SERVICE MANUAL
ROBERT BOSCH MODEL MW INJECTION PUMP
Section 11
TIGHTENING UNSEALED NUTS OR SCREWS TO
CORRECT LEAKAGE
Unsealed nuts or screws may be tightened to stop fuel or
lubricating oil leakage. When careful tightening does not
stop leakage, fittings which use copper gaskets can be
removed. For example, injection pump housing fuel inlet
and outlet fittings and oil inlet fitting use copper gaskets
between fitting and housing which can be replaced.
IF DELIVERY VALVE HOLDER (FIGURE 27) LEAKS,
DO
NOT
TIGHTEN
HOLDER.
FOLLOW
PROCEDURES IN CURRENT WARRANTY MANUAL
TO RESOLVE HOLDER LEAKAGE.
Figure 27.
REPAIRING
OR
REPLACING
FUEL
INLET
OR
RETURN FITTINGS
Replacing Fuel Return Check Valve The fuel return
check valve (Figure 28) has a nominal opening pressure
of 18 psi and retains fuel within injection pump when
engine is stopped. Return fuel flow from pump is
controlled by an orifice in the fuel return hose.
The valve can be cleaned or replaced as required. To
remove valve, disconnect fuel return hose at fuel return
line fitting located just below intake manifold center.
Noting position of valve will aid in its reinstallation.
Figure 28.
Injection Pump Housing Pump Return Connector
and Elbow
Fuel leakage can occur at injection pump housing return
elbow or connector (Figure 28). If tightening does not
stop leakage, install new elbow fitting or use Loctite
Hydraulic sealant on elbow. Install a new copper gasket
if fuel leaks at pump housing connector.
Injection Pump Housing Inlet Connector and Elbow
The final filter to pump housing hose (Figure 29) uses a
flex connector at the filter header. Remove hose at
header, then hose bracket at bottom of pump housing
prior to removing hose. The hose connects to a brass
elbow which is threaded into the pump housing
connector (Figure 29). Fuel leaks may be corrected by
installing a new copper gasket between pump housing
and inlet connector or by installing a new elbow.
CGES-185-3
PRINTED IN UNITED STATES OF AMERICA
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