Fuel leak L36

[Rob M.]

On my 1969 the fuel line between the fuel filter and the carburetor was no longer reliable and had to replaced. I ordered a new fuel line set from CC but not mounted it is leaking at the fuel filter fitting. Should there be some sort of O ring there or should it be fitter without some sort of gasket (metal on metal)?

[Edward B.]

Re: Fuel leak L36

No o-ring, just metal to metal Rob. And yes, they leak. You have to really tighten the crap out of the repops. If you got stainless, forget it. It'll ALWAYS leak. But if you got plain steel, then the trick I used was to tighten, loosen, tighten, loosen and keep repeating until no leaks. Sometimes it takes several cycles but eventually, the two parts (the filter and the line) will mate to each other.

Ed

[Michael H.]

Re: Fuel leak L36

You may want to look for Flair Savers as they are made out of thin copper and would go between both steel lines and seal. I've had great success using these.

Mike

[Rob M.]

Re: Fuel leak L36

You may want to look for Flair Savers as they are made out of thin copper and would go between both steel lines and seal. I've had great success using these.

Mike

I had to look up what a flare save is using Google. I wonder where I could get these little gizmos?

[Michael H.]

Re: Fuel leak L36

I had to look up what a flare save is using Google. I wonder where I could get these little gizmos?

Rob,

I bought mine years ago they are used in the Aerospace/Aircraft industry.

Mike

[John M.]

Re: Fuel leak L36

Rob,
You can get them from Grainger. Parker 45 deg. copper flare gaskets. They work nicely.

[Rob M.]

Re: Fuel leak L36

I'll see if I can buy a couple when I'm over in the States next week...

[Gary C.]

Re: Fuel leak L36

Rob, need to get you a tube of Fuel Save aircraft line sealant also.

[Steve G.]

Re: Fuel leak L36

Tighten the flair nut as tight as you you are able with still being able to turn the line in the flare nut. Twist the filter back and forth on the line a few times, then tighten the rest of the way.

The twisting under pressure of the soft metal mating surfaces causes them to conform to one another.

Steve

[Terry B.]

Re: Fuel leak L36

Unfortunately I over tighten my fuel line where it goes into the carb and had to take the carb to a machine shop to have the threads re- machined. There is a limit to the stress the fitting can take. Be sure everything is lined up correctly and do not over tighten. I hope the earlier given solutions work for you.

[Michael F.]

Re: Fuel leak L36

use that white pipe tape for sealing

[John H.]

Re: Fuel leak L36

use that white pipe tape for sealing

The white tape can shred while tightening the fitting and release crud to get in the needle-and-seats; I prefer using a light film of TFE pipe dope on the threads to reduce thread friction and reduce applied torque required to get the flare to seal (the threads don't seal anything).

[Joe L.]

Re: Fuel leak L36

Unfortunately I over tighten my fuel line where it goes into the carb and had to take the carb to a machine shop to have the threads re- machined. There is a limit to the stress the fitting can take. Be sure everything is lined up correctly and do not over tighten. I hope the earlier given solutions work for you.

Terry-------

When tightening the tubing nut, you MUST hold rigid the fitting nut which threads into the carburetor. Use an open end wrench for this. You were lucky that you only damaged the threads. You could have fractured the float bowl thereby ruining the carburetor.

[Steve G.]

Re: Fuel leak L36

Teflon tape or pipe dope of any kind does not belong on a straight thread fitting. As Joe said, anchoring the large nut when you tighten the smaller is critical.

But probably the biggest cause of damaged threads on that large nut and bowl, as well as other places where a gasket is used, is the failure to replace the gasket. It should be replaced every time it has been loosened.

The whole idea of a gasket is to compress and take the shape of the two surfaces the gasket is sealing. It does not decompress when you loosen it. So every time you re-tighten that nut the gasket has to try to compress further to achieve a seal. This takes more force the further you have to compress it. Eventually there is no compression left and you have to tighten it well beyond spec to achieve a seal.

Of course this leads to the smell of fuel when the car sits in the garage from the weeping at the nut so they wire back their heat risers and block the crossovers to stop the fuel from "percing".

Sorry, couldn't resist it

Steve

[Rob M.]

Re: Fuel leak L36

Teflon tape or pipe dope of any kind does not belong on a straight thread fitting. As Joe said, anchoring the large nut when you tighten the smaller is critical.

But probably the biggest cause of damaged threads on that large nut and bowl, as well as other places where a gasket is used, is the failure to replace the gasket. It should be replaced every time it has been loosened.

The whole idea of a gasket is to compress and take the shape of the two surfaces the gasket is sealing. It does not decompress when you loosen it. So every time you re-tighten that nut the gasket has to try to compress further to achieve a seal. This takes more force the further you have to compress it. Eventually there is no compression left and you have to tighten it well beyond spec to achieve a seal.

Of course this leads to the smell of fuel when the car sits in the garage from the weeping at the nut so they wire back their heat risers and block the crossovers to stop the fuel from "percing".

Sorry, couldn't resist it

Steve

Ok, but I understood that there is no seal...