Jake Question(s)

[MacHaggis]

Had a Jacobs exhaust brake put on a couple of weeks ago. DC wouldn't ship it, and dealer went to Cummins for it. The kit was short the gasket that goes between the turbo and the brake. Tech and I looked things over, compared the depth of the flanges on the brake and the old elbow, and decided to go ahead without it for the time being and see how it worked. I do now have the gasket.



What's a whoosh and what's a whistle? Install guide says I should hear a "whoosh"ing sound when the plate is blocking the exhaust, and that's how I'd describe the difference in sound when I walk around to the tail end of the exhaust. The install guide says that a whistle would indicate an exhaust leak. I don't have anything I'd call a whistle, but there's a pretty respectable hiss coming from under the hood when the brake is doing its thing. I've been under and over the joints at both ends of the brake (directly and with mirrors) and don't see any soot that would indicate a leak. Is this noise normal with the Jacobs? I could see it being a vacuum bleed or something, but thought they might have mentioned it in the troubleshooting instructions. Or maybe the hiss is what they call a whoosh?!?!?



I still suspect a leak, as my bareback mileage went up from right about 20 to about 21. 5. In any event, I'll slip the gasket in when I pull the wheel well to tap out the manifold for the pyro. Still, I'm wundrin'.



Discuss.

 

[FATCAT]

An exhause leak at the temperatures the turbo generates open you up to a engine compartment fire!!! Get that gasket in ASAP.

I think I remember some time ago that Dodge put a hault to installation of Jake E-Brakes becase of a problem with the gasket between the turbo and the brake until gasket was redesigned.

 

[jelag]

With the brake open, there should be no exhaust back pressure in the exhaust stream and little chance of a problem with a slight leak... . However with the brake on exhaust leaks can be a problem... . make sure the gasket is installed correctly... and after a couple of hundred miles..... several cycles to allow for the parts to move... go back and tighten the connection from the trubo to the exhaust brake... .



The only sound you should hear under the hood is the same sound you hear at the tail pipe... . remember the brake closes off 95% of the exhaust flow... If you have to check for a leak... do so only when the engine is cool and do it quickly before the parts and exhaust heat up to full operational temperatures... . exhaust leaks often show up when cold as the heating and expansion of the related parts will often help seal them.....



I have several trucks with exhaust brakes and you should no change in mileage with or without an exhaust brake... .



Hope this has helped... .