tiger_hunt
Active member
More frequently on cold starts and occasionally on hot start I will hear a barely perceptable humming or droning sound that lasts for about 1 second. I think it is coming from the engine, but I am not sure. The sound occurs when the engine first fires up. I heard the same sound once recently when the fuel filter was plugged and the engine did not start. It made the sound after the ignition key was turned off. I have run B99 the last 50K miles. The head was replaced 20K miles ago because of a timing belt disaster. The engine runs fine, and has good power and fuel economy. Any ideas what could be causing the sound?