Is fixing a cylinder expensive?

The cost of repairing a cylinder can indeed be a significant expense, but whether it's "expensive" or not mainly depends on the extent of the damage and how you plan to repair it. It's like repairing a house; painting the walls and repairing the foundation are completely different in terms of cost.

Here are some of the main factors affecting repair costs:

1. Severity of the damage

Minor scratches (honing): If the inside of the cylinder only has minor wear or slight rust due to prolonged storage, simple honing is sufficient. This type of repair is usually relatively inexpensive, mainly involving labor and simple equipment costs.
Deep scoring (cylinder boring): If the piston has left deep grooves due to high temperature or lack of lubrication, the entire cylinder wall needs to be machined down and then polished. This involves not only complex machining, but you also need to buy a set of "oversized" pistons and piston rings to match, naturally doubling the cost.

2. Engine type

Single motorcycle cylinder: This type of repair is relatively inexpensive. Because there is only one part, disassembly and assembly are easy, and the machinist can work quickly. Parts for many small-displacement commuter vehicles are readily available, and replacing the entire cylinder block might even be cheaper than repairing the old one.
Multi-cylinder engine (such as four-cylinder or six-cylinder): Once multiple cylinders are involved, the cost increases exponentially. Even if only one cylinder is damaged, to ensure balanced engine operation, the other cylinders usually need to be inspected or repaired as well, resulting in incredibly high labor and parts costs.

3. Special materials and technology

Special coatings: Many high-performance cars now have a shiny, hard metal coating on the inner wall of the cylinder for wear resistance. If this type of cylinder is damaged, ordinary repair shops cannot repair it; it either needs to be sent back to the original factory for re-plating and honing, or the entire unit must be scrapped and replaced. This type of repair cost can be shockingly high.
Integrated cylinder block: In some modern engines, the cylinders are cast together with the entire engine block. If one cylinder is damaged, it may mean replacing the entire large cylinder block, which is essentially like giving the car a new "heart."

4. Hidden Costs: Disassembly and Reassembly

"Open-heart surgery": To remove and repair the cylinder, the entire upper part of the engine must be disassembled. The gaskets, various bolts, coolant, and engine oil involved in this disassembly and reassembly process all cost money.
Related replacements: Repairing a cylinder is never just about repairing the cylinder itself. You usually need to replace the pistons, piston rings, and connecting rod bearings, and even clean the valves and carbon deposits. These parts together often cost much more than the machining costs alone.