captron33
usa
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Joined: 10/17/2004
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Lets try this again! Need some help. Cummins 400 isl, spartan chasis 2006 travel supreme.
I guess next will be taking it to a tech!
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wolfe10
Florida
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Joined: 10/08/2000
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First, do you have an EXHAUST BRAKE (external to the engine) OR an engine compression brake (internal to the engine)?
If exhaust brake, what brand?
The Cummins ISL could be ordered either way, with the exhaust brake being less $$$.
When you turn on the brake and close the throttle, does the Allison shift pad change from "6" to whatever your pre-select gear is (often 2nd or 4th)? That is the first step in brake activation.
Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240
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larry cad
ohio
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Joined: 05/23/2004
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The exhaust brake on your engine is activated via a butterfly valve that is mounted in the exhaust pipe. The butterfly valve is activated by means of an air operated cylinder that pulls the butterfly valve closed which blocks that exhaust pipe. Connected to the air cylinder is a solenoid activated air valve. When the exhaust brake is called for, the air valve is activated which causes the air cylinder to pull the butterfly valve closed. When the air valve is closed, a spring causes the air cylinder to extend which opens the butterfly valve and allows the exhaust gas to flow out.
The solenoid that activates this sequence operates on 12VDC that is turned off and on as required.
What is happening within this system that tells you the exhaust valve is not working. The only reliable way of knowing it is working is to physically watch the action of the air cylinder when the brake is called to work. You can only do that by watching the brake mechanism when the RV is being driven, and brake is called for. You have to be there watching it!!!
You can put 12VDC onto the air solenoid to see if it actuates the brake while you are setting still, but this does not mean that the system from the on/off switch on the dash, or the brake pedal, or other factors are working.
I fixed a butterfly valve several years ago that had become stuck and wouldn't open/close. Had to take it apart, glass bead blast is to free it up to pivot.
There are many possible problem areas, and YOU need to check them out yourself and tell us what you find. Otherwise, you need to take it to a service shop and, well, $$$
Any questions?
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Crespro
SoCal
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Joined: 07/23/2004
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captron33 wrote:Lets try this again! Need some help. Cummins 400 isl, spartan chasis 2006 travel supreme.
I guess next will be taking it to a tech!
First, Brett and Larry know much more about exhaust brakes than I do. That said, when my 2005 400ISL exhaust brake failed after about ten years, on the theory that brakes are important, I replaced it with an upgraded model.
Crespro 2021 Grand Design 310GK-R, 2020 F250LB, 7.3L, 4.30, Reese 27K
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keefr
Edmonton
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If it's a PAC brake, a likely cause is lack of lubrication on the pivot. It's not difficult to remove the unit, and if it can be freed, great. I had to have the exhaust brake replaced on my motorhome shortly after I got it, and it wasn't hugely expensive. I subsequently replaced it again with an upgraded brake that is designed to be effective at lower engine rpm. Again, not a huge expense.
Never argue with an idiot - they drag you down to their level and beat you with experience. - George Carlin
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wolfe10
Florida
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As you can see, we need more information to be of assistance.
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Blaster Man
USA
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I had an 09 Allegiance with an ISL 400...it had a two stage engine brake...not an exhaust brake.
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larry cad
ohio
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Blaster Man wrote:I had an 09 Allegiance with an ISL 400...it had a two stage engine brake...not an exhaust brake.
Uhhhhh........gee Thanks!
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Ray,IN
IN, USA
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Joined: 03/22/2001
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Blaster Man wrote:I had an 09 Allegiance with an ISL 400...it had a two stage engine brake...not an exhaust brake.
It would sure help if captron33 also told about his MH and type exhaust brake.
2000 Winnebago Ultimate Freedom pushed by a 2013 Chevy Silverado K1500 And so, my fellow Americans: ask not what your country can do for you — ask what you can do for your country.John F. Kennedy 20Jan1961
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captron33
usa
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Spartan confirmed i have a 2 stage exhaust brake., based on my vin number.
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