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Working On My Six Pack

No, not my stomach...I'm afraid it's a lost cause.  I'm referring to the one on our coach.

Nice weather here, so I decided to chase some pesky air leaks.  First step: rebuild the front six pack (cuz it's easy to reach).  I marked everything carefully, removed the electric solenoids and air hoses, then detached the manifold.  Took it inside to work comfortably on my bench.

Disassembly is pretty easy.  I used a rubber strap wrench to loosen the "air valves".  There was some evidence of water intrusion (see photos), but nothing serious.  I was happy to see ZERO evidence of desiccant powder in the valves or air passages...but there was some dust and a bit of oily dirt.  Once I got started cleaning things up, I decided to have a little fun...you will see the result in the second set of photos.

I'm waiting on some parts to complete the rebuild.  When they arrive, I will put everything back together, then post a final set of photos, plus a list of part numbers.  Hope these will be helpful to those of you who have not yet tackled this project.

Re: Working On My Six Pack

Reply #1 –
More photos.  Notice I stamped the manifold inlet/outlet holes with the air hose numbers, to ease future maintenance work.

I'm waiting on 2 new pressure switches, plus a complete set of Parker Prestomatic air hose fittings.  When these arrive, I will finish the rebuild.

Note: Edited the second set of photos to correct the orientation of the manifold...

Re: Working On My Six Pack

Reply #2 –
Looking good Chuck! Bookmarking this thread for future reference. ^.^d
Don

Re: Working On My Six Pack

Reply #3 –
Very interesting.  This project is on my list.  I'll be watching.  ;D

Re: Working On My Six Pack

Reply #4 –
@Chuck,

Looking pretty. I'm going to need suppliers, part numbers, and MOPs! :) Nice write up.

see ya
ken

Re: Working On My Six Pack

Reply #5 –
 ^.^d

Re: Working On My Six Pack

Reply #6 –
Quote from: Chuck & Jeannie –
Once I got started cleaning things up, I decided to have a little fun...you will see the result in the second set of photos.


Given the appearance change, did you use something to remachine the o-ring sealing surfaces of the valve "ports" on the manifold?  Inquiring minds  ;) 

(I ask because it looks like there are scratches across one of them in the first set of photos (middle left on the vertical orientation) that doesn't appear to be there in photos of the second post)

Re: Working On My Six Pack

Reply #7 –
Chuck,
How do the check valves on the air in to the manifold look? Are you going to replace them?
JD

Re: Working On My Six Pack

Reply #8 –
Excellent documentation.

Look forward to final report with PN's.

Re: Working On My Six Pack

Reply #9 –
Quote from: Michelle –
Given the appearance change, did you use something to remachine the o-ring sealing surfaces of the valve "ports" on the manifold?
Good question.  The manifold body is made of aluminum, so you have to handle it carefully.  To clean up the o-ring seats, I used a very high-tech tool: a yellow No.2 pencil eraser.  Several of them, actually...  I keep a box of pencils in my shop for exactly this purpose - I find the erasers very handy for cleaning electrical contacts and light cleaning/polishing duties.  PLUS, if you sharpen the other end, you can write with them!

The rest of the manifold body was gently cleaned with green Scotch-brite pads, followed by a bit of aluminum cleaner-polish.  Ran a tap through the threaded holes, cleaned out the drilled passages with Q-tips, vigorously blew out all the holes with my air gun.  It is important not to leave any grit behind that might foul a valve seat.

The brass parts cleaned up easily with a brass wire wheel on my bench grinder.  The thick cad plated washers (that fit under the coils) were cleaned up with the wire wheel, which pretty much removed all the anti-corrosive finish.  I plan to replace these washers, if possible.

@John Duld:  All new o-rings will be used, of course, including the ones on the small nylon check valves, both of which are otherwise in like-new condition.  Full list of (current) part numbers to follow.

Re: Working On My Six Pack

Reply #10 –
Quote from: Chuck & Jeannie –
Good question.  The manifold body is made of aluminum, so you have to handle it carefully.  To clean up the o-ring seats, I used a very high-tech tool: a yellow No.2 pencil eraser.

 ^.^d  Exactly why I asked (because you've got a great example of how to do it right).  If a member isn't familiar with what even tiny scratches can do to o-ring surfaces, they might just think "shiny = good".  It's those scratches that transverse the sealing surface that'll get you.  (my dad was a model maker/machinist; I learned as a "yout".)  I once read about someone taking an angle grinder to an air sealing surface on a coach component - still makes me cringe.

Re: Working On My Six Pack

Reply #11 –
This goes back many years (OK, decades) but wonder if fine valve lapping compound would allow you to dress the surface properly? No transverse scratches that way.

Norm-- what do you think?

Re: Working On My Six Pack

Reply #12 –
Quote from: Michelle –
It's those scratches that transverse the sealing surface that'll get you.
I was most concerned about the two "top" (when the manifold is mounted on the coach) machined recesses.  (In my first post, see the first photo on the left, second row)  It looks, to me, like at one time a corrosive liquid (salt water?) was able to penetrate under the outer o-rings.  It took a lot of (circular) scrubbing with the eraser to remove the staining/etching in the metal surface.  I will take your advice to heart, and be sure to check all the sealing areas for any remaining transverse flaws, before I do the final assembly.

Since the two o-rings that fit under the brass valve bodies are completely "caged" by the design, I have elected to use high quality/high temp Parker red silicone o-rings.  I hope the somewhat "soft" (Durometer) nature of this material will help seal any imperfections that remain.

Re: Working On My Six Pack

Reply #13 –
ME? Depends on the scratch depth, the RMS finish required, and the surety that all lapping compound is removed.
Controlling depth without proper equipment (most don't have it) that is exactly perpendicular to surface and contact is equal all around is critical.
At Mercury Marine we roller burnished round shafts. It crushed the high points and sealed "pores" in the metal by crushing high points into valleys, such that the surface was quite smooth--sometimes a 10 RMS and also helped deter rust.

Re: Working On My Six Pack

Reply #14 –
While I wait on parts to finish my rebuild, here is a interesting little technical tidbit.  Before I started this project, I read all the pertinent existing literature on this Forum, and on Barry's Beamalarm.  Here is the most helpful reference:

HWH Leveling Valve Disassemble

If you order the O-ring kit from HWH, they send the large and small O-rings that go between the brass valve body and the aluminum manifold.  They DO NOT send (or even sell) the internal O-ring.  This is the one you find after you remove the stainless steel "shaft" assembly from the brass valve body.  At the very end of the above linked article, the internal O-ring is identified as being a AS568-019.  Based on this advice, that is what I ordered for my rebuild.

HOWEVER, after I finished the disassembly of all 6 brass valves (from my front manifold), I discovered something: the internal O-rings in my OEM valves are not conventional O-rings.  They are actually circular lathe-cut seals.  They have a entirely different "feel" to them - not as slick and smooth, but more of a "textured" surface.  And no, they aren't just round O-rings that were sqeezed into a flattened shape - they are definitely square (in cross section).

A little Google search led me to this info:
http://www.darcoid.com/images/uploads/pdfs/bulletins/TSD%205423%20(TetraSeal%20Circular%20Lathe%20Cut%20Seals).pdf

A careful measurement of these seals (with micrometer and machinist's rule) reveals they are actually the same size as the AS568-019 O-ring.  The only difference is they are square, instead of circular, in cross-section.  Since I want to stick as closely as possible with HWH's engineering specs, I decided to order some of these seals and try them instead of the O-rings.  If they don't work (i.e. hold pressure), I can always replace them with O-rings.

In all the reading I did, I never saw any mention of these "square" seals.  Has anyone else run across these in the process of rebuilding/repairing the HWH six-packs?  Or is this a new discovery on my part?  Comments?

Photos: Original HWH "square" seal on the left, new replacement AS568-019 O-ring on the right.

Re: Working On My Six Pack

Reply #15 –
Quote from: Chuck & Jeannie –
While I wait on parts to finish my rebuild, here is a interesting little technical tidbit.  Before I started this project, I read all the pertinent existing literature on this Forum, and on Barry's Beamalarm.  Here is the most helpful reference:

HWH Solenoid Valve Disassemble

That most helpful reference is was actually one of Steve's posts (and those are his photos) here on Foreforums.

Re: Working On My Six Pack

Reply #16 –
Chuck, I have seen these over the years and if HWH used them they must be available. I reckon they hold a higher pressure than the O type and hasten to say you cannot use the O rings in that groove as these would not hold any pressure due to the smaller cross section compared to the original. The surface area of the square one is much bigger than the slightly deformed O ring that fits into the groove.
JohnH

Re: Working On My Six Pack

Reply #17 –
  
                      Nice work and thanks for the documentation / I am sure it will be of great assistance to all who
                      attempt to repair their Six packs.
 
 

Re: Working On My Six Pack

Reply #18 –
Quote from: Chuck & Jeannie –
While I wait on parts to finish my rebuild, here is a interesting little technical tidbit.  Before I started this project, I read all the pertinent existing literature on this Forum, and on Barry's Beamalarm.  Here is the most helpful reference:

HWH Leveling Valve Disassemble

If you order the o-ring kit from HWH, they send the large and small o-rings that go between the brass valve body and the aluminum manifold.  They DO NOT send (or even sell) the internal o-ring.  This is the one you find after you remove the stainless steel "shaft" assembly from the brass valve body.  At the very end of the above linked article, the internal o-ring is identified as being a AS568-019.  Based on this advice, that is what I ordered for my rebuild.

HOWEVER, after I finished the disassembly of all 6 brass valves (from my front manifold), I discovered something: the internal o-rings in my OEM valves are not conventional o-rings.  They are actually circular lathe-cut seals.  They have a entirely different "feel" to them - not as slick and smooth, but more of a "textured" surface.  And no, they aren't just round o-rings that were sqeezed into a flattened shape - they are definitely square (in cross section).

A little Google search led me to this info:
http://www.darcoid.com/images/uploads/pdfs/bulletins/TSD%205423%20(TetraSeal%20Circular%20Lathe%20Cut%20Seals).pdf

A careful measurement of these seals (with micrometer and machinist's rule) reveals they are actually the same size as the AS568-019 o-ring.  The only difference is they are square, instead of circular, in cross-section.  Since I want to stick as closely as possible with HWH's engineering specs, I decided to order some of these seals and try them instead of the o-rings.  If they don't work (i.e. hold pressure), I can always replace them with o-rings.

In all the reading I did, I never saw any mention of these "square" seals.  Has anyone else run across these in the process of rebuilding/repairing the HWH six-packs?  Or is this a new discovery on my part?  Comments?

Photos: Original "square" seal on the left, new replacement AS568-019 o-ring on the right.
Caterpillar has a kit with the square seals so they must be available elsewhere. I am curious as to what you finally use and how it turns out. If you will post the part number it would be appreciated as I will be tackling the same issue in my coach.

Re: Working On My Six Pack

Reply #19 –
Those "o" rings are actually called " quad "0" rings. Used in many hydrlalic/air systems on tuna,tug,work boats.