Help!! Gas tank!!!

kevin27

kevin27

Well-Known Member
Aug 8, 2007
1,040
Winter Garden, FL
Boat Info
2017 Scout 175 sportfish.
2002 Crownline 202 LPX
Engines
Yamaha 90hp
Mercruiser 350mag mpi
I just found on my Crownline project boat while cleaning and inspecting everything in prep for the engine to go back in someone put a screw into the gas tank. Looks like some genius thought it was a good place to secure the zip tie for a replacement bilge pump.

So my question is do I have any reasonable SAFE options to repair or patch my plastic fuel tank? I looking for some real experience or knowledge on what to do with this not I think this or that with all due respect.

This is why I don't let people work on my stuff!
I find most of the time so called mechanics are just stupid, lazy, and don't pay attention to details. I can say that as a person who has been a commercial aviation technician for over 25 years. I wouldn't let these guys work on my lawnmower let alone a Boeing 757!

Now back on subject what can I do or am I skipping to the last step in the fault isolation tree and replacing the tank?

Thanks for reading and any ideas or replies.
 
20220822_102513.jpg
20220822_102458.jpg
 
So your not going to like my answer. If that tank is poly propylene like it looks like, nothing is going to bond to it enough to permanently seal the tank. While I have not done this because I ended up having a new tank made, I was going to drill a big enough hole in to the tank to put in an rubber expansion plug like this: https://www.napaonline.com/en/p/NOE...O4f8FUmhFKCoZpQvR8aAoblEALw_wcB&gclsrc=aw.ds&

This is one of the only methods to repair poly propylene I know of. The bigger issue is gasoline, you would need to find an expansion plug that was impervious to that. Like these: https://www.torq-n-seal.com/?gclid=...dm0qgLwfFPZ710LrfIsGB090CAMlgcGgaAqDMEALw_wcB
 
A quick search shows quite a number of products intended to repair plastic fuel tanks. But I have no direct experience with them :)

I have had neighbors repair fuel tanks in-place, however...

upload_2022-8-22_11-37-51.png
 
As @SKybolt points out you're not going to like this..

The only way to repair a poly tank is to heat weld it, this is how they are manufactured joining the two or more sections, if not a single piece blow molded.

With a water tank this is easy, with gas a whole nother level of prep is required.

You need to completely drain the tank, and then "gas free" the tank. This means filling it completely with soap and water.
Flushing that out and fill again, repeat until no fuel or fumes. If at all possible you want to pull the tank so you have the damaged side up and flat.

https://www.theweldingarc.com/how-do-you-weld-polyethylene-tanks/
 
hughespat57 said:
As @SKybolt points out you're not going to like this..

The only way to repair a poly tank is to heat weld it, this is how they are manufactured joining the two or more sections, if not a single piece blow molded.

With a water tank this is easy, with gas a whole nother level of prep is required.

You need to completely drain the tank, and then "gas free" the tank. This means filling it completely with soap and water.
Flushing that out and fill again, repeat until no fuel or fumes. If at all possible you want to pull the tank so you have the damaged side up and flat.

https://www.theweldingarc.com/how-do-you-weld-polyethylene-tanks/
Click to expand...

Can nothing on the internet be trusted these days??? :)

upload_2022-8-22_11-56-48.png
 
Stee6043 said:
Can nothing on the internet be trusted these days??? :)

View attachment 132648
Click to expand...

This looks like an option. Says for gasoline tanks. I will do some research. Thank you!

I just cannot believe someone could be so careless and stupid as to put a screw in the fuel tank when it's so obvious it's the fuel tank.
 
kevin27 said:
This looks like an option. Says for gasoline tanks. I will do some research. Thank you!

I just cannot believe someone could be so careless and stupid as to put a screw in the fuel tank when it's so obvious it's the fuel tank.
Click to expand...

Doesn't matter what it states, I can guarantee that it won't hold for long. As mentioned by @hughespat57 the tanks are welded and that is the only real way to fix, but it being a gas tank it is better to replace or try the method I suggested in my previous. You will have to drain the tank to be able to drill a proper size hole for the plug. But using any type of glue will not work, nothing sticks to poly propylene.
 
Polypropylene has a melting point of 320 degrees. Gasoline has an ignition temp of 536 degrees, so theoretically welding that small hole with a temp controlled gun should not be a problem. In some industry, I'm sure that sort of thing is done every day, but that's not information I have. Were it me with that problem I would start asking questions of people that weld that stuff for a living not a bunch of us jug-heads that many times are on our second snifter from our top shelf. Just know that the tank is not ruined, it is fixable. Talk to a tank manufacturer.
 
hughespat57 said:
As @SKybolt points out you're not going to like this..

The only way to repair a poly tank is to heat weld it, this is how they are manufactured joining the two or more sections, if not a single piece blow molded.

With a water tank this is easy, with gas a whole nother level of prep is required.

You need to completely drain the tank, and then "gas free" the tank. This means filling it completely with soap and water.
Flushing that out and fill again, repeat until no fuel or fumes. If at all possible you want to pull the tank so you have the damaged side up and flat.

https://www.theweldingarc.com/how-do-you-weld-polyethylene-tanks/
Click to expand...
Awh come on. Haven't you ever heard gas boil? :)

Many years ago, when I was 16, I had an old Fiat Spyder we where redoing. We where welding inserts into the rusted frame and heard a "gurgling" noise. Kind of looked at each other and said "what the hell is that" only to determine we where up against the gas tank with the heat of the welding torch. That was a real crap your pants moment. :)
 
Kevin, as a fellow AMT of 40 years I too do not let others work on my boat except the bottom painter and diver for cleaning and even then I don't like it.
I would look into plastic welding the hole. I bought a plastic welding kit years ago for repairing plastic interior and fairing parts. Since nothing will stick to the poly propylene I bet welding with a good sized electric soldering iron would seal it just fine. on the other hand if the screw is acting as a seal already and there is no sign of leaking, remove the zip tie and install a screw with a good fuel resistant washer and call it good.
I once found my wife's lexus 400 LS with a flat air strut and traced the issue to a pin hole in the air line to the strut. I used my plastic welder to fix the hole and it lasted at least as long as she drove the car and I bet for years after that.
 
You must log in or register to reply here.

Forum statistics

Threads
113,253
Messages
1,429,333
Members
61,128
Latest member
MinecraftRuSwilm
Back
Top