PacBrake Exhaust Brake Butterfly

[rotorwrinch]

After 26 years assembled and only 60000 miles of service, the Exhaust Brake on my '95 Dynasty is getting a refurb. 8.3 Cummings 250 hp with the mechanical injection pump. That said, here is my situation. I am replacing the pneumatic air cylinder and the Humphrey valve. The butterfly valve assy. has been getting the soak and spin treatment after being removed with the butterfly in the stuck open position. The $64 question is how freely should this unit turn? There is a risk in disassembling the unit if it is not necessary. Any experienced insight would be deeply appreciated.  I am near the point of moving the butterfly with my hand ??? The remainder of the system passed a rolling operational check.

[dl_racing427]

With the cylinder disconnected, and no spring force applied, I'd think the butterfly should rotate easily by hand, with only minimal drag.

There may be a return spring on the butterfly itself, instead of in the cylinder though.

[Notn2bars]

The butterfly should rotate easily.  Ours was frozen when we purchased our unit.  Took it apart as far as possible, cleaned and lubed it.  I decided to use Permatex Anti-Seize for lube due to it's high melting point of 1600 Degrees F.  Much higher than the recommended SuperLube.  Mine doesn't have a return spring.  It opens when the air is released.  Good luck with your project and God bless, Ed

[rotorwrinch]

Ed,

    Thanks for the reply. Would you kindly share how far you were able to disassemble the butterfly assembly? I talked to the tech line yesterday when they first opened. The tech advised against disassembly saying I would likely never get it back together in working order. I did not go into a personal history, but I have worked on everything from a stone axe to a turbine engine fuel control and would normally be a candidate for being the guy that can fix what others have no business touching. The assembly has already been mounted in a lathe and center drilled, milled and threaded for access and a zerk fitting on the blind bushing side. A firm believer in taking advantage of hard earned experience. Wanting for all I can absorb while waiting on parts. THNX Rj

[Notn2bars]

It was disassembled completely with the exception of removing the shaft.  Just took some photos before taking it apart.  Cleaned everything up and reassembled.  With your experience should be not problem.  I should have drilled and threaded a zerk fitting on the blind bushing side.  Will do that when I get bored.  It may be awhile before that happens.  

[rotorwrinch]

Thanks Ed. I will continue to soak the shaft and the bearing areas with some aggressive solvent with a PTFE lubricant until all the parts arrive. PACBRAKE/Super Lube is on the way. The unit has not gotten to the point of smooth and unfettered travel through the entire range. It may take having to disassemble it to solve that but that will be the last choice. Did you remove the set screw on the open staff end of the casting? It appears that may locate the shaft and keep the butterfly centered. If disassembly is required, I think it would have to come out. Again, Thanks.