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I suspect i have a muddobber somewhere between the fuel tank and engine. Any good ideas how to probe through with some type of brush or something?
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This is the best I can offer & I can empathize with your dilemma. We had a mud dobber fill the two fuel lines to a tank but we were able to pull the lines off to clean them. First encounter with those buggers so every line end got a piece of tape until everything was connected.
Our mud dobber amalgam was really hard material and would not wash out with water. I was stumped for a bit and then decided to try a piece of the wire rope cable left over from the controls. I opened one end so it looked frayed cable to make a bore cleaner. I worked the frayed end into the fuel line and spun the cable with a drill working it back and forth. That happened a while ago. I think I put a piece of electrical shrink tube about 2" or so from the end to limit the frayed and a piece on the drill end. I worked it back and forth until I could see that the line was clean. You could probe the lines with a small diameter blunt cable to determine where the blockage is then mark the cable. Mark the frayed cable at the same point so you can work the bore cleaner back and forth in that same area. Flush the lines with gas as the matter will come out at the gascolator. It will take some work but it will come out. I don't know how far in they will go into a fuel line but ours was within the first few inches. Maybe use a very small diameter cable so you do no harm to the fuel line bends. Our fuel lines had sweeps for bends so the homemade bore cleaner went through ok.
Last edited by Glenn Patterson; 03-02-2018, 09:57 AM. -
What affect would all that scuffing have to the strength and flow characteristics?Comment
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The fuel lines looked ok when I was done as we could have fabbed new pieces. The cable expands to the diameter of the fuel lines and is not that aggressive. Mud dobbers do not do much for the flow characteristics. If the entire length of the line was scuffed then it would be an issue.
An alternative that may work would be to level the fuselage to prevent pockets & disconnect the lines at the gascolator and at the fuselage exits. Then back flush with water for an hour, let it soak and repeat a few times. Put tubing on the top to direct water away. Blow the lines out with compressed air top down, and repeat a few times to make sure they are dry. Could finish by running 70% isopropyl alcohol through as a rinse as it will take away any water and evaporate.Comment
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Would you think those scratches were deep enough to catch a finger nail? If they weren't inside a tube, that is.Comment
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There was some fine scratching but nothing alarming. The cable has to rotate in the direction as if a person is trying to tighten the wire strands so the wire drags & travels a little easier.. If drill spins against the grain then there is a real chance of strands digging in & unwinding to possible really jam. If person was really concerned with scratches then draw fine sand paper over the cable end to take off any sharpness. David could bend a piece of tube to replicate his tightest bend and give the cable a trial to see how works.
Soaking the lines for a day or two may break the amalgam down so it may flush out as a more gentle solution. The mud dauber material really sticks to the inside of the tube.Comment
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I would consider disconnecting and hooking up a hose with a temp rubber pipe, then flush with running water for a few hours. Just spit-balling here.
Obviously flush with fuel before reconnecting.Comment
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I think I'd blow it out with compressed air first. Then blow a string through the line. Tie a small piece of cloth (like a .45 cal swab) to the middle of the string and oil the swab. Pull the swab through, each way. Change the swab and repeat the process. Do this until the swab comes out clean.
BillComment
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What are the thoughts about using water to test for leaks, flow rates, or as a flush? I was thinking there's not much that would be affected by it, maybe pull the gascolator screen? Just seems safer and easier than using actual fuel, especially in a shop or hanger environmentComment
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Originally posted by Archer39J View Post
Using water for pressure testing is standard practice at industrial installations and in engineering labs for all manner of equipment.
Provided the water is clean and so is the metal surface, then it creates few problems. If there's any electrolytes around, beware.
I believe all the fuel fittings and lines should resist corrosion from clean water. The gascolator screen too.
I think water is thicker than fuel, so might be less than ideal for finding leaks. Provided the fittings are tightened correctly, leaks are pretty rare in my limited experience. If the fittings are not tight enough they almost always leak.Comment
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