter
spring, part number
268 866
(Bosch 1 424 650 056)