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Pulled my boat this week and noticed raw gas in my gas locker--turns out that my 3 yr. old 6 gallon Moeller tank was weeping/ leaking along the horizontal seam. I don't know if it maters but I just added SeaFoam to the gas in prep for fogging the engine for storage.

When I bought the tank from WM I never thought to check the construction of the tank or all the warnings posted on the tank but now I can attest they are necessary as the tank cannot stand up to internal pressures due to sun heating. There is a good reason to buy an OEM tank or at least find a tank that is seamless--hard to do if you buy from a picture on E-bay

Bob

Bob.. I am thinking you just had some bad luck.. Mine show no issues after 7 tears..

Bob,

Funny timing. Went out for a sail today and had a good time getting "out pointed" by TFlight on "D'Lei"...his jib enabled him to outpoint me with my 150 genoa.

But back at the marina I poured my 5-gal carry-on fuel can into my 12-gal Moeller tank. Then when I screwed my cap back on it was very loose. Turns out the black plastic "threaded flange" (proper terminology???) that is on top of the red plastic gas tank, to which I screw on the gas cap, has seperated from the tank.

So I guess I am done for the season...or at least until I get a new gas tank or two and new gas lines. The original owner had the gas lines permanently installed and run between the underside of the cockpit and the inner liner in the rear berth area. I think I will put gas tanks on both sides and use a new gas line that I can switch between tanks.

Cheers,
Jim
Sailing on König
Sailing on König YouTube Channel

bob,
Here in SW Florida the air vent always stay open and gas tanks covered with a towel so sun won't hit directly.
Sometimes these air vents are so small or items get in the air vent, causeing tank expansion.
sea Foam or any other gas additive will have nothing to do with tank or fitings falures.Any Sun thats hits a poly tank will cause expansion.
Any exposure to sun over a long time with air valve closed will rupture tank,or fittings.
Dave

bscott wrote:Pulled my boat this week and noticed raw gas in my gas locker--turns out that my 3 yr. old 6 gallon Moeller tank was weeping/ leaking along the horizontal seam. I don't know if it maters but I just added SeaFoam to the gas in prep for fogging the engine for storage.

When I bought the tank from WM I never thought to check the construction of the tank or all the warnings posted on the tank but now I can attest they are necessary as the tank cannot stand up to internal pressures due to sun heating. There is a good reason to buy an OEM tank or at least find a tank that is seamless--hard to do if you buy from a picture on E-bay

Bob

Dave,
My air vent was WFO
In the future I will not purchase any tank that is not one piece construction.

Bob

Divecoz wrote:Bob.. I am thinking you just had some bad luck.. Mine show no issues after 7 tears..

No bad luck for me--------Haaaaaaaaaaaaaaaaaa Haaaaaaaaaaaaaaaaa
Just a normal day at the dock

Bob

You know, the plastic on those tanks melts pretty easy... you could have simply re-sealed the tank by using a match to melt the plastic and re-weld it.

Here... hold my beer and I'll show you...

kmclemore wrote:You know, the plastic on those tanks melts pretty easy... you could have simply re-sealed the tank by using a match to melt the plastic and re-weld it.

Be sure to take the gas out of the tank first

Rick

c130king wrote:The original owner had the gas lines permanently installed and run between the underside of the cockpit and the inner liner in the rear berth area.

Woa! Gas lines inside the cabin are uncool. I hope I'm reading this wrong. The Mac by design has all the gas outside where it belongs.

RussMT wrote:

c130king wrote:The original owner had the gas lines permanently installed and run between the underside of the cockpit and the inner liner in the rear berth area.

Woa! Gas lines inside the cabin are uncool. I hope I'm reading this wrong. The Mac by design has all the gas outside where it belongs.

Nope, you are reading it correctly. That is the way the original owner set it up. He also has a nice fuel sender and guage set-up that works really well. If I go with another 12-gal tank I will probably install another fuel sender.

I will have to go back and research old threads on finding 12-gal tanks for an . Think I want a 12-gal on starboard and 2 x 6-gal on port side.

I think in my case the plastic just became brittle as it is nearly 7 years old...original owner bought the boat in Fall 2004. My fuel vent is always open.

Cheers,
Jim
Sailing on König Website
Sailing on König YouTube Channel

kmclemore wrote:You know, the plastic on those tanks melts pretty easy... you could have simply re-sealed the tank by using a match to melt the plastic and re-weld it.

Here... hold my beer and I'll show you...

Brings to mind a little ditty we used to sing as kids. It goes to the tune of My Bonnie Lies Over The Ocean.

My Bonnie looked into a gas tank
It's contents she wanted to see
She lit a match to assist her
O' BRING BACK MY BONNIE TO ME

So what do you do with a leaking gas tank
1) Weld it with a match--KaBOOM
2) Look into it with a match Byebye Bonnie
3) Have a few brewskies,fill it up and forget about it

Bob

Ahhhhhhh the proverbial Duct Tape?? Maybe Gorilla Tape would be better?? I did watch from a distance as My Friend " welded " a plastic fuel tank together..Inside his body shop with the machine that he uses to repair Rubber bumpers on cars.. Humm $50 When New but NOW ...Old Plastic fuel tank, in his $1,000,000.00 Body Shop not to mention His Body.. I was peeking from around the Big Pop Machine.. He did first, fill it so to speak with water and shampoo .. he swears the shampoo is what (Neutralizes?) the gas and its fumes.. Is it ? does it? I dont know ... But That Time..... it worked...

I was, of course, just joking about welding it with a match. *KA-BOOM*

However, having said that, yes, you can indeed 'weld' thermoplastic and I've done it many times. Steps to do your tank, should you wish to*:

Cleaning the tank:

• - Drain out all gasoline in the tank and allow to air out for 24 hours.

• - Put about a 1/2 cup of liquid detergent into the tank - any strong detergent will do (I use "Simple Green", but "Dawn" also works great) - but do NOT ADD WATER yet... swish it around and it will emulsify the remaining gas. Make sure you swish it and get all corners of the tank.

• - Now add *hot* water... REALLY hot... swish it all around and mix in all that detergent... shake...

• - Fill the tank with water, driving out any remaining fumes.

• - Drain, and repeat the detergent / water routine.

• - Thoroughly rinse the tank of all detergent and dry it out.

• - Your tank should now be free of any explosive gasses and you can 'weld' it. To be sure, give it the 'sniff' test - if it still smells strongly of petrol you should repeat the above steps until it 'sniffs' clean. (I've cleaned many a metal tank this way, prior to soldering or welding them, and it works.)

Welding Plastic:

• - For welding plastic I use a special "smoothing" tip on my Weller soldering iron - it looks like this:
  
  

• - Using other thermoplastic material as 'welding rod' (a milk bottle, cut into strips, works well**) you can soften the base plastic with the soldering tip, and then lay on the additional thermoplastic material and heat the base and material until they fuse... keep adding thermoplastic material until you've got a nice solid, mounded bead weld. Just as with any welding, penetration of the heat and welding material is critically important to the final strength of the weld.

You can also fix small tears in plastic bumpers this way... I've done it many times and the repair lasts just fine.

* (Although I'm sure I could fix a small seam separation like this myself, I take no responsibility for future liability if anyone else tries this!)
** (Polyethylene terephthalate (PET), which melts at around 260°C)

Thanks Kevin,

I have been wanting to do bigger and better ABS welding but did not want to spend big bucks for the welder to do them. That Weller tip is just the ticket.

Ken