Copper fuel line leaking fitting - not a typical flare fitting

[BDale]

Hello, looking for some advice.
I have a thin copper fuel (gasoline) line running almost to the engine. The the copper marries to rubber fuel line just before the filters via some sort of compression fitting although it is not the typical flare fitting I’ve seen on other posts. It leaks slightly. When the two sides of the fitting are completely tightened together the whole fitting can still spin fairly easily on the copper line. Can someone name this type of fitting and offer a possible solution. Thank you!!

[motion30]

I much prefer a flare fitting on A-line that carries fuel. But if you do not have the tools for that,remove that mess cut that copper back a 1/2 an inch and go to the hardware store and get a proper compression fitting mated it to a barbed fitting in the appropriate size for your hose

[Uncle Bob]

Originally Posted by BDale

Hello, looking for some advice.
I have a thin copper fuel (gasoline) line running almost to the engine. The the copper marries to rubber fuel line just before the filters via some sort of compression fitting although it is not the typical flare fitting I’ve seen on other posts. It leaks slightly. When the two sides of the fitting are completely tightened together the whole fitting can still spin fairly easily on the copper line. Can someone name this type of fitting and offer a possible solution. Thank you!!

It's a brass olive, is it the correct size for the tubing and is the fitting one that is designed for the purpose. In my experience the nut does not normally tighten all the way down, it almost does but not all the way.

[BDale]

I assume it’s the correct size. Pretty sure it’s the original line on a 50 yr old boat. Yes it seems like it should be snug before the two sides meet

[Searles]

Be aware the brass olive is a once only use fitting,the copper tube may also be compressed ,bust answer is to start again ,get flair fittings if possible.⛵️⚓️

[Jammer]

Originally Posted by BDale

Hello, looking for some advice.
I have a thin copper fuel (gasoline) line running almost to the engine. The the copper marries to rubber fuel line just before the filters via some sort of compression fitting although it is not the typical flare fitting I’ve seen on other posts. It leaks slightly. When the two sides of the fitting are completely tightened together the whole fitting can still spin fairly easily on the copper line. Can someone name this type of fitting and offer a possible solution. Thank you!!

It's a compression fitting, and once it's been overtightened (which is easy to do), you have replace the ferrule (ring, olive, etc.) and cut off the last 3/8" of the line where the old ferrule was, and reassemble it.


Or you can replace it with a flare fitting, which are generally more reliable and less susceptible to overtightening, but then you'll need a new fitting and a flare tool.

[Bowdrie]

Compression fittings with gasoline give me the "heebie-jeebies".
A proper flare is better.
For best security/peace of mind, don't use the thin-wall machined brass flare nuts, (garden variety hardware store).
Go to a refrigeration supply house, get forged brass flare nuts, they don't deform under wrench torque/pressure.

[BDale]

Thanks for the responses. Bought flare tool and fittings. I’ll let yo know how it turns out.

[Jammer]

ok so there are some things you should know


First of all for gasoline, on the threaded portion of the fitting (not the part where the flare not will go, the part that is being screwed into that coupler) you will need to use a good clay-based thread dope to get the threads to stay sealed. I would suggest Rectorseal #7 if you can get it. I would not recommend tape. It may be helpful to chase the threads with a tap and die before applying sealant. These are inexpensive and readily available in the small sizes used for fuel lines.


On the flare itself there are two common mistakes. The first is that it is easy to get a fold in the flare from the burr where the tubing has been cut. It is vital to "flip" the burr so that the flaring tool pushes it outside the tubing rather than folding it to the inside. Just roll it out with a straight, round object like the round part of a screwdriver shaft near the handle, or the handle of the flare tool. It doesn't take much force. Look at the completed flare, if there's a fold in it, it won't seal properly and you'll have to start over.


The other common mistake is that you should lubricate the flare nut with oil prior to tightening it. You want to get enough force on the flare itself to form the metal-to-metal seal and the oil helps with that. Don't use pipe dope on those threads.

[BDale]

Originally Posted by Jammer

ok so there are some things you should know


First of all for gasoline, on the threaded portion of the fitting (not the part where the flare not will go, the part that is being screwed into that coupler) you will need to use a good clay-based thread dope to get the threads to stay sealed. I would suggest Rectorseal #7 if you can get it. I would not recommend tape. It may be helpful to chase the threads with a tap and die before applying sealant. These are inexpensive and readily available in the small sizes used for fuel lines.


On the flare itself there are two common mistakes. The first is that it is easy to get a fold in the flare from the burr where the tubing has been cut. It is vital to "flip" the burr so that the flaring tool pushes it outside the tubing rather than folding it to the inside. Just roll it out with a straight, round object like the round part of a screwdriver shaft near the handle, or the handle of the flare tool. It doesn't take much force. Look at the completed flare, if there's a fold in it, it won't seal properly and you'll have to start over.


The other common mistake is that you should lubricate the flare nut with oil prior to tightening it. You want to get enough force on the flare itself to form the metal-to-metal seal and the oil helps with that. Don't use pipe dope on those threads.

I’m confused. Do they not thread to each other? Oil on one side and thread dope on the other??

[maine-cruiser]

I think what Jammer is saying is this. Reference your first picture, where the copper tubing goes into the compression fitting (now a flare fitting) you use some oil. On the other end of that adapter you have male threads that go into an adapter and thence to the rubber hose to the engine. Use pipe dope on those male threads.

Bill

[Jammer]

What Bill said.

[BDale]

Originally Posted by maine-cruiser

I think what Jammer is saying is this. Reference your first picture, where the copper tubing goes into the compression fitting (now a flare fitting) you use some oil. On the other end of that adapter you have male threads that go into an adapter and thence to the rubber hose to the engine. Use pipe dope on those male threads.

Bill

Ok gotcha! Dope won’t be necessary then as I found a flare fitting with the hose end on it?

[Jammer]

Correct. That's a reverse double flare, they work great too.

[Bowdrie]

An Inverted flare.
Most commonly used with double-flare steel hydraulic brake lines.