Gas Tank Check

[Captin_Kirk]

I statred to clean up my sailboat that I just bought and I could smell gas. I looked in the engien compartment and although it was kinda dirty I dismissed it as the source. After locating the location of the tank, I lifted up the inspection hatch and the smell was really strong.

What I found one of the connections was real loose. I decided that tomorrow I am going to pull the tank and check it for leaks, and take that time while it is out of the boat to clean the area where it is located.

My question is two fold:

1) what is the best way to test the leaks. (Fill with water? The only problem with that is I live in Canada and it is winter so can't do it outside. Also what do I do with the gas water when I am done? can't really just dump it om the ground.

2) What is the best cleaner to use to clean up gas/oil? Household preferable.

When I put the brass fitting that is loose back in, can I use teflon tape to seal the connection? Does gas and teflon tape get along. (I realize that is 3 questions )

[ConradG]

Houshold cleaner that has worked reasonably well for me with oils is Simple Green.

Get a bottle of thread sealer. Thick goopy yellow stuff made for the job.

Seal and tighten the fitting and fill with gas. If theres a leak you can pump/siphon/dump it back into your contaiers and avoid having to deal with the water mix mess.

While the tank is out, if it is metal, clean and paint it well because you might not want to have to deal with it again....

My two cents..My third would be to get away from gas all together as it is dangerous stuff compared to diesel but that's another kettle of fish. Good luck!

[James S]

diesel is excellent for checking for leaks.
Man-o-man you want to be so very careful with gasoline on board...those fumes can turn your boat into a bomb.

[hugosalt]

I second using much caution when it comes to gas fumes very
volatile...if you don't go with above suggestions on checking for leaks, try garden type pressure sprayer. Seal nozzle into tank
along with outlets, pump sprayer to pressure, use water bottle
on outside of tank, look/listen for hissing and bubbles.
Again don't make a bomb...clear all fumes first!

[ConradG]

I think he was talking about removing the gas tank to tighten a fitting and see if there are any leaks. Although some of us won't even drive cars that burn gas, those that do don't worry about filling tanks, they just do. If you see no evidence of a leak other than the loose fitting, I wouldn't think twice about just filling it (out of the boat and outside) to see if there are any leaks.
I would caution against presurizing any tank that has any gas or fumes in it. Static elec from plastic, fiber hose and you have a bomb! When I have made tanks, I have presure tested them, but with water. Way more than enough presure from standard household water presure, in fact if you use fittings and there's no outlet you can make even small square or rectangular tanks made from 1/8 inch steel aproximate a sphere! Been there, done that! If you want to go to that sort of trouble, use a fitting to a hose that exits the tank and just put your thumb over it. The hose will get the overflow away from the tank so you can see any weepage. But if there is question about a tank for gas, if it leaks when just filled, time for a new tank!

[thinwater]

Originally Posted by ConradG

I think he was talking about removing the gas tank to tighten a fitting and see if there are any leaks. Although some of us won't even drive cars that burn gas, those that do don't worry about filling tanks, they just do. If you see no evidence of a leak other than the loose fitting, I wouldn't think twice about just filling it (out of the boat and outside) to see if there are any leaks.
I would caution against pressurizing any tank that has any gas or fumes in it. Static elec from plastic, fiber hose and you have a bomb! When I have made tanks, I have pressure tested them, but with water. Way more than enough pressure from standard household water pressure, in fact if you use fittings and there's no outlet you can make even small square or rectangular tanks made from 1/8 inch steel approximate a sphere! Been there, done that! If you want to go to that sort of trouble, use a fitting to a hose that exits the tank and just put your thumb over it. The hose will get the overflow away from the tank so you can see any weepage. But if there is question about a tank for gas, if it leaks when just filled, time for a new tank!

Do not pressurize in any way to over 5psi; tanks are not rated for that.

Do not pressurize with compressed air; I investigated a near-fatal caused by that. It increases the oxygen concentration - no, the nitrogen does not off-set that effect. You will get away with it 99% of the time....

Don't even think of pumping the gasoline out with any common electric pump. I've seen bad accidents with shop vacs. Use a manual pump rated for the product.

Teflon gas pipe tape (yellow) also works well. It is thicker and softer.

Filling with gas or diesel is fine. Clean the outside well so that you can see the seeps.

If there is any significant corrosion, there is no way to inspect the tank with any certainty without being able to see the inside well. Pitting attack is not that predictable.

I have gasoline on my boat, but it is a cat and the tank and engines are in bulkheaded compartments between the hulls that drain downwards.

[ConradG]

Good advice Thinwater!
I know plenty of people use gas engines and didn't mean to start any debate about the hazards. As I said in my first post, that's another kettle of fish.
However, it is very important to be sensible with such stuff!
I've built many tanks (for diesel and grease) and I do check with light water pressure as dicribed above because I am checking my welds.
With a gas tank there souldn't be doubt enough about it's condition to warrent checking it's integrity with presure. If there is, get a new (and approved) tank!

[sailvayu]

Best way to test with water is to fill the tank and have a stand pipe 3 feet above the top of the tank. fill to the top of the stand pipe and wait 24 hours. use antifreeze in the water if freezing will be a problem and you cannot do it in side. Adding die to the water can help find leaks from condensation. mark the water level and check for a drop. If you use air pressurize with 3 PSI and wait at least 1 hour and check pressure. Like the others say do not go over 5 PSI but 3 is standard for testing.

Good luck

[hugosalt]

Got it, 3psi /max. 5psi. You guys are great!

[Captin_Kirk]

Thanks guys. I pulled the tank, checked for leak and found none. I did clean it up and paint with a good paint. I took also found that the gas level sending unit was not working, so I am replacing that while it is out.