Question1) My Hyundai accent GLS 1.5 (2001 Model), has engine knocking problems. This comes intermittently. When it is not there Engine works fine. What could be the reason?
2) For the same car I noticed a slight drop of Engine oil level,What could be the reason
Answer1. Without hearing the knock, knowing when it occurs, and knowing how it affects engine performance, I'm unable to give you reasonably specific information. If it's a light knocking that only occurs on acceleration, I suspect you're talking about spark knock. This could be due to excessive carboning of the combustion chamber, effectively increasing compression, insufficient octane (minimum 87), a malfunctioning knock sensor, or excessive combustion chamber temperatures (for a variety of reasons). If you're talking about something more significant, it could be just about anything in or driven by the engine, such as the a/c compressor.
2. Depending on how much oil you're losing, it's possible the drop is normal. First, you should check for leaks and repair any that are found. But all internal combustion engines consume a certain amount of oil. Most manufacturers (including Hyundai) consider usage less than 1 quart every 1000 miles to be acceptable. My personal opinion is that 1 quart every 500 miles is an indicator that there's nothing wrong, and more than that indiactes a problem. Even at 1 quart every 1000 miles, however, if it's being burned inside the engine, it's still probably not economically wise to perform repairs unless there are more pressing symptoms that need to be addressed.
