Hyundai Solaris (Accent) 1.6 16V G4FC (2013): Cylinder Boring for Oversize Pistons

Part numbers are from the manufacturer's original catalogue. Check them against your VIN before ordering.

• Socket and wrench set
• torque wrench
• belt and pulley puller
• dial bore gauge 50-100 mm
• micrometer 75-100 mm
• feeler gauge
• piston ring compressor
• piston ring expander
• parts washer and compressed air. Boring and honing are done on machines at an engine machine shop

1. Determine whether boring is needed. Measure compression and check oil consumption. If the cylinders have scoring, or out-of-roundness or taper beyond the tolerance, a rebuild is needed. Minor scratches can be removed by honing without changing the size.
2. Remove the engine from the vehicle. Drain the oil and coolant, then disconnect the wiring harnesses, hoses, exhaust and drive components. Remove the cylinder head, oil pan and oil pump. Turn the engine over on an engine stand or a clean workbench.
3. Mark the connecting rod caps and pistons in cylinder order. Remove the connecting rod bolts and push the pistons out upward. Remove the crankshaft only if the journals need grinding or the main bearing shells need replacing. In that case, record the position of the caps and bearing shells.
4. Wash the block thoroughly. Remove the oil gallery plugs so the passages can be flushed of metal chips after boring.
5. Measure the cylinders with a bore gauge in two planes (along and across the crankshaft axis) at three levels: top, middle and bottom. The nominal cylinder diameter is 77.0 mm. Compare out-of-roundness and taper with the manufacturer's tolerance. Check the flatness of the block's cylinder head mating surface.
6. Choose the oversize step based on the most worn cylinder. If wear or scoring does not clean up at +0.25 mm, use +0.50 mm. Larger steps are not recommended on this block without installing new liners, because the wall is thin. If the wall does not allow boring, have the block sleeved with new liners.
7. Buy the piston and ring set and bring it to the machine shop along with the block. The machinist will bore each cylinder to the actual diameter of the pistons you bought, measured with a micrometer on the piston skirt. Cylinder diameter = piston diameter + clearance per specification. A rough guide for clearance is 0.02-0.05 mm; take the exact value from the manufacturer's specification or the piston manufacturer's recommendation.
8. Boring is done leaving an allowance of 0.03-0.05 mm for final honing. Honing is done with a plateau cross-hatch pattern with a cross-hatch angle of 45-60 degrees. Boring should be done with a torque plate that simulates the cylinder head installed and tightened, otherwise the cylinder geometry will distort after the head is tightened. Confirm that the shop does this.
9. After boring, wash the block with hot water, detergent and a brush, then blow out the passages and oil the cylinders. Wipe the cylinders with an oil-soaked rag until no dark residue is left on it. Only then install the parts.
10. Check the piston clearances. Check the ring end gaps by inserting each ring into the cylinder to a depth of about 20 mm (per specification). Position the ring gaps at about 120 degrees from each other, not on the piston pin axis.
11. Lubricate the pistons, rings and cylinders with engine oil. Install the pistons into the cylinders with a ring compressor, with the arrow or mark on the piston crown facing the timing belt side. Check the connecting rod orientation by the marks. Check the bearing clearances with Plastigage.
12. Tighten the connecting rod bolts in several stages per the manufacturer's specification (torque and angle are given in the specification; this engine uses torque-to-yield angle bolts). Check that the crankshaft turns freely after each connecting rod is installed.
13. Install the oil pump, the oil pan with a new gasket or sealant, and the cylinder head with a new gasket and new bolts. Tighten the cylinder head bolts strictly in the sequence from the center outward, in several stages (torque and angle per the manufacturer's specification). Set the timing marks, then replace the timing belt or chain, the tensioner and idler pulleys, and the seals.
14. Install the engine, then fill with fresh oil and coolant. Crank the engine with the starter without starting it until oil pressure builds (the warning light goes out). Start the engine and let it idle without load.
15. Break-in: for the first 1000-1500 km, avoid hard acceleration and high rpm, keep below 3000-3500 rpm, and avoid long periods at a constant speed and towing. Change the oil and filter after 1000-1500 km (after break-in).

• Boring is a precision machine operation: the cylinders are bored to the actual dimensions of your pistons, not to the "nominal" printed on the box
• Do not replace pistons and bore the block without taking measurements
• If the liner walls on this engine are already thin or have cracks, boring will not help; you need new liners or a replacement block
• This repair requires experience and careful assembly
• If you lack experience, leave the engine disassembly and assembly to a professional