Cummins CTA 8.3 300hp

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3labs

Well-known member
Joined
Nov 18, 2006
Posts
57
Location
New Hampshire
Hi all

Have a question on the exhaust brake. Can you move the butterfly in the exhaust opening by hand? I had a crack in the flex pipe and removed it, and then tried to move the butterfly and I could not move it.It did not work when I picked it up on Sunday and I new it did not work because of the bad line.(I had to replace the air hose it melted from the hot exhaust)  I have read in the past that you have to keep the brake lubed up. I may unhook the air ram that works the brake but it is hard to get to. if I could find out if it can be
moved by hand with the ram connected if not  I will have to remove it because I cant move the butterfly at all. any thoughts?  :-\

Just a side note. I asked a cummins mechanic and he said that he never tried to move one  :eek:. Now I know why I do all my own work :)
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
48,834
Brian, the maintenance instructions in my PacBrake owners guide say "With your hands or a pair of pliers, motion the valve several times ...."  The latest online Drivers Guide reads a little differently.

I'm having a brain fart and can't recall if or how easily mine moved by hand last time I serviced the PB. You could, of course, have someone operate it from the dash while you look at it, assuming you have access via a hatch in the floor of your coach. You might want to apply some high temperature silicon on the valve shaft and the joints before trying to move it; This is also covered in the online guide.

I just stumbled upon the PB online Tuneup and repair tips. Scroll down to item #14 and you'll see they suggest removing the clevis pin from the end of the cylinder to allow mechanical actuation. However, you said it's difficult to get to.
 

Jim Dick

Moderator Emeritus
Joined
Feb 11, 2005
Posts
7,651
Location
Titusville, FL
It can be moved but it isn't like closing a door. It takes a little effort. When I had mine tested the mechanic applied 12V to the actuator. It moves easily then. :)
 

3labs

Well-known member
Joined
Nov 18, 2006
Posts
57
Location
New Hampshire
Thanks for the info I think I will remove the brake and service it. Now that I look at it closer it looks like it has not been used for some time and since I have it all apart it is less of a problem to just remove it and get a better look at it.

                                                                        Thanks Brian
 

StevenD

Member
Joined
Oct 25, 2010
Posts
5
Location
Sierra Vista, AZ
I recently had a similar problem.  The exhaust pipe split just after the turbo and the PacBrake back pressure never made it to the engine.  While I had the exhaust piping out, I physically cycled the air cyl that drives the butterfly valve you describe.  This should be lubed every 3-6,000 miles.  I use LPS Superlube, easy to find.  Your air actuator may be frozen or it could also be the linkage or even the valve pivots.  Fix it!  You need this device.  PacBrake sells parts and has great customer tech support.
 
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