I was just wondering about something, as my diesel now sounds louder than it did just a few days ago. I'm thinking it's because the weather got cooler, maybe, but I don't know.

But that beckoned the questions, why do diesels make the sounds they do anyways? A gas engine compresses fuel and uses spark. The diesel engine compresses the fuel a lot more, with no spark, making it ignite due to the pressure. Either way, the pistons go up and down to provide power for the engine.

Maybe it's just the extra compression and exploding of the fuel, rather than sparking it?

Jeff 1991 300d, 112k