odd noise from 1k up

[navysnail]

hey, my car makes a noise like a school bus accelerating, kinda like a loud air filter. it is a 1990 240sx, stock, and it just started happening today. could it be the fan

[NISTECH]

could be. shut the car off and try to spin the fan it should just about free spin. if it is stiff or only spins about a half a turn then stops Its likely the fan clutch is locked up all the time.

[navysnail]

it is hard to spin right after i drive it but then it spins freely when cool. it happened twice today. once it started when i was at a light after it warmed up, the second time was after i pulled out of my drive way and the engine was warm. doesnt seem to hapen when its cold