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FUEL TANK SEALANTS

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flyadive(at)gmail.com
Guest

Posted: Wed Jan 12, 2011 9:06 am Post subject: FUEL TANK SEALANTS

Hello Gaggle:



I have been fighting leaking fuel tans for a while.  The tanks are aluminum and sealed with PRO SEAL or the equivalent.  

Since my engine likes both AvGas and MoGas and MoGas has ethanol I would like a sealant that can stand up to both.

 Stop - I know about the trick of removing the ethanol from MoGas but that is only about 90% effective.  

I would like to run straight MoGas.

Would anyone out there have any experience in this area?

 



Thank you for the assistance.

Barry

  [quote][b]

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pete(at)usjabiru.com
Guest

Posted: Wed Jan 12, 2011 10:10 am Post subject: FUEL TANK SEALANTS

This will be long so please bear with me,

 

The question of solvents in auto gas is a good bit more involved than just ethanol.  We’ve recently had customers with fiberglass tanks and others with poly tanks who have had problems with auto gas even with no ethanol.  In some cases the auto gas has dissolved the tank sealant even though the sealant is supposed to be ethanol resistant.  In other cases the auto gas has reacted with something to form stringy mucus like strands that are quite good a gumming up the carb slide.  In two other cases something in auto gas coated the inside of the engine with a black combustion product that looked much like burned carmelized sugar (coated valves and valve guides resulting in stuck valves) At this point Jabiru USA is unable to pinpoint the cause of the fuel anomalies.

 

We have been investigating what may cause tank  sealants to dissolve and have been surprised at what we have found.  Anyone can find the same info if you dig hard enough and pursue the initial Google findings.  A week spent digging and following various leads will result in dozens of reports on auto gas quality issues.  We have seen reports detailing contaminants in fuel found in the Detroit area that included ethanol, methanol, MEK, acetone, toluene, TAME and MTBE.  Tank sealants are not designed to stand up to many of those contaminants.  

 

Additionally, many tank sealants are labeled as resistant to 10% or 15% ethanol concentrations.  If the gas – ethanol mix stays blended the concentrations may stay below those limits.  However – when some condensation enters the tank the resulting moisture combines with ethanol very readily (ethanol will combine with water much faster or more easily than with gasoline).  At some point the water ethanol mixture becomes heavier than gas and sinks to the bottom of the tank where it may remain with the ethanol concentration higher than 15%.  This concentration exceeds the tolerance of many tank sealants and can dissolve the sealant.  Since aircraft are prone to sitting for longer periods than cars, the ethanol mix at the bottom of the tank can be undisturbed sometimes for weeks or even months at t time while dissolving the sealant.

 

Again,  We are not even close to having many answers but offer these observations on what we’ve seen from auto gas use over the last 12 years.  We really have not been able to come to any solid conclusions other than to think about installing welded aluminum tanks (not an option for many planes).

 

On the other hand – we’ve yet to see a tank problem with the sealants we use when the aircraft is flown exclusively on avgas 100LL.  It costs a bit more but we view it as cheap insurance for our planes with tanks sealed with any of the commercial sealants out there today.

 

Pete Krotje

Jabiru USA Sport Aircraft, LLC

931-680-2800

www.usjabiru.com

 

 

 

From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of FLYaDIVE

Sent: Wednesday, January 12, 2011 11:04 AM

To: jabiruengine-list(at)matronics.com

Subject: FUEL TANK SEALANTS



 

Hello Gaggle:

 



I have been fighting leaking fuel tans for a while.  The tanks are aluminum and sealed with PRO SEAL or the equivalent.  



Since my engine likes both AvGas and MoGas and MoGas has ethanol I would like a sealant that can stand up to both.



Stop - I know about the trick of removing the ethanol from MoGas but that is only about 90% effective.  



I would like to run straight MoGas.



Would anyone out there have any experience in this area?



 



Thank you for the assistance.



 



Barry

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   [quote][b]

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flyadive(at)gmail.com
Guest

Posted: Fri Jan 14, 2011 3:22 pm Post subject: FUEL TANK SEALANTS

Hello Pete:



Thank you for taking the time to write up this information.

Aviation and even the automotive industry is in for a long up hill battle when it comes to gas containing ethanol.  There is a move afoot to INCREASE the ethanol from 10% to 15%.  This is going to be very disastrous as new cars (2011) have right in the operations manual: NOT APPROVED FOR 15% ETHANOL.  

  



I work with the GA type engines, Lycoming and Continental all the time.  The black coating you mention, I have seen, it forms with either Av or MoGas.  The cause has always been of two reasons:

 1 - Blow-By past the piston rings or

2 - Warn Valve guides. Or both.

The amount and hardness also seems (can't verify - not enough proof) to be because of the type of oil used.  Those with high concentrations of synthetic seem to produce a dryer, harder buildup.  And those with a 50:50 blend or no synthetic produce a oily COKE deposit.  

  



Your information about Detroit's fuel is quite, or should be quite earth shaking.  It is understandable to see ethanol or even methanol in gas.  I'll even accept TAME or ETBE, but MTBE?  That stuff has been mandated to be REMOVED from gas for at least the past four years.  There should not be any in the USA, unless the produces want a HUGE law suit.  Why would acetone, toluene or MEK be added to gas?  There are no reasons to do such a thing, the refining cost of those compounds is much higher than that of gas.  Sounds like a garage mechanic was using a disposal barrel and transfered its contents to a fuel tank.

  



Alcohols (ethanol & methanol) are hygroscopic, they adsorb the water.  The water does not adsorb the alcohols.  To increase the concentration of alcohol you would have to decrease the amount of gas, or decrease the amount of water.  Increasing the amount of water beyond the saturation point of the alcohol would keep the alcohol in suspension up to the 100% point and if excess water was introduced into the gas... Water being heavier than gas or alcohol would sink to the bottom. Caring the alcohol with it.  But, you can not get more saturation of alcohol to the bottom of the tank than the alcohol to water ration.

 I keep talking about % of saturation and ratio.  Let me elaborate a little.

If the gas has 10% alcohol and you have 10 gallons of gas then 1 gallon of the mixture is alcohol.  Ergo the ratio is 9 parts Gas and 1 part Water.

 If you want to remove the alcohol from the gas ADD 10% - (The same percentage of alcohol or slightly more.)  Of water to the gas.  The hygroscopic action of the alcohol will adsorb the water and ... Water being heavier than gas or alcohol will migrate to the bottom of the tank to be drained off.

 Sorry for repeating what has been addressed before.  I mentioned this because I had a couple of How To and To What Success inquiries.

I did get a lot of responses from the group to my query and THANK YOU gang.  There is only one product that I have not tried as yet.  I will bite the bullet one more time and try that one out.  The investment will be only about $27 so why not!

 



Barry  



On Wed, Jan 12, 2011 at 1:06 PM, Pete Krotje <pete(at)usjabiru.com (pete(at)usjabiru.com)> wrote:

  [quote]

This will be long so please bear with me,  

 

The question of solvents in auto gas is a good bit more involved than just ethanol.  We’ve recently had customers with fiberglass tanks and others with poly tanks who have had problems with auto gas even with no ethanol.  In some cases the auto gas has dissolved the tank sealant even though the sealant is supposed to be ethanol resistant.  In other cases the auto gas has reacted with something to form stringy mucus like strands that are quite good a gumming up the carb slide.  In two other cases something in auto gas coated the inside of the engine with a black combustion product that looked much like burned carmelized sugar (coated valves and valve guides resulting in stuck valves) At this point Jabiru USA is unable to pinpoint the cause of the fuel anomalies.  

 

We have been investigating what may cause tank  sealants to dissolve and have been surprised at what we have found.  Anyone can find the same info if you dig hard enough and pursue the initial Google findings.  A week spent digging and following various leads will result in dozens of reports on auto gas quality issues.  We have seen reports detailing contaminants in fuel found in the Detroit area that included ethanol, methanol, MEK, acetone, toluene, TAME and MTBE.  Tank sealants are not designed to stand up to many of those contaminants.    

 

Additionally, many tank sealants are labeled as resistant to 10% or 15% ethanol concentrations.  If the gas – ethanol mix stays blended the concentrations may stay below those limits.  However – when some condensation enters the tank the resulting moisture combines with ethanol very readily (ethanol will combine with water much faster or more easily than with gasoline).  At some point the water ethanol mixture becomes heavier than gas and sinks to the bottom of the tank where it may remain with the ethanol concentration higher than 15%.  This concentration exceeds the tolerance of many tank sealants and can dissolve the sealant.  Since aircraft are prone to sitting for longer periods than cars, the ethanol mix at the bottom of the tank can be undisturbed sometimes for weeks or even months at t time while dissolving the sealant.  

 

Again,  We are not even close to having many answers but offer these observations on what we’ve seen from auto gas use over the last 12 years.  We really have not been able to come to any solid conclusions other than to think about installing welded aluminum tanks (not an option for many planes).  

 

On the other hand – we’ve yet to see a tank problem with the sealants we use when the aircraft is flown exclusively on avgas 100LL.  It costs a bit more but we view it as cheap insurance for our planes with tanks sealed with any of the commercial sealants out there today.  

 

Pete Krotje

Jabiru USA Sport Aircraft, LLC  

931-680-2800

www.usjabiru.com  

 

 

   

From: owner-jabiruengine-list-server(at)matronics.com (owner-jabiruengine-list-server(at)matronics.com) [mailto:owner-jabiruengine-list-server(at)matronics.com (owner-jabiruengine-list-server(at)matronics.com)] On Behalf Of FLYaDIVE

  Sent: Wednesday, January 12, 2011 11:04 AM

To: jabiruengine-list(at)matronics.com (jabiruengine-list(at)matronics.com)

Subject: FUEL TANK SEALANTS  



 

Hello Gaggle:

 



I have been fighting leaking fuel tans for a while.  The tanks are aluminum and sealed with PRO SEAL or the equivalent.    



Since my engine likes both AvGas and MoGas and MoGas has ethanol I would like a sealant that can stand up to both.



Stop - I know about the trick of removing the ethanol from MoGas but that is only about 90% effective.    



I would like to run straight MoGas.



Would anyone out there have any experience in this area?



 



  Thank you for the assistance.



 



Barry

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