HELP! Stihl 020av fuel seepage around the fuel tank gasket.

[Stihlcutting]

Hi, I have a Stihl 020av that I have been trying to resurrect. It was given to me by a close friend and holds sentimental value. I have probably put more time and money into it than I should have but I have it running like a top. After getting it all put together and fired up It has developed a fuel leak from the bottom of the tank at the gasket area. I have replaced the gasket with new when I had it apart. I used copper spray-a-gasket on the new paper gasket thinking the extra sealer would help make a better seal. Maybe that is what caused the leak. I disassembled the saw today and found that the gasket appeared to sealed well to one half but the flange on the other half, along the bottom, wasn't sticking well. Upon inspection the only thing I see that could be causing the problem is some corrosion pits in the flange area. Has anyone ever had this issue and is there a repair, without replacing the tank half, that would be as close to permanent as possible. I am leaning towards anaerobic sealer or rebuild the surface with JB weld or even using three bond. I will attach pics from both halves. Any input on this would be greatly appreciated.

 

[singinwoodwackr]

Hi, I have a Stihl 020av that I have been trying to resurrect. It was given to me by a close friend and holds sentimental value. I have probably put more time and money into it than I should have but I have it running like a top. After getting it all put together and fired up It has developed a fuel leak from the bottom of the tank at the gasket area. I have replaced the gasket with new when I had it apart. I used copper spray-a-gasket on the new paper gasket thinking the extra sealer would help make a better seal. Maybe that is what caused the leak. I disassembled the saw today and found that the gasket appeared to sealed well to one half but the flange on the other half, along the bottom, wasn't sticking well. Upon inspection the only thing I see that could be causing the problem is some corrosion pits in the flange area. Has anyone ever had this issue and is there a repair, without replacing the tank half, that would be as close to permanent as possible. I am leaning towards anaerobic sealer or rebuild the surface with JB weld or even using three bond. I will attach pics from both halves. Any input on this would be greatly appreciated.

Try lapping that half on a skeet of thick plate glass using 220g paper. That will show any “channel’ that might cause a leak. The weight of the cover is usually enough pressure…don’t press hard.
Is the copper spray fuel rated? I forget

 

[Junk Meister]

Try lapping that half on a skeet of thick plate glass using 220g paper. That will show any “channel’ that might cause a leak. The weight of the cover is usually enough pressure…don’t press hard.
Is the copper spray fuel rated? I forget

Exactly what I was thinking as I was reading ... To get nitpikky I would do the other half as well. VERY Lightl to clean as well to reveal any high or warped places. A cast iron table saw top is a nice machined surface as well.

 

[singinwoodwackr]

Exactly what I was thinking as I was reading ... To get nitpikky I would do the other half as well. VERY Lightl to clean as well to reveal any high or warped places. A cast iron table saw top is a nice machined surface as well.

I wouldn’t use a tablesaw, they aren’t that flat

 

[Junk Meister]

Mine is and well within tolerance of what a gasket can absorb (the porosity of the pitting is the common culprit) . For me the table saw is right there.

 

[hacskaroly]

Upon inspection the only thing I see that could be causing the problem is some corrosion pits in the flange area. Has anyone ever had this issue and is there a repair, without replacing the tank half, that would be as close to permanent as possible.

Like stated above, lapping the tank half will be your best bet, definitely cleaning the edge to make sure there isn't anything causing a bump up that would prevent the two halves from going together flat with the gasket. If you do have some corrosion pitting that needs to be filled in, I have had good luck with JB Weld for filling holes and grooves. I've worked on a 075 and 031 both with leaking fuel tanks and had to split them, clean both sides really well and then reseat them with a new gasket. I used Permatex Aviation Form-A-Gasket (similar to the copper stuff you used) on both sides of the gasket and have not had a leak yet.