Galenkillam
Member
Background.
I purchased my RV-8 from the builder (who lost his medical and since has passed) 2 years ago. He ran 100LL in the left tank and auto gas in the right tank. I was told ethanol free but can?t confirm. I have used 100LL in both tanks since purchase. Prior to my purchase it did not fly for 5 years; however, was run regularly. I have put almost 200 hours on in two years with the biggest issue being I have needed to replace the right tank drain valve every few months as it gunks up. I assumed it was varnish from the auto gas. Nothing in the fuel strainer, no hiccups, no engine issues.
Now.
I pulled the right tank to install a flop tube and repair a seeping rivet before painting. When I got the tank off and open, there was clearly ?varnish? at and below the level where the fuel sat for 5 years I tried to remove the ?varnish? with acetone and MEK. Neither touched it. I tried a plastic scraper, no way. So I decided to wash the tank out with water before drilling/hole sawing my access holes in the back and to my surprise, water washed the gunk out. After over 2 hours of rinsing, the water is completely clear and the residue is completely gone from the aluminum. It looks great inside. I do think I am going to reseal the whole tank though.
Question,
What the heck is the gunk that developed from the fuel sitting for 5 years and why is it water soluble? It makes no sense to me.
I purchased my RV-8 from the builder (who lost his medical and since has passed) 2 years ago. He ran 100LL in the left tank and auto gas in the right tank. I was told ethanol free but can?t confirm. I have used 100LL in both tanks since purchase. Prior to my purchase it did not fly for 5 years; however, was run regularly. I have put almost 200 hours on in two years with the biggest issue being I have needed to replace the right tank drain valve every few months as it gunks up. I assumed it was varnish from the auto gas. Nothing in the fuel strainer, no hiccups, no engine issues.
Now.
I pulled the right tank to install a flop tube and repair a seeping rivet before painting. When I got the tank off and open, there was clearly ?varnish? at and below the level where the fuel sat for 5 years I tried to remove the ?varnish? with acetone and MEK. Neither touched it. I tried a plastic scraper, no way. So I decided to wash the tank out with water before drilling/hole sawing my access holes in the back and to my surprise, water washed the gunk out. After over 2 hours of rinsing, the water is completely clear and the residue is completely gone from the aluminum. It looks great inside. I do think I am going to reseal the whole tank though.
Question,
What the heck is the gunk that developed from the fuel sitting for 5 years and why is it water soluble? It makes no sense to me.
