Plastic Tanks are All Junk

[LaqueRatt]

Is this true? Picked up a Mirro Craft with a Seasense tank. Soon found it was a leaker. Fixed the leak in the fuel line, but the plastic elbow going in the top is stripped. It'll get pretty snug and then not leak, but soon it pops up a thread and starts seeping all over again. Think part of the problem is the tank is completely full, but I sure would like to eliminate the leak.

Was thinking of buying a replacement tank, but the reviews seems to indicate that the new tanks are even worse. Not only do they push gas out around the fitting and through the lines, but they blow up like balloons and stay that way? Think I'd be better off keeping what I have, which at least does have a vent.

Any ideas on how to get the elbow to seal? I'm thinking some sort of goo, like Permatex and then maybe some super small screws to sorta stake the fitting in place so that it can't move anymore. Anyone have any success doing something like this? I'm also thinking maybe I can get a brass fitting that if longer would get down into some fresh threads, but what to do about the pickup line?

Help please! I don't want to set my boat on fire or waste any more liquid gold.

 

[Scott Danforth]

going to assume that this is a portable tank

Not a big fan of the new EPA tanks.

 

[LaqueRatt]

Yep as portable as 40 lbs of gasoline is to lug around. LOL

I have 4 Permatex products on hand. Trying to decide what my best bet is:
Anaerobic Gasket Maker
Ultra Blue
Hylomar HFP
#2 Form A Gasket Sealer

It shouldn't take much it's just seeping a little bit. I also have JB Weld, but a bit iffy on it. Maybe around the top to keep it from moving?

 

[airshot]

Due to the material the tanks are made from, there is very little that will stick to it. The plastic tanks actually go thru much more rigoruos testing than steel tanks go thru. The problem is where ever threads are concerned, there is the weak spot. All the testing is not done in the area of the threads!! Early plastic tanks didnt have any threaded areas other than the cap itself, which is large enough that it is normally not an issue. But as they became more sucessfull, the mfgr started more threaded parts. Over many years of of using plastic tanks I have found a hose and a clamp ( double clamp if possible) is far better than threads. Is there any way to use a hose clamp or two and forget using threaded connectors??

 

[jimmbo]

There are many well made Plastic tanks, and some of the problems with leaky ones, is owner/operator induced. Some people are Ham Fisted when tightening Fittings, and threads in Polyethene are not very strong

 

[LaqueRatt]

Yes this was likely owner induced, but not this owner, the last one. Ended up using hot melt glue, as it's supposedly unaffected by gas. Also it dries quickly, unlike JB Weld.

Put a nice coating on the threads, then quickly snugged it back up to the point where it usually seals. Went around the plastic ring on top and the tank with the hot tip of the glue gun. Once both started to melt I mixed in a little glue and swirled it around a bit. So now it's all melted together and hopefully will never come apart. Figured what do I have to lose, the tank is junk otherwise.

 

[airshot]

Actually a good idea, never thought about a hot melt glue gun....let us know how this lasts..

 

[JimS123]

I bought a plastic tank in about 1975. It went into the trash shortly after.

I have restored several boats and always was able to find an old metal tank for cheep prices. A little elbow grease and some fresh paint and they all work like new.

I must admit m y Whaler came with a pair of Tempo plastics and they work OK. But if they ever need replacing I have a stock of old metal OMC tanks ready to go.

 

[airshot]

1975 is aboutvthevtime plastic tanks hit the market, the early ones were junk, most mfgrs had to exchange them for metal tanks. As complaints grew mfgrs were forced to redesign and the govt stepped in with safety standards. By the mid 80's plastic tanks were getting much better. The testing standards for plastic tanks are very rigorous today. I was involved in some testing in the latter 80's and what those tanks went thru was quite awesome. One of the tests was to fill with water then freeze, had to with stand a drop of 40 feet without cracking. Most metal tanks had the same test but very few could withstand a 20' drop. Another test was to pressurize until they exploded,....hard to believe but the plastic tank with stood a higher pressure than the steel tank. After the tank body was finally designed to withstand more than a steel tank, the mfgrs started adding small threaded connectors....these threaded connectors were not part of the testing now, only the body of the tank....early plastic tanks used barbed connectors which worked well but the tank seams were splitting open. Mfgrs fixed the splitting issues then added the threads......not a wise idea. Today the threaded areas are supposed to have much thicker plastic to contain more threads for better sealing. The brand name plastic tanks are well designedand fool proof if you remember they are plastic tanks and use good judgement when tightening threads. Now, so many are made in foreign countries that have none or very little quality control, so....you get what you pay for! A good example of this are todays I phones that people pay hundreds of dollars for. These are made in China and three out of every 5 fail quality checks when they get to the US. However, it is cheaper to have 3 of 5 phones fail than it is to set up a quality control inspection team to check the phones before they leave the country. Pretty much the same issue with todays cheap import plastic tanks.

 

[LaqueRatt]

Something curious about my tank is that there are about twice as many female threads in the tank compared to the fitting. Seems to me if the elbow was a little longer it would be much more resistant to stripping and popping a thread. It's not been in the water or seen any use yet, but it sat all day at near 90 degs with no seeping. I do have the cap slightly loose though.

Another question. Is it necessary to strap these things down? My MirroCraft has a nice pocket dead center along the transom, but I see no good way to tie it down. I have a strap across it at an angle, but it makes the tank lift and bounce a bit. I'm not sure if that strap is going to stay put or not.

 

[airshot]

I do not use a strap if the tank is in a secure area so it cant move around, but if the tank is able to bounce or slide around then some type of tie down should be used. A 6 gallon tank could be a 50lb missle comming at some one...not a good idea

 

[jimmbo]

However, it is cheaper to have 3 of 5 phones fail than it is to set up a quality control inspection team to check the phones before they leave the country.

It is sad that Management has that attitude

 

[Silvertip]

I've not tried this on a fuel tank but I have had success in fixing threads in plastic by buying a metal fitting, doesn't matter what it's for as long as the thread is the same. Heat that fitting with a torch and screw it into the port. The hot fitting should reform the threads. You don't want the fitting red hot. Just hot enough to melt the plastic.

 

[BWR1953]

I read somewhere that HDPE can be welded. May be worth looking in to.

 

[flashback]

I've not tried this on a fuel tank but I have had success in fixing threads in plastic by buying a metal fitting, doesn't matter what it's for as long as the thread is the same. Heat that fitting with a torch and screw it into the port. The hot fitting should reform the threads. You don't want the fitting red hot. Just hot enough to melt the plastic.

This is something that I will be sure to remember!
Thx

 

[airshot]

It is sad that Management has that attitude

China does not allow foreign countries to set up quality control, it must be done with their own people, that is why 3 out of 5 are junk!! Tiawan does allow there customer to set up QC within their country as well as design. Tiawan stuff has far better quality comming out of there country, which really pisses off mainland China!!

 

[jimmbo]

"Tiawan stuff has far better quality comming out of there country"

I would beg to differ, my latest Nikon, a D850, made in Taiwan, is the worst DSLR I have ever owned, it is a Real piece of Fecal Matter. It has been sent back to Nikon, twice. They claim it meets "Factory Tolerances". If it does, those Tolerances are wide enough to drive 2 or 3 Semis through, Side by Side. The last time, they cleaned the Sensor, since then, every picture it takes has a Spot on it.

 

[LaqueRatt]

That's an interesting idea embedding a metal fitting. I think they make brass reducer bushings that might be just the ticket for this. If my repair fails I'll look into this for sure.

As to plastic welding, that's basically what I do with the glue gun. It's not a crafts gun, it's a HD Sears Craftsman that I've had for years. Get all the plastic to a molten state, mix in a little bit of glue stick glue forming a composite of the 3 materials. I've done this many times with many plastics. As long as you can get the plastic to melt it's basically permanent. Used to repair cracked battery cases routinely this way back when I was working at a battery warehouse that sold reconditoned units. If I ever had one come back on me I don't remember when.

 

[DeepCMark58A]

I read somewhere that HDPE can be welded. May be worth looking in to.

HDPE is welded every day, many pipelines have welded HDPE

 

[BWR1953]

That's an interesting idea embedding a metal fitting. I think they make brass reducer bushings that might be just the ticket for this. If my repair fails I'll look into this for sure.

As to plastic welding, that's basically what I do with the glue gun. It's not a crafts gun, it's a HD Sears Craftsman that I've had for years. Get all the plastic to a molten state, mix in a little bit of glue stick glue forming a composite of the 3 materials. I've done this many times with many plastics. As long as you can get the plastic to melt it's basically permanent. Used to repair cracked battery cases routinely this way back when I was working at a battery warehouse that sold reconditoned units. If I ever had one come back on me I don't remember when.

HDPE is welded every day, many pipelines have welded HDPE

Good to know!