This is my email to Jacobs and somehow I received an answer from Cummins... ..... Larv
Details:
I have a 2004. 5 Dodge Cummins with your dlr. installed Jake brake. My
question is this: Some of the Dodge technicians (mechanics) have told me it isn't a
good idea to leave the Jake brake activated all the time (every day driving)
as I do. They tell me that will shorten the life of the Jake but they were all
pretty vague about it. One tech even told me that by doing that it could
damage the turbo.
What is your opinion on this issue?
Thanks in advance for your time!
And the answer from Cummins... ...
Summary: 04 Dodge Exhaust Brake
Solution:
Thanks for your Email message.
Not sure how you managed to get an exhaust brake installed, since Dodge does not approve them.
Cummins builds the diesel engines for DaimlerChrysler and Dodge supplies all the other components to build their trucks. Dodge previously did not approve the use of exhaust brakes on their trucks with automatic transmissions and in August 2004, advised that they have discontinued approval of exhaust brakes on any trucks.
Dodge handles all warranties on their Dodge Ram trucks with diesel engines and they have advised that exhaust brakes are not approved by Dodge. For more information about the Dodge product, we suggest Dodge customers, contact Dodge at:
"www.4adodge.com" or 1-800-992-1997 (DaimlerChrysler Customer Service).
As far as running all the time with the brake switch on, we have also heard both arguments on which is the best way to operate the exhaust brake. In our opinion, it is probably best to only use it when necessary, since Dodge no longer approves their use.
All exhaust brakes are basically a 'flapper' type, butterfly valve installed in the exhaust system, usually right after or behind the turbocharger. These brakes can be operated manually or can be set up to operate automatically. If the brake is not set up for automatic operation it is just a matter of flipping a switch on the dash to close the valve.
The exhaust brake switch needs to be turned on (valve closed), at the top of a hill, then as the vehicle proceeds down the hill, engine rpm and manifold pressures increase and the back pressure created by the exhaust brake helps hold the vehicle speed under control during downhill operation. Near the bottom of the hill or if automatic, when the vehicle accelerator is activated again, the valve in the exhaust brake should open for normal backpressure operation.
Exhaust brakes are designed to slow the vehicle during downhill operation. For instance, when you come to a steep downhill grade with a loaded truck, the brake should be engaged to keep the engine from overspeeding down the hill and to keep the vehicle speed under control. The use of an exhaust brake is not necessary during light or no load, operating on level or nearly level terrain.
The thing that makes the brake most effective is the amount of cylinder pressure that is being expelled out the exhaust. Therefore, to create high backpressure, the engine must have high manifold pressure and the only way you get that is at high rpm, such as going down a steep hill.
Applying the exhaust brake at low rpm, where there is little or no manifold pressure does not create any braking effort. The highest braking effort will be at 2500 to 2700 rpm or so on 12 valve mechanical engines and 3000 to 3200 rpm on 24 valve electronic engines, ie. high rpm = high manifold pressure = maximum braking effort.
One word of caution here, however, is to not let the engine rpm go too high. If rpm exceeds the rated speed for the engine, there could be major engine damage if the valves hit the pistons, so the maximum rpm should be kept at or below the rated speed of the engine. The normal use of an exhaust brake will have no detrimental effect on the life of a Cummins engine.
We thank you for your interest in Cummins products. Please let us know if you need assistance in locating the nearest Cummins-authorized Dealer or Distributor Service Provider. For assistance in locating a Service Provider, feel free to use Cummins North America Dealer Locator, which can be found on Cummins website:
http://www.cummins.com/service_locator/index.cfm
Please let us know if you have other questions and if away from your computer or have a time-critical request that needs more urgent attention, feel free to call us toll-free (from North America) at 1-800-DIESELS (343-7357).
Email direct: -- email address removed --
Regards,
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Customer Assistance Center
Cummins, Inc.
Columbus, Indiana, USA
Dodge does not approve them? What the he!!?
Larv
Attention: TDR Forum Junkies 
