Wärtsilä Vasa 12V32  //  Fuel Injection Pump Plunger Pairs PEO-G057SV-W

Restoring Sealing Integrity of Fuel Injection Pump Plunger Pairs PEO-G057SV-W (Wärtsilä Vasa 12V32 Engine)

Technical case study analyzing the loss of pressure retention and cyclic delivery in the high-pressure fuel injection pumps of a Wärtsilä Vasa 12V32 engine due to cat fines abrasion. Under load, specific fuel oil consumption (SFOC) had increased by 5.2 g/kWh.

FAILURE MODE Local hydro-abrasive wear and micro-erosion in the plunger spill ports area due to the impact of fine catalytic dust fractions (cat fines) in the HFO circuit.
DOWNTIME 3 days
COST ESTIMATE ~€6,500 including precision barrel honing, manufacturing of oversize plungers, and dynamic calibration testing.
ROOT CAUSE An increase in the radial working clearance between the plunger and the barrel up to 24 μm (nominal clearance is 6–8 μm), causing heavy internal back-leakage at the start of the delivery stroke.

Object Passport (As-Built)

Medium-speed four-stroke diesel engine Wärtsilä Vasa 12V32 operating on heavy fuel oil (HFO 380 cSt). High-pressure fuel injection pump (HPFP) Bosch-type, modification PEO-G057SV-W. Plunger and Barrel Assembly, OEM Part No. 165001. Running hours at the moment of inspection: ~14,200 hrs. A drop in exhaust gas temperatures on the A-side cylinder bank and a decrease in injection pressure were recorded.

Wear Mechanism & Defect Detection Results

Testing of fuel pump elements P/N 165001 on the test bench showed a critical drop in pressure retention time (the timing dropped to 9 seconds, compared to a norm of at least 30 seconds for this precision pair). This was caused by local hydro-abrasive wear in the plunger spill ports area due to the impact of fine catalytic dust fractions in the HFO circuit, which pushed the clearance to a critical 24 μm.

Engineering Intervention (Repair Protocol)

Due to high cost and long OEM lead times, a method of reverse engineering and precision geometry restoration was applied. The inner diameter of the barrel was machined on a specialized honing machine until ellipticity and taper were completely eliminated (cylindricity restored within ≤ 1.5 μm). A new oversize plunger was manufactured from high-alloy tool steel, surface treated for wear resistance, and precision lapped to obtain a stable running clearance of exactly 7 μm.

Prevention

The restored assembly remained within operational tolerances during post-repair monitoring and demonstrated stable injection characteristics under HFO operating conditions.

← Back