On my recent trip across country the surge tank started leaking - and I'd replaced it just six yeas ago. The lousy mounting design coupled with the plastic part means stress cracks across the bottom. Another plastic one would be north of $200, the metal replacement over $350 if I remember correctly.
I started out with a simple sheet metal box design which could have been folded up out of .060 6061 and seam welded, but when I went to my local fabricator to talk about it he suggested a simpler solution - using standard tube and closing the ends.
I needed this quickly and we couldn't find any cheap 2x6 or 3x6 tubing, so we settled on 4x4, 1/8" thick, which is totally overkill. It holds about twice as much as the standard tank. I sort of consider this a prototype - if anybody needs a tank made I can hook you up with my fabricator and it will be improved. In the future, A 2X6 tube can be closed with the support angles, reducing the parts count as well as the amount of welding. If I had to do this again I'd also do away with the weld bungs and brass fittings - welding aluminum fittings on would save a considerable amount of money. I also need to figure out a better sight glass - perhaps two fittings connected with clear tube instead - more the 10% of the cost was the sight glass and weld bung. Final cost was around $400, I figure with some "value engineering" we could take over a hundred off that.
Making out of 2x6 and lowering as much as possible would also make it possible to fill without a ridiculous funnel contraption.
I had to trim the closeout panel a bit for the overflow hose and because I lowered the tank as much as possible - that took about a half hour with a sawszall.
I don't anticipate any more leaky tanks!
