leadbullet13d

I have a 99 sd diesel. it has the banks 5" exhaust and the Edge Juice Attitude programer on it. It has 201000 miles on it. It just started to make this hissing sound at low speeds, or under very minimal throttle use. Like parking lot speeds, cruising, or just low speeds. It sounds like some body is releasing a tremendous amount of air out of the exhaust. Like a super loud SSSSSHHHHHHHHHHHH!!!!!!!!! Now i know what it sounds like when the turbo is spooling, so you jokers, save it for somebody that cares. But for those that actually know anything, please help me. I just put in new glow plugs, and a new starter, so i'm tired of spending money on stupid stuff. Thanks and i will hope to hear from you guys!!!!

Deagan

JOHULL

ok you ready for this? how about a bad brake booster. just a guess. I know at an idle it will irritate you with that air leak. the proper way to check it is to start the truck, then shut it off and wait about 10 seconds, the brake pedal should depress normally as if the truck were still running. if not it is surely gone bad. again this is just a guess so good luck.........Jody

Bl00ByU

My '99 F250 SD has hydroboost, which uses the power steering pump and fluid for its brake booster. Did you replace the breather when you did everything else?

Cuda_jim

EBPV Exhaust back pressure valve may be partially stuck shut.
Do you notice a lack of power when the sssssshhhhhh happens?