Diesel Engine Troubleshooting

Archive for the ‘Bosch Fuel Systems’ Category

Bosch RSV Governor Components

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Prior to describing the operation of the RSV governor, refer to Figure above which illustrates the major component parts and the associated linkage used with this governor model. Note that within the governor housing there are four springs used with this governor assembly:

• A starting aid spring
• The governor main spring
• An idle spring, sometimes referred to as a bumper spring
• A torque control spring

Written by Ed

September 6th, 2011 at 2:09 am

Bosch RSV Governor Diagram

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The RSVgovernor assembly is designed as an all-range (variable) governor which functions to control the engine idle and maximum speeds, in addition to allowing the operator to place the throttle at any position between idle and maximum where the governor will control the speed setting minus the droop The RSV governor is widely used on combination on- and off-high way truck applications, as well as farm tractors and industrial and marine units employing the M, A, MW,or P Bosch model inline multiple-plunger injection pumps. Although similar in external appearance to the RS limiting-speed (minimum/maximum) governor described in this section, the RSV does allow several adjustments at points outside the housing that are not available on the RS unit. Figure above illustrates an external view of the RSV governor housing with the various external adjustments shown. These include:

• The idle-speed screw
• The auxiliary idle-speed spring or bumper screw
• The throttle lever linkage maximum speed adjusting screw

Written by Ed

September 6th, 2011 at 2:07 am

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Bosch Governors

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Robert Bosch governors used with inline pumps (M, A, MW, and P) can look the same externally; however, they
are designed for different types of engine applications, and therefore engine speed control can be governed at different settings of the throttle. Types of governors manufactured by Robert Bosch Corporation and used on their inline injection pumps in truck applications are described below.

The letter designations used for these mechanical governors take the following forms:

R: flyweight governor
S: swivel lever action
Y: variable-speed (all-range) governor
Q: fulcrum lever action
K: torque earn control
W: leaf spring action

For example, if the nameplate on a governor read EP/RS275/1400AOB478DL, this would mean:

EP: found on older governors, no longer used
RS: R/flyweight governor with swivel lever action, minimum/maximum (limiting speed) type of governor
275: low-idle pump speed (this would be 550 rpm engine speed, four cycle)
/: also indicates mini max (limiting speed) governor
1400: full-Ioad-rated speed (this would be 2800 rpm engine speed, four cycle)
A: fits on A-size inline injection pump
0: amount of speed regulation (droop percentage)
B: execution-not used to indicate the original design on governors; A, first change;B, second change; and so on
478DL: application and engineering information only

Written by Ed

September 6th, 2011 at 2:02 am

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Bosch Secondary Fuel Filter Pressure Test Diagram

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Pressure tester gauge connected between the secondary fuel filters and the injection pump inlet: 1, fuel filter housing; 2, transfer pump; 3, tester.

Refer to Figure above and disconnect the fuel line between the outlet side of the secondary fuel filter(s) and the inlet side of the fuel injection pump. Insert a special pressure gauge or, alternatively, a fuel pressure gauge and clear plastic line between the filters and injection pump as shown in Figure above.

Written by Ed

September 5th, 2011 at 4:50 am

Bosch Vacuum Pump Restriction Test Diagram

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Vacuum tester connected between the fuel transfer pump inletside and the primary filter/fuel-water separator 1. fuel filter housing; 2, transfer pump; 3, tester

This test allows the mechanic/technician to determine if there is a high restriction to fuel flow to the suction side of the fuel transfer pump. If there is, the injection pump will not receive enough fuel. This will be accompanied
by lack of power as well as possible rough idling and stalling. Either a vacuum gauge or a mercury manometer can be use to check the restriction to fuel flow. However if a mercury manometer is teed in to the fuel system in place of the special gauge make sure that you hold or mount the manometer higher than the engine. Failure to do this can result in diesel fuel running back in to the manometer when the engine is stop. A low reading is what we are looking here , since this indicates that the fuel lines and connections are offering a minimum restriction to flow at the suction side of the fuel transfer pump.

Written by Ed

September 5th, 2011 at 4:41 am

Bosch Relief Valve and Pump Pressure Test Diagram

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Fuel pressure gauge connected between the transfer pump outlet and secondary fuel filters: 1, fuel filter housing; 2, transfer pump; 3, tester

This test is a check to ensure that the injection pump relief valve is, in fact, opening at the correct pressure and that the transfer pump is performing correctly. If the relief valve is stuck open or is opening at too low pressure, the fuel delivery pressure within the injection pump housing will be too low to sustain sufficient flow to the plunger and barrel of the individual pumping assemblies. On the other hand, if the relief valve is stuck closed or opens at too high a pressure setting, the fuel within the injection pump housing, which is also used for cooling and lubricating purposes, will run hot. This can result in a loss of horse power due the expansion of the fuel, since a less dense fuel charge will be delivered to the injectors and combustion chamber. In addition fuel that is too hot can cause internal pump pluger damage due to its instability to properly cool and lubricate the component parts. Note that only 25 to 30% of the fuel delivered to the injection pump housing is actually used for combustion purposes. The remainder cools and lubricates the injection pump components.

Written by Ed

September 5th, 2011 at 4:31 am

Bosch Automatic Timing Device

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In the combustion process, diesel fuel takes a certain amount of time to ignite and burn. As the engine runs faster, the burn time remains the same, and much of the burning takes place after TDC (top dead center). This is called ignition lag and almost always results in lowered performance. To offset this ignition lag, fuel must be injected sometime before TDC to give good performance at rated speed. However, with this fixed advance of injection, engine performance is optimum at rated speed only. Engines that vary speeds over a wide range, that is, automotive vehicles, need injection timed correctly at all speeds. This is the function of the timing device.

The Bosch automatic timing device is used on inline camshaft driven pumps (Figure 19-46), and is classified
as a flyweight-operated device. Mounted at the front of the injection pump on the camshaft, the timing device is connected to the driving gear of the engine (Figure 19-46). Through the action of centrifugal force, the flyweights swing outward with increasing speed. Rollers mounted on the flyweights push against the cam plate (Figure 19-47), which is connected to the pump camshaft. This causes the camshaft to rotate a maximum of 8°, providing proper timing in relation to engine speed.

Automatic Timing Advance Unit 300x133 Bosch Automatic Timing Device

Stop pins limit the maximum amount of advance that can be obtained from any timing advance assembly. As with any automatic timing device, should the unit become worn or damage, fuel injection timing will not be con trolled correctly. Result in poor engine performance and possible engine damage. Generally, if the timing advance unit were to stick in the full-advance position, the start of fuel injection would be too early at an idle speed, and severe combustion knock would result, together with a tendency for white smoke to appear at the exhaust stack. On the other hand, a timing advance unit that will not advance past the idle setting would result in late injection and the engine would be very sluggish, together with black smoke appearing at the exhaust stack though incomplete combustion.

Automatic Timing Advance 234x300 Bosch Automatic Timing Device

Written by Ed

September 3rd, 2011 at 10:18 am

PF Rack Setting

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Engines equipped with individual PF pumps usually have their fuel racks (control rods) interconnected by adjustable mechanical linkage to permit balancing the fuel flow to each nozzle and the combustion chamber.

Some larger engines employ a micrometer-type knurled knob adjusting screw that the technician can rotate manually to obtain very fine adjustment of fuel delivery. On large, slow-speed engines, fuel delivery and cylinder balance are best achieved by monitoring the individual cylinder exhaust temperatures by looking at the pyrometer gauge(s) and adjusting the individual fuel rack adjustment knobs.

Written by Ed

September 3rd, 2011 at 8:54 am

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Bosch Injection Pump Adjusting Idle Speed

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The idle adjustment screw location will vary based on the type of governor being used.

Once the engine is started, adjust the idle speed on industrial engines using an RSV governor by loosening the locknut and turning the screw (I), shown in Figure 19-43. CW rotation will increase the idle speed, and CCW rotation will decrease the idle speed. On automotive engines equipped with an RQV governor, refer to Figure 19-44 and using a 10-mm wrench and screw driver, rotate the screw CCW to raise the engine speed and CW to decrease the idle speed.

1. Start and run the engine at its idle speed. Use a tach and note the idle rpm. Compare this with the spec stamped on the engine CPL plate.

2. If idle adjustment is required, loosen the lock nut and back out the bumper spring screw until there is no change in the idle speed.

3. Adjust the idle screw to obtain an idle speed approximately 20 to 30 rpm lower than that recommended and lock the retaining nut.

4. Slowly turn the bumper spring screw (2) shown in Figure 19-43 CW only enough to bring the desired idle rpm to a stable speed, then lock the retaining nut.

Bosch RSV governor Bosch Injection Pump Adjusting Idle Speed

Bosch RSV governor screw location Bosch Injection Pump Adjusting Idle Speed

Written by Ed

September 3rd, 2011 at 8:47 am

Bosch Engine to Pump Timing Marks

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(a) Example of engine-to-pump timing marks which can be referenced when spill timing the injection pump to the No. I cylinder (some engines use No.6 cylinder) (b) Example of the actual timing reference marks between the injection pump to engine drive coupling

Written by Ed

September 3rd, 2011 at 6:31 am

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