Yesterday for the first time when I came off the freeway I put on the exhaust brake to slow me down and after I stopped I had this whistle sound. Come to find out it was the Jake brake that made the noise. Anyone else had this happen to them? Thanks, Jack

 

I've asked the same question about my Pacbrake. It appears to be normal from the responses I've received, and it sort of makes sense. All that air is rapidly trying to make it's way out of the motor, but it's being stopped by the butterfly plate. Some, of course, sneaks around the plate, causing the whistle/hissing noise. Sort of like putting your finger over the end of an air hose: the smaller you make the opening, the louder the hiss.

 

I had a pacbrake in my 95 for 9 years and never had any noise from it and had this one, Jacobs, for almost a year and this is the first time I heard it. It does not do it all the time. I need to take it for a run and see just when it starts to whistle but am to busy right now. If I find anything I will post it. Jack

 

Maccandy...Next time you start your truck when the engine is cold, put it in neutral and turn on the Jake. Is this the same sound you hear? How warm was the engine when you noticed this? I use mine a lot in city traffic, and after the engine gets good and warm, the hiss is not as noticeable at stoplights as when the engine is cold and sitting at a light or stopsign. I also use it a lot to warm up the truck faster on a cold morning, and then the hiss is very noticeable.
Hope this helps...
Steve

 

Check the clamps on the turbo and the brake. Mine was sounding just like a slipping fan belt - - one loose clamp and one broken clamp.

Oh, do it cold. OUCH

 

I am with FiverBob. Mine hissed like mad since the dealer intalled it and found loose V-band clamp between the turbo and butterfly valve. Tightened up the clamp and only have the hiss out the tailpipe now. If your noise is louder when it is cold, the clamps tighten up when everything gets hot. After a bunch of heating and cooling cycles the clamps can loosen up too.

 

Hiss is normal, whistle generally means a leak somewhere.

 

It is not a hiss it is a whistle. Only happens when hot. It's raining now and can't check the clamps but I will as soon as it dries up. Thanks Jack

 

My wife noticed the hiss first, then when it was hot it became a whistle or squeel - - I just knew it was a slipping belt. Wrong. I heard the whistle, but not the hiss. Open the hood when it is whistling with the brake button pulled - - you will isolate the sound to the turbo - - probably.

 

I tighten up the clamps and took it on a 250 mile run and no more whistle! Thanks FiverBob, Rock, & Hemi Cat

 

mine did the same thing. When I checked it one of the bolts holding the break onto the turbo had came loose.