Pac Brake Hissssssss

[CUMAPART]

I installed my Pac Brake today and everything went smooth. My question is when I turn on the exhaust brake I get a loud hissing sound. I know all the air is forcing itself through the small hole on the butterfly but this hiss is loud. I checked for leaks and can't seem to find any. I searched and found that other members have a whistle sound when brake is engaged but this is a loud hiss not a whistle. Maybe it's b/c the truck is 4in and straight piped? Any thoughts?

 

[Sticks]

That is the sound. You should be able to hear it real good at the tail pipe.

 

[ROADWARRIOR]

A muffler quiets it down quite a bit.



Dan

 

[jstyer]

Whsitle?

Have had one for 50K miles and mine never whistled, just hissed like h*ll. That's why it's a good reason to put two speed switch on shift lever to disengage when stopped rather than the switch they supply. Have 4" with a "muffler (if a straight thru is a muffler)" and it doesn't quite it much, although it is a little less than when I had it straight-piped.

 

[TPCDrafting]

When I took off the kitty, the hiss got a whole lot lowder on mine. The gear shift switch is a very nice feature. Pacbrake now makes their own switch. I've only seen a picture, but it looks like a rocker switch that has a little light. The BD switch on mine (looks like a two-speed switch) has developed a rattle. I had to put a rubber band around it and the shifter. It's more annoying than the hiss!!

 

[krs]

Hiss?



Neither of my Pacbrakes makes a sound anything like a hiss. Instead at idle they sound like the air intake with a Mega-cannon only louder - a deep throbbing sound. Both make a different sound when in use down a hill but it sure isn't a hiss. Are we talking about the same brake?