Hissing noise at shut down???

[Lathe Guy]

Is it normal to have a hissing noise on the turbo side of the engine at shut down? It sounded like a raidator leak, but no dripping.

 

[JTeague]

More than likely the pressure equalizing in the A/C system after shutdown. Totally normal and nothing to worry about.

 

[JohnJoyce]

Or it could be just normal turbo spin down. On my 97 with straight pipes, I could shut down the truck and walk around to the tail pipe in time to hear the last *sigh* from the turbo. Kinda cool.

 

[CTDFreak]

Not sure how loud it is, but I notice you have an '05, and when I blew the plastic intercooler on my '05, there was a hissing air release sound coming from the turbo side of the engine. Have you noticed any performance or EGT changes?

 

[Lathe Guy]

It was the A/C.

I rarely turn off or start my truck with the A/C left on, (something my DAD taught me long ago ) but today I did and just happened to have the hood up and noticed something different.



I just went outside, turned it on and off several times.

A/C on - Hiss

A/C off - NO hiss :-laf



Thanks for all your replys.

 

[BTighe]

will turning the truck off with the ac on hurt anything. i always have it on and hardly ever shut down with it off.

 

[RankRam]

will turning the truck off with the ac on hurt anything. i always have it on and hardly ever shut down with it off.

The EGT's drop much faster with the A/C turned off.

 

[betterthanstock]

Turning off a/c 1 minute before shutdown helps dry out moisture and prevents musty odors. It may also make the belt last longer.

 

[Lathe Guy]

The reason I was given is the A/C compresser is under load. It puts extra strain on the starter.