I have Mitsubishi Fuso FE-649. Just recently, when I accelerate up hills or when cruising down the freeway and accelerate over 65 mph I get this loud hissing sound like an air pressure relief valve has popped, as soon as I let off the accelerator it stops. I looked at the engine for obvious signs, the only thing I can figure is there's a plug at the back of the engine block the you can pull out by hand that is worn out? Any help is appreciated.
Thanks, Ray W
Friday, January 11th, 2013 AT 10:26 PM