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  #11  
Old 07-05-2017, 11:03 AM
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RVbySDI RVbySDI is offline
 
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Location: Tuttle, Oklahoma
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Quote:
Originally Posted by Michael Burbidge View Post
I've had to remove my left tank twice. One leak was on the cover plate and one in the rear baffle.

I had an RV-expert and A&P friend help me fix the leaks both times. He used the tank test kit, (ballon, etc.) to find where the leak was. Pressurize the tank using the test kit, then use water and soap to identify where the leak is.

Fuel can wick like crazy. It is sometimes not at all obvious where the leak is.

The rear baffle leak was in the bay where the fuel fill hole is. My A&P friend was able to remove old, softened sealant, clean and apply new sealant through the filler hole. He fabricated some make shift tools. 100 hours later, the repair is holding up well.

I had blue fuel stains all along the rear bottom seam of the tank, as well as the inboard edge. It looked like it was leaking all over the place, but it turned out to be one small spot on the outboard bay.

I was very happy that we did not have to tear into the rear baffle!

By the way removing the 21 bolts, is not near as bad as it is hyped up to be, once you've done it. The second time, I had all the bolts installed in less than 30 minutes. There's only 2 or 3 that are painful, even with the pushrod still installed. I fretted over this for some time, and even hired my A&P friend to do it the first time. The right tools, as have been suggested is the key.

Michael-
Michael,
I truly hope your A&P was successful in stopping your leak. However, if one only removes proseal from the exterior of the tank and replaces it, I am very doubtful that will end up being a long term resolution to a leaking tank. That was the real reason I became such an expert at tank removal/repair. The air/fuel mixture that exists outside a leaking tank will never allow for the proseal to effectively seal off a leak. The leak will eventually resurface due to the chemical makeup of the fuel/air/proseal.

Good luck with your existing repair. I hope your situation proves my statements wrong.
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  #12  
Old 07-05-2017, 11:18 AM
Michael Burbidge Michael Burbidge is offline
 
Join Date: May 2006
Location: Sammamish, WA
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Default Interior fix...

The leak was fixed on the interior of the tank. The sealant was applied to the interior, rear, bottom baffle through the filler hole.

I agree that applying pro-seal to the exterior of the tank would not provide a long-term fix.

My main point is, that you need to find out where the leak is. Why cut holes in all the bays of the rear baffle, if the leak is only in one bay?

Michael-
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  #13  
Old 07-05-2017, 11:44 AM
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RVbySDI RVbySDI is offline
 
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Quote:
Originally Posted by Michael Burbidge View Post
The leak was fixed on the interior of the tank. The sealant was applied to the interior, rear, bottom baffle through the filler hole.

I agree that applying pro-seal to the exterior of the tank would not provide a long-term fix.

My main point is, that you need to find out where the leak is. Why cut holes in all the bays of the rear baffle, if the leak is only in one bay?

Michael-
Ok, gotcha. Very true as long as the leak is in a bay that is accessible. However, the only bay that is accessible without opening it up is the first inboard bay with its inboard access plate. If lucky enough to be able to reach through the fuel cap maybe you would be able to reach the interior seams with some difficulty in the outer most bay. Anything else though is going to require opening up the tank in some manner.
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  #14  
Old 07-05-2017, 01:21 PM
BillL BillL is offline
 
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Default I have heard of this, but - - -

Quote:
Originally Posted by RVbySDI View Post
Michael,
I truly hope your A&P was successful in stopping your leak. However, if one only removes proseal from the exterior of the tank and replaces it, I am very doubtful that will end up being a long term resolution to a leaking tank. That was the real reason I became such an expert at tank removal/repair. The air/fuel mixture that exists outside a leaking tank will never allow for the proseal to effectively seal off a leak. The leak will eventually resurface due to the chemical makeup of the fuel/air/proseal.

Good luck with your existing repair. I hope your situation proves my statements wrong.
More information please. I sent pictures, descriptions, and cross section pictures to a 3M engineer for their version of tank sealant. She had never heard of it and was skeptical of it even happening. I never got a good explanation.

So, if I took a bowl coated in inside with proseal, then dripped fuel into the bowl enough to just keep it wet, (maybe a wick) it will soften?

BTW- thanks for sharing your tank experience, I just tested my tanks (made 2001) and they passed with 42" of water in a manometer. Dang that thing is sensitive to temperature.
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Last edited by BillL : 07-05-2017 at 01:24 PM.
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  #15  
Old 07-05-2017, 01:43 PM
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RVbySDI RVbySDI is offline
 
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Originally Posted by BillL View Post
More information please. I sent pictures, descriptions, and cross section pictures to a 3M engineer for their version of tank sealant. She had never heard of it and was skeptical of it even happening. I never got a good explanation.

So, if I took a bowl coated in inside with proseal, then dripped fuel into the bowl enough to just keep it wet, (maybe a wick) it will soften?

BTW- thanks for sharing your tank experience, I just tested my tanks (made 2001) and they passed with 42" of water in a manometer. Dang that thing is sensitive to temperature.
Well, my 1st hand experience is that when the proseal (I believe I was using the FlameMaster brand) was exposed to air on the outside of the rear baffle and fuel made its way outside of the tank onto the surface of that baffle where the proseal was applied to the outside of the baffle flange there was a deterioration of the proseal over time. It was noted that even in areas where the proseal had properly cured there was a breakdown of the proseal. I observed proseal that was previously set and cured had broken down into a soft putty or peanut butter consistency and was allowing fuel to seep out from under that section of proseal.

It is my thought that a manometer is not a good tool for checking for leaks. Unless one can have a controlled environment where outside environmental temperatures and pressures cannot affect the reading of the manometer and in which one can isolate the cause of the rise or fall of the manometer strictly to the pressure inside the tank, I see little value in using it to check for leaks. The manometer, or for that matter, the inflated balloon will not be the beneficial tool for finding leaks. It will be the act of applying soapy water to all seams, rivets, etc. while applying small amounts of air pressure inside the tank that will allow one to find leaks. In that instance attaching the balloon is strictly serving as a relief valve for the pressure in the tank.

As for the manometer, as you said, it is an extremely sensitive tool that really is too sensitive for this task. One cannot isolate adequately all the variables that affect its movement to definitively state whether the movement would be do to a leak or to movement of temp/barometric pressure.
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  #16  
Old 07-05-2017, 02:57 PM
BillL BillL is offline
 
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Default Manometer

Yes, Steve I agree on the manometer, but my tanks were already installed on the wing. The test was at around 44" of water and the first tank had me goosey as it dropped 2" over night, but when depressurizing, the zero had dropped 2" also. The second tank I measured temperature. It dropped an inch overnight and also dropped temp. The absolute temperature ratio and another zero change (smaller) got it within .2" in 24 hours - airport barometer was no change.

The tank exteriors were bubble tested as was the fuel sender and plate and other areas I could access short of removal. No leaks there. For the rest, it may leak but my logic is that I will be flying and the removal won't be any more trouble than it is now, and I have proof that it needs to be removed.

One day I will get some 3M tank sealant, in date, and set up a test. If it fails I will be back on the phone with 3M and get to the bottom of it. With a control sample of the fuel too. How long did it take yours to leak again - in calendar time? i.e. how long should the test run?
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  #17  
Old 07-05-2017, 03:28 PM
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My problems persisted for approximately 2 years before I bit the bullet and cut the access holes for each bay. I would say in between each attempt was probably about 2-3 months before I again noticed blue staining from the leaks. I have now been 3 years since I made that last repair. Everything has been great for these past 3 years.
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