Q: Top engine makes knocking noise and car stutters when driving

Hello. A knock can be caused by a number of things. It can be as serious as an internal engine failure or it may be a misfire or a failure in the timing belt. When a knock occurs I always check the oil first. If it is low then there may be serious engine damage; I will typically drain the oil and look for any metal in it. If there is metal then the engine will need to be taken apart and inspected. If the oil is fine then I check the timing belt to make sure it is fine before I start it so I can then isolate the noise. If you are planning on having this knocking noise looked at, have a technician from YourMechanic come to your home or office to diagnose the knocking noise and replace the timing belt or make any other necessary repairs if necessary.