Should the engine block be repaired or replaced when it's damaged?

[Gayle]

It is best to replace the car engine block if it is damaged. Here are the relevant details: 1. Degree of damage: This depends on the specific extent of the damage. If it is simply burning oil, repair may suffice; if the damage is more severe (such as to the crankshaft, cylinder head, or cylinder block), repair is not advisable, as the installation process and cleanliness of a new engine cannot be matched by repairs. 2. Replacement: When the engine is damaged, it depends on which part is damaged—whether it is related components or major parts. If it is related components, they can be directly replaced; if it is major parts, you may choose to replace the entire engine.

[McReed]

Last week, my buddy’s decade-old Passat ran into this exact nightmare. The dealership tore it open and found a finger-length crack in the cylinder wall, with a repair quote hitting five figures—and no guarantee of a permanent fix. I advised him to just source a used engine instead. He spent 22k on the same model, and it was all done in three days, parts and labor included. In today’s market, cars with over 150,000 km really aren’t worth cylinder block repairs—welded fixes often lead to oil leaks later, and a full rebore with piston rings can cost half a new engine. Unless it’s a limited edition or a sentimental classic, you’re better off swapping the entire unit and updating wear-prone parts like the timing chain and water pump while you’re at it, saving yourself the hassle of repeat repairs.

[DeSophie]

Our repair shop dreads taking on cylinder block repairs the most. Last time we worked on a Buick with cylinder scoring, the owner insisted on saving money with a repair. Just boring the cylinders and replacing the pistons and connecting rods took five days. If you encounter issues like sand holes in the cylinder block or rusted-through water jackets, the welding strength simply can't meet factory standards. Nowadays, complete engine assemblies for mainstream models are easy to find - take Nissan's QR25 engine for example, a brand new one costs just over 30,000 yuan. Factoring in labor costs for removal and installation, it's only a few thousand more expensive than a major overhaul, plus you get a two-year warranty. We recommend regular car owners have the repair shop assess the damage extent - if the crankcase is already deformed, it's really not worth forcing a repair. A later engine blowout would hurt your wallet even more.

[Will]

The severity of cylinder block damage depends on location and depth. For minor cracks in the peripheral coolant passages, cold welding technology may still salvage it. However, if there are through cracks in the main cylinder walls, I recommend stopping repairs immediately. Last year, I helped a car club with a classic Focus engine repair - cylinder wall fractures caused connecting rod bending. Repairing just the block would cost over 8,000 RMB, while a refurbished engine replacement was only 12,000 RMB. Pay special attention to whether the crankcase is deformed, as this directly determines repair value. For vehicles with over 200,000 km showing cylinder block damage, it's better to upgrade to a higher-power engine from the same series.