What Causes Cylinder Wall Scoring (and How to Prevent It) – Jalopnik

On the outside, as an engine exhibits vibration, drivers may find the revs satisfactory. But inside, large metal pieces move frantically as each cylinder essentially undergoes a series of small explosions needed to generate rotational energy. There are tools available to help maintain order in the chaos, but that doesn’t mean problems can’t arise. For example, engine cylinders may misfire, or the cylinder’s inner metal walls may develop scratches or gouges in their surfaces.

There are a few culprits that could be responsible in this scenario, the first being oil – or the lack thereof. As a piston moves violently up and down in the cylinder, metal cannot rub against other metal because the friction and heat would lead to seizure. Between the piston and the cylinder wall there is a thin layer of oil (or at least there should be) that controls thermals and lubrication. However, compromised piston rings or oil that is simply too old can reduce its effectiveness, leading to direct metal-to-metal contact. These problems are further exacerbated if the engine is run hard at high speeds for extended periods.

Additionally, an engine that cannot properly regulate coolant will cause the temperature under the hood to rise, which can result in the expansion of some metal parts, such as the pistons. This reduces the important oil layer between the piston and the cylinder wall, leading to scratches and stress on the gaskets. A defective gasket can cause certain engine fluids to end up in the wrong places, further compromising engine operation. Fortunately, with some careful maintenance you can help prevent nicks in the cylinder wall.

Aged oil not only fails to perform its duties with gusto, but also absorbs common oil contaminants, sometimes thickening the consistency. This leads to it contributing to component build-up in the engine, reducing overall efficiency, increasing heat and potentially creating metal-on-metal friction. In some cases, analysis of the oil can identify traces of other metals, such as iron. This may demonstrate how the iron skirt around an aluminum piston can damage the cylinder wall in, for example, a Porsche M96 or M97 engine.

You should also keep an eye out for certain performance irregularities and have your vehicle inspected immediately if you notice them. Knocking or clicking noises when idling or accelerating, a sudden drop in power that causes your engine to have more frequent problems, and smoke coming from your exhaust are all immediate causes for concern. While these symptoms don’t automatically mean that your pistons are rubbing against your cylinder walls, they point to problems related to a lack of oil, loss of compression, and engine fluids getting into places they shouldn’t be. In some scenarios, these problems are all the result of cylinder wall scoring.

If your score goes beyond superficial scratches, depending on the extent of damage, you may be able to use a replacement liner as a new layer or add larger pistons after drilling a larger cylinder diameter. However, if the scratch has progressed to the point of creating deep gouges, cracks, or even a seized piston, the engine may be too far gone to save.