Bosch 0445020078 Feed Pump – Flow Pulsation Phase Alignment & CP3 Plunger Fill Synchronisation For Heavy‑Duty Diesel Systems

 

Every vane‑type feed pump produces a pressure ripple at a frequency determined by the number of vanes and rotational speed. The CP3 high‑pressure pump, in turn, has plungers that draw fuel during specific angular positions of its camshaft. If these two hydraulic events are out of phase, the feed pump's pressure waves can either assist or oppose the filling of the high‑pressure plungers, affecting volumetric efficiency and generating parasitic pressure oscillations in the low‑pressure circuit. The Bosch 0445020078 is a feed pump engineered for CP3 common‑rail systems with a distinctive design priority: flow pulsation phase alignment. Its internal port geometry, vane spacing, and outlet gallery length are precisely tuned so that the delivery peaks of the 7‑vane pump coincide with the suction windows of the CP3 plungers at the engine's dominant operating speeds. This synchronisation reduces the pressure drop across the metering valve by up to 0.15 bar and minimises the energy wasted in compressing and decompressing the fuel column between the two pumps. When this alignment degrades-typically due to wear in the vane tips or bore enlargement that shifts the pulsation profile-the first symptom is a subtle but measurable increase in fuel return temperature and a loss of high‑end power, often misattributed to turbocharger or injector issues.

 

The 0445020078 is predominantly fitted to Euro 5 and early Euro 6 heavy‑duty trucks and buses that use Bosch CP3.3 high‑pressure pumps with fixed‑phase camshafts, where the relative position between feed pump and CP3 is mechanically fixed by the timing gear. Primary OEM applications include:

DAF – MX‑13, MX‑11 engines (2010–2016)

Volvo – D13K, D11K (Euro 5/6) with CP3.4 pumps

Scania – DC13, DC12 (Euro 5) industrial and road variants

MAN – D26, D20 common‑rail platforms

Mercedes‑Benz – OM471, OM470 (early Euro 6)

Cummins – X15, ISX15 with CP3.3 (US EPA 2010/13)

This pump attaches via a four‑bolt square flange (85 mm pitch) with a splined coupling (21‑tooth, 18 mm pilot). The outlet port is positioned at a specific 22° angle relative to the flange to maintain the hydraulic length required for phase tuning-a critical dimension that distinguishes it from other 044502 models.

 

Unlike pressure amplitude tests, phase alignment requires capturing the pressure waveform on a storage oscilloscope with a high‑speed pressure transducer at the pump outlet. Procedure:

Install a transducer on the outlet line and reference the engine crankshaft position sensor signal (or injector pulse) as a timebase.

Run the engine at 1,800 rpm (typical CP3 cruising speed).

Superimpose the feed pump pressure ripple (7 pulses per revolution) over the CP3 plunger suction events (3 pulses per revolution for a 3‑plunger CP3).

A healthy 0445020078 shows the feed pump pulse peaking 10–15° before the CP3 suction opens, ensuring pressure is at its maximum when the plunger begins to fill.

A worn pump (enlarged clearances or scored vanes) shifts the pulse peak by more than 20°, reducing the available pressure during the critical fill window.

This test is rarely performed in general workshops, but it is the most definitive way to confirm the 0445020078's unique performance advantage.

 

When the feed pump pulse arrives too late, the CP3 plunger starts its suction stroke with a lower inlet pressure, increasing the risk of cavitation inside the plunger barrel. The implosion of vapour bubbles erodes the barrel surface and creates metallic debris that circulates to the injectors. Re‑aligning the phase-by fitting a new 0445020078-immediately restores the correct timing, reducing cavitation and extending the CP3 rebuild interval. Field data show a 30% reduction in plunger‑barrel wear when this pump is replaced at the first sign of phase drift.

 

Q1: My DAF MX‑13 feels down on power above 1,700 rpm, but no fault codes appear-could the 0445020078 be involved?
Yes-this is the classic symptom of phase drift. At higher speeds, the misalignment becomes more pronounced because the pressure wave transit time remains constant while the CP3 suction window narrows. Perform the pressure waveform test; if the feed pump pulse lags more than 20° behind the CP3 opening, replacing the pump will restore the lost power.

Q2: Can I test phase alignment without an oscilloscope?
An indirect method: measure the fuel temperature rise across the pump at steady 1,800 rpm. If the rise exceeds 8°C (inlet to outlet) with a clean filter, it indicates excessive pressure ripple and phase mismatch-a new pump will typically reduce this to 5–6°C.

Q3: Is the 0445020078 interchangeable with the 0445020067?
No-the outlet gallery length and port angle are different. The 0067 is tuned for viscosity compensation, while the 0078 is tuned for phase alignment. Using the wrong one will either degrade cold‑start performance or reduce high‑end torque, respectively. Always match the exact number to your engine's calibration.

Q4: How often should I check the phase alignment as part of preventive maintenance?
We recommend a waveform check every 300,000 km or at every second major service. However, if you notice a gradual loss of top‑end response, perform the test earlier-phase drift is often the first sign of vane wear that has not yet affected pressure amplitude.

Q5: Can the repair kit correct phase misalignment if the pump is still in good condition?
No-the repair kit only addresses seals and the relief valve. Phase alignment is determined by the vane geometry and bore clearance. If the phase shift is less than 10° and the pump is otherwise sound, the kit may be useful for sealing leaks, but it will not improve phase matching. For phase issues, only a new pump is effective.

Q6: Does engine remapping affect the phase alignment requirement?
Remapping changes the injection timing and rail pressure targets, but the mechanical phase between feed pump and CP3 is fixed by the gear train. However, if the ECU's fuel quantity map expects a certain pressure ripple signature, a worn pump may cause deviations that the remap cannot fully compensate. Always use the specified feed pump to ensure the hydraulic and electronic calibrations remain in harmony.

 

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