Leaky Tank

[MXpilot1]

I have developed one of those leaky tank problems refered to in an earlier post. It is a very small leak (so far) which appears to be coming from around the inboard access plate. I plan to remove the plate and reseal it with proseal. Is this stuff a liquid or a paste or what? Should I apply some to the threads of the screws? Is there a gasket between the plate and tank? If the builder used proseal, how hard will the plate be to remove?

[LettersFromFlyoverCountry]

If the builder used proseal, it will be hard... real hard. I can't imagine getting in there without pulling the wing (i.e. tank) off but that's just me. I haven't had my wings on yet; just relaying my experience during building when complying with the SB from Van's.

Some people use a gasket, some people don't. I've used a gasket on one, didn't use it on the other. I didn't find it made much difference in terms of removal.

If you decide to take the plate off (as opposed to say using some of the "wicking" solutions that have been posted at various sites over the yeas), be very careful about having a bunch of crud getting into the fuel tanks. I'm not sure how that's avoidable.

A heat gun might not be a bad idea to soften up the proseal, although, again, I've never done it with tanks that have had fuel in them so I can't speak to how safe this would be.

I would try to confirm if the problem is coming around the plate or from the screws. It'll be relatively easy to fix if it's the screws. Remove, clean, put a bunch of ProSeal on 'em, stick back on.

[morlino]

Bummer.

It's more of a goo than a liquid or paste. It's sort of like working with brown bubble gum. I would NOT apply it to the threads of anything that I ever wanted to take apart. Vans ships a cork gasket. Apparantly, these can leak so many people just use proseal (or the new flamemaster stuff that Vans sells now) instead of the cork gasket. I've read on other threads that the access plate can be removed with a putty knife if it has been prosealed on.

[LettersFromFlyoverCountry]

I think it was Van's -- or possibly George Orndorf -- who said dip your screws in ProSeal before attaching... It creates a seal in the nutplate, and also creates a little seal around the screw itself and plate itself. I know some people use socket head screws here, but I had no problem getting the screws off (with the wings off) of the access plate even when sealed with ProSeal.

That access plate, though, is another story.

As Ken Scott tells it, the cork dries out over time and has a good chance of leaking; that's why people use ProSeal. The theory was also that if you use the cork seal AND proseal.... then if you have to take the access plate off...it's easier to get a putty knife or something in there to start prying.

However, with this method, you'll end up with cork shrapnel all over the place if you need to remove the plate...clean the area...and reseal. Not that ProSeal alone was any picnic, mind you.

[N28RV]

I agree with the previous observations. Additional 2 cents worth:

I have had two different tanks off for leak problems over the past 10 years, neither of which were built by me. First was for an upside-down installed fuel float. I agree, you really must take the tank off to do the job right. The first tank job went without a hitch. I used the cork seal and proseal. Putty knife, and MEK cleans up the area pretty well prior to installing the plate again.

The second job was for a leaky tank. I was a little niave the first time I attempted this repair. Thought the leak was from the screws, (which it was) and put everything back together again. Guess what...still leaking. Boy I sure do hate those 78 or so screws on the tank. Discovered it was also leaking at the leading edge where the inboard bulkhead meets. Most tanks seem to have a small void between the metals there. Opened it up again and cleaned up the inside and laid in some proseal on the inside and on the fittings too, just to be sure. Used cork seals both times, and yes, I dipped the screws too. They always came out with no trouble, and do provide a good seal. No leaks now for 2 years.

Dennis Mitchell
RV6A
Ft Collins, CO

[caryr]

check the screw threads leaking first before you pull the plate.

Put back 'button headed' screws w/ hex sockets and not the phillips headed. You can tighten them alot better in the cramped space.

JB Weld is just about as good a proseal if only have a couple screw heads leaking.

cary

[morlino]

My (old) Orndorf videos caution about getting sealant on the threads of the vent line and pickup fittings and he says not to use proseal at all on the cover plate or screws, just use the cork gasket. Of course my videos also include sloshing the tanks so things have changed a lot since they were made.

I've just avoided getting sealant on anything threaded so far. But I'm happy to hear that the screws will come out if sealant was used on them. This will make building my next tank easier.

I'm not sure which model you have or how much they differ but on my -7 there is a tooling hole in the inboard tank rib that is just barely covered by the reinforcing ring with the nutplates on it on the inside and the cover plate on the outside. It looked to me like this was a potential leak spot worth paying a little extra attention to. Might be worth checking out if you take the cover off.

[Kyle Boatright]

Originally Posted by MXpilot1

I have developed one of those leaky tank problems refered to in an earlier post. It is a very small leak (so far) which appears to be coming from around the inboard access plate. I plan to remove the plate and reseal it with proseal. Is this stuff a liquid or a paste or what? Should I apply some to the threads of the screws? Is there a gasket between the plate and tank? If the builder used proseal, how hard will the plate be to remove?

It isn't that bad, relatively speaking. Everyone (tm) had to remove their fuel tank access plates a year or two ago due to a fuel pick-up service advisory.

Sharpen the end of a putty knife and use it to cut through whatever the seal is - proseal, proseal and cork, whatever. It probably took me an hour a side, and I was suffering from a cracked rib, which really dialed up the fun-o-meter.

Proseal is a two part goo which starts out with the consistancy of thick icing and hardens to a rubber like consistancy.

[MXpilot1]

Thanks for the help guys. It looks like I have a slightly bigger problem. Upon closer inspection the leak appears to be farther outboard and the dihedral is causing the fuel to run to the inboard end of the tank. It looks like I'll need to pull the tank.

[LettersFromFlyoverCountry]

Do you think it's along the baffle?