In pressure testing my fuel tanks I found leakage at the top of the tank attach bracket on each tank, in the upper corners of the small “D” formed by the bracket and the tank leading edge (KIA pp. 18:04-05). The leaks were enough that I did not think Loctite would do the job, and the only other technique the factory recommends involves cutting access holes, which I was reluctant to do.
Research on this website uncovered a few posts that mentioned the possibility of sealing leaks by applying tank sealant diluted with MEK to the outside of the tank, and drawing it inward by reducing air pressure within the tank. An equal number of posts said that diluting tank sealant is prohibited, so the idea was a non-starter. This led to further research, including a discussion with a qualified chemist. I also mixed up a few test batches, which seemed to set in the usual way.
The method has been quite effective at addressing the leaks, at least so far. I used a hokey $7 HF “hand transfer pump,” which works both ways, and the manometer (water level) described in the instructions that come with the factory leak test kit. The maximum vacuum applied was 3/4 to 1 pound, which was enough to pull in the diluted sealant and stop the leaks. At one leak source I could actually see the sealant being drawn into the tank, and the water level in the manometer dropping several inches before suddenly stopping. The tanks are now proving airtight after being left pressurized to 3/4 pound for several days.
As mentioned, I was not able to find much discussion of this technique, and what I found was divided. However, in my case it seems to be working, and preferable to cutting access holes unless nothing else works. Maybe I just missed it in my research, but felt the technique was worth mentioning here.
Research on this website uncovered a few posts that mentioned the possibility of sealing leaks by applying tank sealant diluted with MEK to the outside of the tank, and drawing it inward by reducing air pressure within the tank. An equal number of posts said that diluting tank sealant is prohibited, so the idea was a non-starter. This led to further research, including a discussion with a qualified chemist. I also mixed up a few test batches, which seemed to set in the usual way.
The method has been quite effective at addressing the leaks, at least so far. I used a hokey $7 HF “hand transfer pump,” which works both ways, and the manometer (water level) described in the instructions that come with the factory leak test kit. The maximum vacuum applied was 3/4 to 1 pound, which was enough to pull in the diluted sealant and stop the leaks. At one leak source I could actually see the sealant being drawn into the tank, and the water level in the manometer dropping several inches before suddenly stopping. The tanks are now proving airtight after being left pressurized to 3/4 pound for several days.
As mentioned, I was not able to find much discussion of this technique, and what I found was divided. However, in my case it seems to be working, and preferable to cutting access holes unless nothing else works. Maybe I just missed it in my research, but felt the technique was worth mentioning here.