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Full Version: HWH 6-pack manifold corrosion?
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Has anybody had a problem with the 6-pack manifold corroding?  A guy on the Foretravel forum just posted the following and another guy had a similar problem and had to replace his manifold.  Gordon (Bestgenman) did a great job of moving his front manifold to the front basement compartment.

"Upon pulling our front six pack, it was hard to miss some heavy corrosion near the top of the port side, starting where it makes contact with the steel mounting bracket. Intergranular corrosion, a term I had never heard of until Jet Doc made mention of it in another thread. There was also some lighter corrosion in a few  places on the valve side, including the spot faced area under the outer o-rings for both lift solenoids. This corrosion is porous. Even if a good seal is obtained by the o-rings, air would likely migrate through through the corrosion. Being these manifolds are made from 2024 alloy, welding is not an option. What to do?

IMO, the only reliable fix is to replace the manifold, or remove all of the corroded material. Using a mill, I took a minimal cut on the mounting face, removed a fair amount of material on the port side, and, since I don't have the proper spot face tooling for the valve side, milled that entire side with an end mill. Although the o-rings WILL seal to a milled surface, (been there, done that, many a time) I took a fine table stone to it for good measure. For areas with smaller spots of corrosion, not where a sealing surface is, I used a die grinder with an oval single cut burr. The limitation of how much can be removed from the valve side is dictated by clearance between the raise valve spigots and the two isolation check valves under them. If too much material is removed, the spigots will interfere with the plastic check valves. I needed to remove .045" form the valve side, and that's pretty close to the limit. YMMV. Anything more than a light cut on the valve side will require a re-chamfering of the six valve holes (to accommodate the fillet radius on the valve spigots) and re-tap the 1/2"-20 holes to the original depth with a bottoming tap. This manifold needed an additional half turn of the tap in order for the valves mate up. After machining, I soaked the manifold in vinegar, overnight, and then washed in soapy water, rinse ...blow dry with air gun.

While the manifold was available, I reverse engineered it. Crude (but accurate) drawing on hand, should the need arise to make them in house. BTW, on our coach, the front and rear manifolds appear to be identical, though I didn't verify that 100%"