tobyw

Just installed my Pacbrake this weekend. Install went fairly well, had to wrestle the downpipe a bit to get things to line up properly, but other than that no surprises or issues. However, I'm looking for feedback from anyone else with a Pacbrake: are they supposed to hiss like mad when engaged? It makes sense I suppose, all that air trying to force it's way past that butterfly plate. I just wasn't expecting it, and could not find a single air leak anywhere, so I'm pretty sure that's the case but would like to hear from anyone else with one to verify my thoughts. Thanks!!

Hemi Cat

All the exhaust brakes I have ever dealt with will hiss when engaged.

Razor67

Yeah I had a pacbrake and they do hiss.... How is your compressor noise, mine was insanely loud and the dealership where it was installed told me that was just how it was supposed to sound so I changed it out with the bd brake much quieter

tobyw

The compressor is actually very quite. Certainly not audible over the hiss... I'd heard they used to mount the compressor to the firewall, but mine came with a nice bracket that bolts to the front of the motor. Between the normal engine noise and the hissing, you'd never know there was a compressor in the system.

bigblock2stroke

Isn't it a vacuum pump? I am confused by compressor? A/C compressor?

Did your PAC brake provide as much braking performance as the Jacobs unit? Just curious.

tobyw

Never been in a truck with a Jacobs exhaust brake, so I can't compare the two. All I know for sure is that with the limited "testing" I've done so far, you can tell it's there!

As for compressor vs. vacuum pump, the Jacobs works off of vacuum so it adds a vacuum pump on a new accessory pulley, and thus uses a new (longer) serp belt. The Pacbrake on the other hand uses compressed air, thus adding an electrical compressor. I have no idea why they utilize "opposite" systems, but I'm sure this will start a war over which type is better

twest

With Air and ECM bypass auxiliary tank ,the Air engagement is much Faster.

Hemi Cat

My truck has a pac brake and it is actuated with vacuum. I realize it is a 95 and yours is an 03. I'm sure the actuator cylinder is probably the same, but air pressure faster and more controlable.

taylorj

Bigblock2stroke,

I had the jacobs on my 2001 which I sold and now have the pac brake on my 2003. They felt the same to me in braking performance and have had no trouble with either. I chose the pac this go around for several reasons, price, ease of install, and no change of belt. If I was limited to one modification for my truck, the exhaust brake would be the choice. You get use to the hiss sound, I run mine all the time.

Johnny

tobyw

Taylorj - I assume your's also has the feature that engages the Pacbrake when water temp is below 170*F? The thing that is driving me nuts right now is, my truck apparantly never gets above 170*F!! Everytime I idle down, that sucker slams shut and starts hissing like mad!! It's difficult to judge actual water temp from our factory gauge, as the Cold mark is 140 and the Normal mark is 200... Mine usually runs about a needle width or two below 200, which I had previously assumed to be 185-190ish. Guess I was wrong... Have you noticed this, too? Of course I can just turn it off, but if my truck never gets warm enough for me to just leave the switch engaged, I'll basically be manually engaging that thing the rest of my life

taylorj

Tobyw, I have never noticed if mine shuts off at idle if my water temp is up. I have the shifter switch and just shut it off if I set too long. With my windows up I usually don't hear the hiss but but a lower tone with the brake on. If it is suppose to shut off like that and it is not I would guess it would be an ECM setting that would need to be turned on by the dealer.

Johnny