PDP-U804 Diesel Fuel Injection Plunger Barrel Assembly

PDP-U804 DIESEL FUEL INJECTION PLUNGER BARREL ASSEMBLY

The PDP-U804 Diesel Fuel Injection Plunger Barrel Assembly is a heavy duty, high precision fuel injection pumping element for large bore medium speed marine and industrial diesel engines. It is produced mainly for the S.E.M.T. Pielstick PC2.5 series of engines and developed to meet the severe requirements imposed on fuel systems by L’Orange GMBH. This crucial part is the high pressure heart of the injection pump.

The PDP-U804 includes a precisely matched 30mm diameter plunger and barrel bore that works at high cycle pressures. The assembly uses tiny clearances to avoid hydro-lock and blow-by when handling heavy fuel oil (HFO), marine diesel oil (MDO) and ultra-low sulfur marine gas oils. This generates a positive hydraulic seal that ensures precision metering, accurate injection timing and the best thermal stability for complete maritime load profiles.

Model Identification

• Manufacturer Part Number (MPN): PDP-U804
• NATO Stock Number (NSN): 2815-01-178-9460
• National Item Identification Number (NIIN): 011789460
• Primary OEM Manufacturer: L’Orange GMBH (CAGE Code: D9621)

Specifications: PDP-U804 Plunger

Technical Features

1. For Pielstick PC2.5 Engines : Precision-ground to match the displacement and stroke velocity curves of the S.E.M.T. Pielstick PC2.5 medium-speed power plants.
2. 30mm Micro-Lapped Plunger Diameter: Precise 30mm bore diameter with sub-micron radial clearances to withstand pressures in excess of 1,000 bar without hydraulic slip.
3. Ultra Hardened Alloy Construction: Constructed of superior tool steel alloys heat treated to a Rockwell Hardness scale to resist cavitation, high velocity fuel erosion and sulfur corrosion from heavy fuel oils.
4. Integrated Fuel Helix / Control Edges The precision-machined control helix delivers ultra-precise fuel spill and effective metering time throughout a wide range of speeds and loads.
5. Exact Fit Modular Replacement Full mechanical compatibility with original L’Orange pump housings maintaining exact alignment with fuel rack and governor link mechanisms.

Applications/Usage

• Marine Propulsion: Main propulsion engines on container ships, bulk carriers, roll-on/roll-off (RoRo) vessels, and naval auxiliary ships running Pielstick PC2.5 configurations.
• Marine Power Generation: Stationary auxiliary diesel generator sets responsible for critical shipboard electrical grids.
• Industrial Power Plants: Land-based peak-shaving diesel power plants and distributed energy stations utilizing heavy-duty medium-speed diesel engines.

Compatible Engine Models

• S.E.M.T. Pielstick: PC2.5, PC2.5V, PC2.5L (Including dual-fuel variations)
• Colt-Pielstick: PC2.5 Series built under license
• Fairbanks Morse: 2815 Series Heavy Diesel Engines

Engineer’s Guide:

• Never Intermix Plungers and Barrels: The PDP-U804 is an individually micro-lapped pairing. If you open multiple boxes during a critical top-end overhaul, ensure that the unique numbers etched on the plunger body remain strictly matched with their corresponding barrel barrel sleeve. Swapping plungers between different barrels can trigger immediate hydraulic seizure or excessive fuel leak-off due to micro-inch tolerance deviations.
• Pro Tip on Storage & Commissioning: These components are protected with highly viscous anti-corrosion storage oils. Prior to installation into the injection pump body, do not scrape or use harsh mechanical brushes. Instead, immerse the unit in clean, filtered marine gas oil (MGO) or calibrating fluid. Work the plunger manually through its complete stroke within the barrel until the preservation oil dissolves entirely and the movement is completely smooth. Check the fuel rack timing marks immediately upon seating to verify absolute geometric calibration.