Most people have heard of an Engine Overhauls, but not many really know what a rebuilt engine entails. Engines may need to be rebuilt for a variety of reasons. Like any other part of your car, its engine will deteriorate over time and eventually, major parts may be too worn to function efficiently, necessitating a rebuild.
When an engine is rebuilt, it is disassembled, and the block or lower half of the engine is machined back to spec. Piston rings, bearings, and sometimes pistons themselves are replaced. The surfaces on the insides of the cylinders are also refinished to ensure that the new piston rings seal tightly. The cylinder head is often refinished as well before reassembly and installation.
How do you know if your engine needs a rebuild? The most common sign that you might see is oil consumption and white smoke in the exhaust, especially before the engine is warmed up. This is usually caused by worn piston rings. More serious signs include metal shavings in the engine oil from worn bearings, and knocking or chattering from the engine bearings.
Two main reasons why engines may need to rebuilt are worn engine bearings and worn out piston rings. The moving parts inside of the engine such as the crankshaft, connecting rods, and pistons, are mounted on bearings lubricated by motor oil which allow them to move freely. Engine bearings are designed to last several thousand miles, but eventually, they will get worn out. This wear happens much faster if a vehicle is poorly maintained, for example if the oil is not changed often enough or it is run with a low oil level.
Worn engine bearings will produce a loud knocking sound, and may eventually break and damage the engine beyond repair, resulting in you needing not only an engine rebuild, but an entire replacement. Piston rings, on the other hand, are responsible for sealing in the gases created when gasoline is ignited inside of your vehicle’s engine. As they wear out, they will no longer be able to seal the cylinders properly, resulting in a phenomenon called blow-by. Blow-by refers to crankcase oil seeping past worn piston rings, and burning along with the fuel mixture in the cylinder. This often results in an excessive amount of smoke in the exhaust.
Engine rebuilds can be very expensive, and may not be the right choice for your vehicle. If you suspect that your engine may be in need of a rebuild, you might also want to consider swapping in a new or used engine in better condition, as this option may be cheaper. If you need help deciding if you need an engine rebuild or replacement, call your Certified Auto Repair Specialist today at (626) 793-2220. CARS is Pasadena’s number one vehicle repair and service center!