Exhaust brake hiss

[Sarge]

About a week ago I had a Jacobs exhaust brake installed by a Dodge dealer. I did so because l wanted the brake to interface with the ECM, and the brake by cummins seemed to make sense. Howerver, ever since the install, there is a loud hiss coming from the area of the brake wnen I turn it on. I do not believe that this is "normal". The hiss goes away when the throttle is applied, but comes right back when I let off. This is at an idle, or under way. I took it back to the dealer, but they said that it was normal to do that . I called the Cummins tech service line and spoke with a tech who confirmed that this is not normal. Now I have to call the dealer back and fight with him. Does anyone else have this problem with their Brake, Jacobs or otherwise? Any input would be greatly appreciated. Thanks, Sarge

 

[time1]

The hiss is normal. If you don't like the hiss just turn the brake off when you are at low engine RPMs or at idle. I usually turn mine off when below 35 MPH unless loaded. I can't see an advantage to have to down shift into second or first gear to get the RPMs high enough for the brake to have much affect.

 

[rubberneck]

totally normal, ive had a pac brake and a bd, and ive been in trucks with the jacobs, all make the hiss. They restrict the exhaust and that is what you are hearing. it goes away when you tap the throttle because the break automatically shuts itself off any time you give it any throttle

 

[John]

OK Sarge, here's a third opinion...



the hiss is normal for the reasons cited by the previous two members.



It sounds to me like the Cummins guy ought to be fired for being inept.

 

[RustyJC]

Totally normal. If a butterfly valve has the exhaust almost totally closed off, it's gonna "hiss" as the pressure squeezes around the valve at idle.



Rusty

 

[Sarge]

Thanks everyone, it threw me because the Jacobs web site indicated that the brake quote "operates virtually silent". I feel better now.

 

[klenger]

"Virtually silent" compared to the Jacobs engine brakes used on the big trucks. There's a topic on the Jacobs web site about "No Jake Brake" signs, and how they are illegal because Jacobs is a brand name and is discriminatory. I think that the article states that noise abatement laws do not apply to the exhaust brakes, but do apply to engine brakes.



See http://www.jakebrake.com/askus/faq/jbn.htm#FAQ9