I went to a friend’s workshop and he helped me bend up some 1.25×0.065 aluminum 6061-T6 tubing for some prototype coolant hard pipe to replace the really long rubber return hose with internal spring that ships with the M-tuned coolant reroute kit. The hose can be a pain to fit onto the radiator with the internal spring that keeps the hose from collapsing. And once again, packaging was a bit tricky as the flexy rubber hose could rub against the throttle bodies, alternator, fuel hoses, and/or body, which would wear a hole through and create a leak. You don’t want a completely rigid setup, either, as vibration would tear it apart. So a decision was made to bend some custom tubing in the hopes of making a coolant return pipe that would ease packaging around the throttle bodies at the expense of adding joints that could potentially leak.

 

 

It was a bit of a gamble bending thin wall aluminum as it can wrinkle, distort and even tear depending on the centerline radius and bend angle. Using annealed tubing would be best as it is soft and bends easily but that is really hard to come buy and ought to be be heat treated afterwards. 6061 T6, on the other hand, is rather ubiquitous. The only way to find out if it would bend was to try it. My friend converted the sketch into CAD and did all the figuring. Then we bent up two of them with slight variations and kept two tubes as spares in case these don’t work out. There was some slight ovaling at the bend but nothing to worry about. Flow rate will not be impacted. I will trim the ends to the correct length as I fit them to the car and I will also roll a bead in each end to keep the hose clamps from slipping off using my Earl’s EZ Beader tool, which is rather a one-trick pony but way cheaper than buying a slip roller or tube bead roller with the correct dies.

 

 

My hose clamps got soul! If they didn’t they wouldn’t be in here! Murray Corporation make these trick constant tension stainless steel hose clamps that keep your hoses from leaking whether hot or cold without having to crank down on them super tight. They’re also lined so they don’t cut into the soft radiator hose, either.

 

Much thanks to Adam (ada) at Bay Area Miata Drivers for the inspiration.