Timing belt systems are inherently noisy, but unusual or excessive noise is a sign of problems within the system. Turn it clockwise to unload the belt tension and then slip the belt off the pulley. The technical background on this issue is that the timing chain tension has lost its ability to keep the tension and the slack causes the rattle in the engine. If you hear rattling or scraping noises, it will certainly be a bad timing chain, since you have eliminated the operation of the other likely components. A timing belt can't rattle, there is nothing in a flexible rubber belt that can make any noise at all. Repair the issue and reinstall the belt if you can, or have a certified mechanic resolve the issue. If you have determined that the noise is from within the timing belt cover, then proceed to Part 5. I'm getting a "whining/whirring" noise when the engine is revved. There may be something else that's near the timing belt that does make a rattling noise, but I can't tell anything from the information contained in your question. Obviously I suspect the noise if coming from the new timing belt. I'd be pissed if 20-30k miles down the road the tensioner or pulley started making noise. Pfeifer Industries’ troubleshooting advice helps solve these problems. It’s going to cost around $500 to $1,500 to replace the timing chain or timing belt tensioner. The timing chain is an integral part of any engine, and without it, your vehicle is rendered useless. It’s not usually a good idea to drive a long time after you discover the engine making noise for this reason. The sound is a rattle that is heard just after the engine is started. The noise gets louder and louder and the engine is revved higher and higher. There is an issue plaguing Volkswagen 2.0 engines (with and without turbo) from years 2008-2013 which can happen at any mileage and at any time. The timing belt tensioner may make a rattling noise at a higher mileages. I have a 2008 Honda Accord V6 with 178,000 miles. Pfeifer Industries’ troubleshooting advice helps solve these problems. Start the engine. I can hear the noise regardless of if the car's in gear or neutral. The timing belt was just replaced a few days ago by a mechanic. I have never had a problem with my car beside the TPMS light which is not a big deal. Timing belt systems are inherently noisy, but unusual or excessive noise is a sign of problems within the system. However, when the timing chain is loose, it may cause a vibration inside the motor and that will produce a rattling noise as the engine idles.