First, Preparation and Pre-inspection
1. Condition Verification: Record ESN/CPL, measure cylinder pressure, oil pressure, smoke emission, and abnormal noises; verify compression ratio (typically 13.9:1/15.5:1) matches pistons and cylinder liners.
2. Repair Approach Selection:
In-frame: No cylinder block disassembly. Replace pistons, rings, main/connecting rod bearings, cylinder liners, and valve assemblies. Suitable for routine overhauls, offering low cost and short turnaround.
Out-of-frame: Complete engine disassembly. Repair/replace cylinder block, crankshaft, camshaft, etc. Suitable for severe wear/failures, restoring factory performance.
Tools and Materials: Torque wrench, bore gauge, dial indicator; OEM/certified overhaul kit (pistons, rings, cylinder liners, main/connecting rod bearings, thrust plates, upper/lower gaskets, oil seals); cleaning solvent, compressed air, sealant, threadlocker.
Second, Disassembly and Cleaning of rebuilding engine K19
1. External Removal: Detach accessories (alternator, starter motor, turbocharger, fuel/oil/coolant filters), drain fluids, protect openings and electrical interfaces.
2. Cylinder Head Removal: Sequentially loosen cylinder head bolts, inspect for deformation/cracks; remove valve assemblies, mark and measure valve clearances (intake 0.36mm, exhaust 0.81mm).
3. Cylinder Block Disassembly: Remove piston-connecting rod assemblies, crankshaft, camshaft; remove cylinder liners (wet-type), inspect sealing surfaces.
4. Cleaning and Blowing: Degrease and clean components; blow through oil passages/water jacket with compressed air; clean precision parts like nozzles and bearings separately to prevent damage.
Third, Critical Inspection and Repair Standards
1. Cylinder Block/Head: Cracks (magnetic particle/penetrant testing), flatness ≤0.05mm; milling/replacement required if exceeded. Water/oil passages must be unobstructed.
2. Crankshaft: Journal roundness/cylindricity ≤0.02mm, surface roughness Ra≤0.8μm; Dynamic balance testing; grind and chamfer for reinforcement if necessary; connecting rod big end bore deformation ≤0.02mm.
3. Cylinder Liners: Inner diameter tolerance ±0.02mm, roundness/cylindricity ≤0.03mm; replace if wear exceeds limits; wet-type liner press-fit clearance must meet OEM specifications.
4. Piston/Rings: Piston crown free of scorching/cracks; skirt clearance 0.15-0.25mm; piston ring end gap and side clearance meet OEM values; good elasticity with no fatigue.
5. Valves/Guides: Valve sealing face free of dents; uniform contact ring band; guide-to-valve stem clearance 0.05-0.10mm; replace if wear exceeds limits.
Fourth, Assembly and Torque Specifications
1. Cylinder Block Assembly: Install main bearings, cold-fit crankshaft, tighten per OEM sequence and torque (main bearing cap bolts approx. 340-380 N·m), check axial clearance (0.10-0.20 mm).
2. Piston Connecting Rod: Install piston rings correctly (distinguish between compression and oil rings). Cold-fit connecting rod bearings. Torque connecting rod bolts to approximately 220-250 N·m with reliable locking.
3. Cylinder liner installation: Apply sealant to wet-type liners, press-fit into position, ensuring flush alignment with cylinder block surface and no leakage.
4. Cylinder head installation: Clean sealing surfaces, replace gasket; tighten cylinder head bolts in a cross-pattern sequence in multiple stages (approx. 480-520 N·m), performed on a cold engine.
5. Valve Assembly: Replace valve seat inserts/guides and re-machine; grind valves to ensure proper sealing; adjust valve clearance (cold engine: intake 0.36mm, exhaust 0.81mm).
6. Fuel System: Calibrate PT fuel pump; pressure test injectors for proper atomization and no dripping; calibrate injection timing per CPL code.
