Tank flush

[nwetzler]

Over the last few years, I've encountered a recurring issue...when draining fuel during my pre- flight, I would find very small (barely visible) yellow/reddish flakes in the fuel. Never more than a few flakes at a time, and never bigger than a grain of rice. Over the last 2 years, these flakes have all but disappeared, in fact I can't recall the last time I've seen them. Getting to the point, I've also had 3 incidences of a severely leaking carb over the last year. Where the usual "drip drip drip" would be, there is a steady stream of fuel. The last 2 times this occurred, I had the carb opened up and cleaned, and not only did the leak stop, but so did the drip drip drip I typically see, that I'm told is commonplace with the NA3 carbs. It's worth noting here that for the first 50 or so years of cub ownership, we never had a single drip of fuel. Then, in 2012 my grandfather ran ethanol enriched fuel and we subsequently had to have the carb rebuilt, among other things. So back to the point...after cleaning the carb, all goes well for a time...weeks, months, and then inevitably the leak comes back: this brings me to Sunday (Father's day). Starting my preflight, I turned the fuel on, and to my dismay the leak had returned (I'll attach a video if possible). Instead of going through the pain in the ass process of pulling the carb, just to satisfy my own curiousity, I started the engine, ran it for a few mins and then checked it again. To my delight, the leak was completely gone. So, in my mind, what's happening here is some dirt/debris is getting in the way of the needle seating properly, which is causing my leak. I'm guessing running it was just enough to clear the debris, and the seal was restored. Assuming I have an accurate assessment of what's happening, I'm guessing this debris is rust or paint in the tank. Again, assuming that's the case, is there any good way for me to clean the tank without pulling it? It's also worth noting that the needle/seat was re-lapped and adjusted the last time we pulled the carb, which as in the last resulted in about a month of no leaking. I hope I've provided sufficient info, but if not, feel free to ask. It's. 47J-3 a65-8, with a stromberg NAS3A1.

 

[bob turner]

 

[Renkou1]

 

[nwetzler]

 

[bob turner]

 

[cubdriver2]

 

[high time cub]