bandit_601948

hi guys ! I have a friend that has a 2001 Chevy s10 blazer and he has no 4 wheel drive at all ! he changed the switch on the dash and nothing ! the garage said it is a vacuum problem ! I read on the internet you can blow smoke into the engine to find a vacuum leak ! what else can he try if it's not a vacuum problem ? he would like to get it fixed before winter ! thanks guys !