Slosh Removal - Been There?

Been flying my RV6 with slosh since 1999. I built the plane 1989-99 and followed Van's directions to paint slosh over prosealed seams and to slosh the back cover. Now I am considering selling it and have started a slosh removal project.

I read the most promising looking threads under a slosh search here. Also wrote to Van's asking for recommendations. Got a note from Ken that Van's has no recommendations or materials for doing a slosh removal project. He said that it is such a bad job that I should just make new tanks. With these old (not pre-drilled) tanks I do not want to do that. Called Van's tech support and was lucky enough to have Scott pick up. He set me up with the covers for re-closing the back plate, new pro-seal, rivets, and the new pick-up tubes. I will also be doing the other tank service bulletins.

Have opened up the left tank by removing the access cover at the base and using a 5" hole saw to open up the outer four bays. There is a place where the slosh is coming loose on the outer rib by fuel filler. The rest of the slosh is solid - no cracks, etc. (Frankly, if I were keeping the plane I would continue flying it after addressing the small area where it is peeling. In view of the service bulletin, I am going to remove the slosh.)

My plan is to go at it with MEK, a Hobby Air respirator, gloves, Scotch Brite and stiff brushes.

My main question is what to do after I get the slosh off. I expect the process to do major damage to the existing pro-seal. Should I try to work in new proseal on all the seams or would it be OK to use a brush-able form of pro-seal or perhaps PR1005 on the seams?

Any tips from those who have been there will be appreciated.

I was really disappointed with Ken's response. Do any of you recall if Van's has some some guidance on this - maybe an RVator article (I have seen the Evans write-up referred to in the threads)?

Be cautious with regard to the MEK.

I cleaned off excess pro-seal from the top of my left tank with MEK prior to painting. This is after I had been flying for two years and it penetrated 14 rivets. The result was little paint blisters / bubbles over the top the rivets.

(I have just finished re-sealing the tank and will look to re-paint that tank after OSH.)

Yep, that gets at much of my reason for posting. I did not do this over the years because I thought the exercise might do more harm than good. I had not even thought of the MEK creating paint problems.

I guess being cautious means not letting it soak in too much. Hmmm.

Evan's Aviation Products

Evan has built over 1000 tanks over the years and has tried to remove slosh once, I believe he said. It was so much work and so much fumes from the MEK, he said he would never do another one. He can build you new tanks and will tell you how to make them fit. He said that this is the easiest way.

Steve

I did a small test to see if chemical paint stripper (klean strip) would remove slosh. It did pretty well.

If the paint stripper worked, why don't you just get some methylene chloride and half fill the tank and then rotate it. It is high vapor pressure and more dense than water, so to keep it you have to cover it with a layer of water. It is the active ingredient in good paint strippers. Do it outside and wear heavy rubber gloves. It will go right through some. Don't breathe it!!

Nasty stuff, but it really works. Some furniture restoration places have a large dip tank. You can order from chem supply houses, it is not flammable.

Good luck. Study, be informed, be careful.

My brother and I just completed an RV-4 that was started in the 80's and had sloshed fuel tanks. I tried MEK on the inboard bay thru the existing inspection panel, and after a day of work got no where. So we drilled out the entire back plate and carefully removed it, then brushed paint stripper on the white slosh, I then took it to Master Blaster in Auburn, CA to soda blast it. It took him about 5 min to remove all of the slosh. We then re-sealed all of the internal joints, and re-installed the back plate with pro-seal. We used Cherry-Max rivets where the back plate attaches to the ribs, and hand squeezed the rest. The results came out great with zero leaks. My brother is an A&P/IA and a very talented sheet metal guy, so that helped a lot, but if you are comfortable drilling out rivets, it made the whole process much easier than trying to work thru four small holes.

We've done several slosh removals. It's a little messy but not that bad.

Glasair180 said:

My brother and I just completed an RV-4 that was started in the 80's and had sloshed fuel tanks. I tried MEK on the inboard bay thru the existing inspection panel, and after a day of work got no where. So we drilled out the entire back plate and carefully removed it, then brushed paint stripper on the white slosh, I then took it to Master Blaster in Auburn, CA to soda blast it. It took him about 5 min to remove all of the slosh. We then re-sealed all of the internal joints, and re-installed the back plate with pro-seal. We used Cherry-Max rivets where the back plate attaches to the ribs, and hand squeezed the rest. The results came out great with zero leaks. My brother is an A&P/IA and a very talented sheet metal guy, so that helped a lot, but if you are comfortable drilling out rivets, it made the whole process much easier than trying to work thru four small holes.

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Wow.....sounds like that plan worked out great. I'm surprised you were able to remove the rear baffle (figuring this was a pair of 1st generation RV-4 tanks with the forward facing rear baffle?) without damaging and/or warping the baffle. How did you cut the pro-seal on the inside hidden edges of the baffle, including where the baffle touches the inner ribs, after you drilled out the blind pop rivets (AK-42-H)?