There are a couple of signs that an engine rebuild may be necessary for your engine. The most recognisable symptom is oil consumption and excessive white smoke in the exhaust, especially when the engine is cold. This is normally a sign of worn piston rings. More severe symptoms include metal shavings in the engine oil (a common sign of dangerously worn bearings) and “knocking” or “chattering” from the engine bearings.
The moving parts of the engine (such and the crankshaft, rods and pistons) are mounted on bearings that allow them to move freely. These bearings are lubricated by engine oil. Bearings are built to last many millions of cycles, but like any other moving part, they do experience wear after time. This wear gets worse when a vehicle is poorly maintained and is run on low oil levels or the oil change schedule isn’t properly followed.
Worn bearings produce loud knocking and eventually can cause a destructive failure of the engine. Piston rings seal in the expanding gasses created by the burning of fuel within the engine. As Piston rings wear, they no longer seal the cylinders properly, resulting in a phenomenon called “blow-by.” Blow-by occurs when crankcase oil escapes past worn rings and is burned with the fuel mixture in the cylinder. Often this is the reason that older engines have an excessive amount of smoke in the exhaust.
What’s Done during an Engine Rebuild
At Australind Mobile Mechanics, when we rebuild an engine there are a few common steps we take to get your vehicle running smoothly again. First, the “short block” or lower half of the engine is removed and machined. We disassembled and cleaned so that the condition of the block can be properly assessed. Depending on the condition of the internal parts of the engine, the piston rings, bearings and sometimes the pistons themselves are replaced. The internal surfaces of the cylinders are also reconditioned to ensure that the new piston rings can form a proper seal with the cylinder walls. Finally, the engine is reassembled and installed back in the vehicle. Often the cylinder head is also reconditioned at the same time.