One problem related to loud engine noise has been reported for the 2002 Chevrolet Blazer. The most recently reported issues are listed below.
Immediately following purchase of a 2002 Chevrolet Blazer in August 2002, I noticed a loud roaring noise coming from under the hood which occured mostly upon startup when engine was cold and put into drive gear. This noise was also intermittently noticed after coming to a stop and then accelerating. By the time I drove it back to the dealership, it was not doing it. Since purchase, 2 replacement batteries have been installed. Service dept at dealership said alternator was draining the battery and replaced the alternator. Car is still doing this but dealer is unable to duplicate and saying loud roar is most likely normal. Now several acquaintances have said they had the exact same problem with their Blazers even though they were a different year model. Once the warranty runs out, this problem could add up to quite an expense.