HYDRAMECHANICAL PROTECTIVE SYSTEM
TROUBLESHOOTING
7. ENGINE WILL NOT SHUTDOWN WHEN CHECKING LOW ENGINE OIL PRESSURE
PROTECTION CIRCUIT
Cause
Correction
Remove the actuator. Check surface finish of bore and polish, if necessary.
Fuel Shutoff Actuator Stuck In The
Run Position Remove
Put a small amount of clean oil in the bore and on the seal. Move the rod and
piston in the actuator cylinder to check for free movement. Replace actuator, if
necessary.
Orifice Plugged In Diverter Valve
Disconnect oil return line (3) at the diverter valve. Crank the engine without
using the start-up over-ride valve. Oil should flow from the diverter valve outlet
port.
Orifice Not Installed In Control
Remove control group from engine and disassemble. Install or replace orifice
Group
if needed.
Oil Flow To Drain Is Not Enough
Install a manual operated ball or gate valve in the engine oil pressure sensing
To Create A Fault Condition
line. Slowly close the valve to add more restriction to flow. If engine shutdown
does not occur, the shutoff control group needs repair.
8. SHUTOFF CONTROL UNIT DOES NOT OPERATE
Cause
Correction
Drive Coupling Failure
Start the engine and run supply line at low idle. Loosen the nut that holds oil
supply line (4) at the shutoff control group, see Figure 1. Oil under pressure
present should be present. If not, remove shutoff control group and inspect
the drive coupling. Make a replacement of parts as needed. A pressure gauge
installed in oil supply line (4) [see Figure 1] can also be used to make this
check. A minimum pressure of 590 kPa (85 psi) at high idle should be the
reading.
Not enough System Oil Pressure
Make sure there is oil in the reservoir for the system. Low oil pressure can be
caused by a faulty oil pump relief valve (18) or fuel shutoff sequence valve
(15), see Schematic No. I in the System Operation section for part locations.
Make a replacement or repair as needed.
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