BOSCH VE 250 INJECTION PUMP

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Lynne Thomasine Hodges
5 years ago
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1 1.0 BOSCH VE 250 DIESEL INJECTION PUMP Land Rover fit the Bosch VE-type rotary distributor diesel injection pump onto their 300 TDI engines. Two main variants were installed: the standard models were fit with the R509 while engines provided with Exhaust Gas Recirculation systems were fit with the R509/1. Both of these models had boost control LDA or aneroid modules (the bulbous housing on the top of the pump in the photo below), two-speed govenors with auto-advance, and electrical fuel shut-off solenoids, while the EGR-equiped units included a throttle position sensor. Photo courtesy of As noted above, the R509 pumps are distributor-type, using a single plunger-and-barrel assembly to distribute fuel. Fuel is delivered to the cylinders via high-pressure valves (one for each cylinder) set into the distributor head of the pump (the dark grey object at the bottom-left hand of the unit above); each valve is connected to its respective injector via a thin steel pipe that is screwed onto the high-pressure valve end where it protrudes from the distributor body. It is fundamentally important to ensure that the three main engine components of the fuel delivery and combustion systems are correctly set relative to one another, as failure to ensure this will result in the engine running poorly (if at all), providing poor power output as a result of improper fuel combustion, and/or possibly overheating catastrophically resulting in damage to combustion chamber components. These three main engine components are: a. The crankshaft, which provides the piston travel geometry that affects both the induction of air and compression of the fuel/air mixture, the final discharging of exhaust gases, and which transfers the resulting power stroke to the drive train as a consequence of the combustion of the injected diesel/air mixture; b. The camshaft, which provides the geometry for the opening and closing of the inlet and exhaust valves; and c. The injection pump, which injects the appropriate amounts of diesel to each of the four cylinders via dedicated two-stage injectors at the correct times and in the correct sequence. The injection pump timing profile is constantly adjusted in response to engine RPMs via a mechanical governor or electronic control unit, and by boost pressures provided by the exhaust gas turbocharger (via the LDA or aneroid unit). Jode N. Anderson

2.0 TIMING MARKS IN THE TIMING CASE The 300 TDI firing sequence is statically timed by ensuring each of the above three components is correctly set: a. Crankshaft the no.

2 2.0 TIMING MARKS IN THE TIMING CASE The 300 TDI firing sequence is statically timed by ensuring each of the above three components is correctly set: a. Crankshaft the no. 1 cylinder is placed at Top Dead Centre (TDC). This is done by aligning a mark (arrow) that is cast into the rear timing cover with the keyway of the crankshaft timing belt drive gear when at 12 o clock (see right-most red arrow in the image below). At this position, a timing pin can be inserted into the bottom of the flywheel housing and gently pushed into a notch on the flywheel. Diagram courtesy of forum.difflock.com b. Camshaft the camshaft, which pushes the pushrods up and controls their downward movement in a particular profile via cams cast integral to its shaft, is set to suit the no. 1 piston being at TDC. This is done by aligning an arrow that is cast into the rear timing cover with a mark cut into the camshaft drive gear (see pair of red arrows pointing to each other in the image above). c. Injection pump the injection pump is set to deliver fuel to cylinder no. 1 advanced somewhat of TDC (in the case of the non-egr 300 TDI engine, this advance is measured as 1.54 mm of lift of the injection cam plate see below). This should occur when a keyway in the injection pump drive gear hub aligns with a hole in the injection pump housing, and a 9.5mm rod can be pushed through the drive hub into the housing (see red line at the left in the above image). Both the camshaft and the injection pump turn one full revolution after TWO full revolutions of the crankshaft, in order to allow for the four strokes required of each piston. 3.0 SETTING THE INJECTION PUMP LIFT (ADVANCE) In order for the engine to run, fuel must be delivered in the correct amounts at the correction points of the pistons travel. The correct piston and cam relationships are set as noted above by the use of timing marks within the timing case. The injection pump, unlike the crank- and camshafts, consists of numerous moving parts within its assembly, all of which must work as one unit. Testing the performance of those components is beyond the scope of this article, and doing so requires testing machines costing several thousands of dollars tools that are typically beyond the reach of DIY mechanics. Jode N. Anderson

However the DIY mechanic who has removed a functioning pump from his or her Landie can easily refit it back onto the engine in a manner that ensures proper fuel delivery and combustion.

3 However the DIY mechanic who has removed a functioning pump from his or her Landie can easily refit it back onto the engine in a manner that ensures proper fuel delivery and combustion. Doing so requires that the no. 1 cylinder is at TDC, the camshaft timing marks are correctly aligned as noted above, and the pump itself is advanced by a specific lift as mentioned above. Anyone who has removed a VE pump from their engine and tried to turn its drive shaft knows that doing so requires some effort. This is because the pump drive shaft has a spring-loaded cam plate fixed to it, which in the case of the 300 TDI has four lobes each at 90 degrees to the next which drive the injection of fuel to the four cylinders. This plate is spring-loaded to ensure that the fueling cycle moves smoothly throughout its action. LOBED CAM ON PUMP DRIVESHAFT Photo courtesy of Robert Bosch GMBH If the injection pump or pump drive gear has been removed from the engine, the pump drive shaft will need to be re-positioned in order to provide the correct advance. This advance can be set statically by rotating the drive shaft a specific number of degrees, but is typically done by using a dial indicator to measure the distance that the cam and its shaft lift away from their resting position (where no fuel delivery takes place). The Bosch workshop manual states that this lift should be between 1.52 mm and 1.56 mm for a non-egr vehicle, whereas the Land Rover workshop manual gives this figure as 1.54 mm bang in the middle of the Bosch values. Setting pump advance with the pump taken off the engine is a fairly straight-forward procedure that nonetheless requires care. You will need the following tools: a. A dial indicator (I use a metric indicator, which means I don t have to work out the imperial values for the metric measures given in the workshop manual); b. A long probe to temporarily replace the nib on the point of your dial indicator; c. A bracket for fixing the dial indicator onto the rear of the injection pump; d. An M8 threaded adaptor for mounting the dial indicator bracket to the pump; Jode N. Anderson

A helpful local injection pump specialist kindly gave me a locking plug: The timing advance is set as follows: 1. Align the injection pump with TDC for no.

4 e. A metal plug for locking the injection pump shaft once it has been advanced. I bought a set of two probes, a bracket plus four threaded adaptors via a popular auction site on the internet (cost around $25). The photo below shows a typical set of the above tools. A helpful local injection pump specialist kindly gave me a locking plug: The timing advance is set as follows: 1. Align the injection pump with TDC for no. 1 cylinder the high-pressure fuel valves mentioned above are designated A, B, C and D, and are arranged to follow the clockwise rotation of the pump and engine when viewed from the front of the vehicle as one faces the rear. If you follow the injector pipes, you will find that the supply to no. 1 cylinder is connected to high-pressure valve C (the valves are marked on the distributor head, see image below). Jode N. Anderson

The Bosch pump is designed such that the pump drive gear keyway (at the timing housing end of the driveshaft) aligns with the delivery valve that is injecting fuel at that moment.

The keyway won t line up exactly because of the spring loading of the driveshaft, but it will be point toward valve C, which is when no. 1 cylinder is about to begin its combustion cycle. 2.

5 The Bosch pump is designed such that the pump drive gear keyway (at the timing housing end of the driveshaft) aligns with the delivery valve that is injecting fuel at that moment. We therefore want to turn the pump driveshaft clockwise (seen from the front) until the keyway is generally aligned to valve C (no. 1 cylinder). The keyway won t line up exactly because of the spring loading of the driveshaft, but it will be point toward valve C, which is when no. 1 cylinder is about to begin its combustion cycle. 2. Attach the dial indicator to the pump clamp the pump in a bench vice, remove the bolt at the rear of the pump (in the centre of the distributor head), insert the long probe that you have attached in place of the nib of your dial indicator and mount the dial indicator where the threaded plug was. Zero the gauge. Jode N. Anderson

3. Fix the locking plug to the pump using an Allen wrench, remove the stud on the side of the pump near the front (see picture below), insert the locking plug behind the stud and lightly screw the

6 3. Fix the locking plug to the pump using an Allen wrench, remove the stud on the side of the pump near the front (see picture below), insert the locking plug behind the stud and lightly screw the stud back into the pump body. Don t tighten the stud yet. 4. Set the lift and lock the pump - now turn the driveshaft clockwise (again, when viewed from the front of the pump) until the dial indicator moves to 1.54 mm; hold the driveshaft steady at that position and tighten the stud/locking plug to prevent the pump shaft from rotating back off the cam plate springs. Remove the dial indicator and replace the bolt, using a new ring gasket to prevent leaks. 5. Refit the pump to the vehicle now install the pump back onto the vehicle, following the steps in the workshop manual. Pay particular attention to the sequencing regarding the torquing of the studs to the timing cover and the bolts to the mounting bracket, as this procedure was revised by LR to help address the timing belt alignment fault in the first 300 TDI engines: torque the studs to the timing cover, finger-tighten the pump-bracket and bracket-block bolts, torque the pump-to-bracket bolts and finally the bracket-to-block bolts. 6. Refit the injection pump drive gear now install the drive gear to the injection pump driveshaft: fit the gear and washer/nut loosely to the driveshaft, align the gear to the injection pump using the 9.5mm timing pin, and torque the nut in place. You obviously don t want to break or bind the timing pin, so try to hold the driveshaft with molly grips or similar whilst torquing the nut. 7. Remove the locking plug from the injection pump you can now remove the stud and locking plug from the side of the injection pump, which now that the pump is back on the vehicle is a bit tricky to get to. Refit the stud to the pump with a new O-ring, and tighten securely to prevent leaks. You can now fit the timing belt and set the timing as described in the workshop manual. Jode N. Anderson

The Four Stroke Cycle

The Four Stroke Cycle 1 Induction As the piston travels down the cylinder it draws filtered air at atmospheric pressure and ambient temperature through an air filter and inlet valves into the cylinder. 2 Compression When the