1996 7.3 jet sound at cold start up
 

My truck used to make a loud jet like sound at cold start as soon as you would touch the break it would stop. not making sound any more something to be worried about?

Its the turbo spooling up (or so iv been told) mine does it to, it sounds like a rush of air throug the exaust

Exhaust back pressure valve. It is actually blocking airflow on the outlet of the turbo. Creates heat and warms up truck. Perfectly normal so don't worry just drive it.

If under the same cold conditions, it isn't doing what you describe, then yes, might want to look into it. It's your EBPV Exhaust back pressure valve.... It should be doing exactly what you described...

It does it for only a second, Used to sit and idle with this sound until it warmed up. EBPV bad maby. Thanks for the reply

More then likely its your back pressure sensor that is bad, not the valve itself.