Morning all---We get quite a few emails and calls from builder/owners about the possibility of their silicone breather hoses collapsing at the bends and creating a potential fairly major situation. The engine needs to breathe, and if the breather hose is restricted, or collapsed, the possibilty of blowing out the crank seal increases, as well as other seals/gaskets. Alot of RVs have the molded 90* heater hose from Vans. While its good that is molded into the correct shape, the hose material isnt oil compatible. Over time is swells and becomes very soft and spongy. 306 style hose is oil resistant, but you have to do some makeshift 90*s to make it route properly.
Some of you have the Anti-Splat separator. Its a very good product, and it comes with a silicone hose. Its oil resistant, but its construction leave very little internal reinforcement. So if its over bent, it can kink and restrict and/or collapse, defeating the purpose of the breather. Worse, in flight, it could create enough crankcase pressure to blow out the crank seal, and potential engine damage from oil loss could occur. There are a couple of solutions. Yes, you can find pre-molded 90*s silicone hoses from the race car guys to make the routing better. It may not be long enough to work, so you may have to put several together. A simple solution is one we used back in the industrial hose days---an internal support for suction hose. Its s simple spring, that allows the hose to bend, but the spring supports the internal walls of the hose, and prevents it from collapsing. You can find these at alot of hydraulic hose shops, and some race car hose suppliers. It the length is short enough, even the aviation aisle at the big box stores may have what youre looking for.
Just measure the INSIDE diameter of the hose you are using, usually 3/4 or 1 inch dependent on the engine size, then find a spring with the OD of that size. Insert the spring and Eureka, problem solved. You may remember in the older days the lower radiator hoses on your car having support springs. Same Idea. Now those those of you that want the really cool factor and have a great spending limit on your AMEX cards, a convoluted stainless braid teflon hose solves all of those problems, including reducing your spending limit on the credit card.
Some of you have the Anti-Splat separator. Its a very good product, and it comes with a silicone hose. Its oil resistant, but its construction leave very little internal reinforcement. So if its over bent, it can kink and restrict and/or collapse, defeating the purpose of the breather. Worse, in flight, it could create enough crankcase pressure to blow out the crank seal, and potential engine damage from oil loss could occur. There are a couple of solutions. Yes, you can find pre-molded 90*s silicone hoses from the race car guys to make the routing better. It may not be long enough to work, so you may have to put several together. A simple solution is one we used back in the industrial hose days---an internal support for suction hose. Its s simple spring, that allows the hose to bend, but the spring supports the internal walls of the hose, and prevents it from collapsing. You can find these at alot of hydraulic hose shops, and some race car hose suppliers. It the length is short enough, even the aviation aisle at the big box stores may have what youre looking for.
Just measure the INSIDE diameter of the hose you are using, usually 3/4 or 1 inch dependent on the engine size, then find a spring with the OD of that size. Insert the spring and Eureka, problem solved. You may remember in the older days the lower radiator hoses on your car having support springs. Same Idea. Now those those of you that want the really cool factor and have a great spending limit on your AMEX cards, a convoluted stainless braid teflon hose solves all of those problems, including reducing your spending limit on the credit card.
