One problem related to loud engine noise has been reported for the 2008 Honda Pilot. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Honda Pilot based on all problems reported for the 2008 Pilot.
The #5 spark plug exploded and a piece dropped into the cylinder damaging the wall and piston. The 4wd/traction control light came on before there were any mechanical failures, I pulled over and tried to "turn off" the 4wd/traction, but it is automatic and since some wheels were losing power it would just come back on. Then the car started making a loud noise, so I ended up having it towed. When the dealer looked at the car they found the #5 (original manufacturer installed) spark plug had literally exploded and a piece dropped into the cylinder, ruining it. The whole engine had to be replaced, it has been a timely and costly experience. Even though my car had a 100k warranty under Honda care the engine they replaced mine with lasted only 2700 miles and now we are back to replacing that one, terrible experience.