Steel fuel line repair - brass or plastic?

[Conor]

Afternoon all,

In the process of putting back the brazed fuel line into my SL. I need to join where I cut the pipe off, and these are my current options.

The plastic has been recommended to me by a seasoned mechanic but for me the brass (metal) fittings seems like a more solid solution... i'm just worried about galvanic corrosion.

Pipe will be under the floorpan of the car but covered by a plastic panel.

What do people think - what would you use?

 

[Chrishazle]

Cunifer not brass for the line.

 

[Doug1234]

The plastic fitting probably has an o ring each end that will eventually go hard or perish and eventually cause issues , so the brass one is best.

 

[Blobcat]

Cunifer not brass for the line.

That's a bit harsh...

I'd use kunifer...

 

[Conor]

Thanks all..

What's this kunifer you speak off... copper/nickel, eh!?

You will get straight up galvanic corrosion between copper and steel, right? Does the nickel counteract that?

Why not brass, will it weather badly and or corrode against the steel too?

I agree on the plastic connection.. I don't like the idea of plastic fittings for anything like this.

EDIT: Please post a link to a kunifer fitting as I can't seem to find anything.

 

[EmilysDad]

Afternoon all,

In the process of putting back the brazed fuel line into my SL. I need to join where I cut the pipe off, and these are my current options.

The plastic has been recommended to me by a seasoned mechanic but for me the brass (metal) fittings seems like a more solid solution... i'm just worried about galvanic corrosion.

Pipe will be under the floorpan of the car but covered by a plastic panel.

What do people think - what would you use?

View attachment 89232

the plastic fitting is an airline fitting. It'd probably work ..... but .... for how long? I'd use the solid brass fitting

 

[KennyN]

That plastic fitting is a Festo (?) air connection designed to work with Festo (?) plastic air lines and i certainly would not be putting fuel through it as there is no way of knowing how the internals will react to petrol or at how much pressure it will fail , plus the pipes would need to be a perfect size to get the internal locking mechanism to grip onto the original pipework.

Cant see why a mechanic would advise a push on air fitting on an part of a fuel system

These push on fittings are available in stainless , even then i wouldn`t recommend them on the fuel system.

They may work as a temp fix until it doesn`t.

If it were me i would get stainless or hydraulic compression fittings (for the longevity not the pressure) , which brings their own issue regarding the section of the pipework being able to cope with the olives that would be compressed onto them.

K

 

[Chrishazle]

Cu - copper - Ni - Nickel - Fer - well, Fe is iron so presumably that's how the name came about. It's what was used recently to re-do the brake lines on our S204 which had rotted out across the back axle both sides, don't know what connector he used to connect to the old steel line where he cut it. He did comment that it was awkward stuff to bend!

 

[Conor]

Cu - copper - Ni - Nickel - Fer - well, Fe is iron so presumably that's how the name came about. It's what was used recently to re-do the brake lines on our S204 which had rotted out across the back axle both sides, don't know what connector he used to connect to the old steel line where he cut it. He did comment that it was awkward stuff to bend!

Oh yes.. sorry I was in jest earlier. I know what it is for brakes as a proper alternative to copper.

But I haven't come across it in fittings.

Regarding that plastic quick fitting.. that one actually came out of a pierburg repair kit.. and after some research it seems they are suitable for liquid.

Google Pierburg fuel line repair kit and you will see what I mean.

I still like the idea of the brass though..I'd just be afraid it might corrode up against the steel will it?

 

[supernoodle]

There's an awful of rubbish out there, lots of dodgy sellers offering compression fittings for repair, which area not suitable.

This place does proper fittings in kunifer and steel.

Security measure

www.ebay.co.uk

 

[Conor]

There's an awful of rubbish out there, lots of dodgy sellers offering compression fittings for repair, which area not suitable.

This place does proper fittings in kunifer and steel.

Security measure

www.ebay.co.uk

I agree... but I believe Pierburg is an authority on fuel systems, no? Which is why I was even willing to entertain those push fittings.

Before today I had only ever seen them for air myself.

 

[Conor]

For clarification these fuel lines are 8mm..

 

[supernoodle]

Push fittings are ok if the pipe is the correct diameter and uniform surface. Not sure I would trust an old steel line is either of these.

 

[davidsl500]

Stainless steel braided fuel hose and clips?

 

[Conor]

Stainless steel braided fuel hose and clips?

Not in this instance unfortunately, there are a number of kinks and bends..

I really don't see what is wrong with the brass fittings, I think I am going to go with them.

A nut and olive compression kit is good for 200 BAR in the ABC system. I think the 4 bar fuel system will be safe.

I guess the query is around galvanic corrosion..

 

[EmilysDad]

...... and after some research it seems they are suitable for liquid.

,....

I use them at home connected to a water supply to automatically water hanging baskets

 

[Blobcat]

I use them at home connected to a water supply to automatically water hanging baskets

Handy when you've a supply of instrument air fittings and pipework...

 

[EmilysDad]

Handy when you've a supply of instrument air fittings and pipework...

stores stock

 

[davidsl500]

I had a quick thought: for galvanic action to take place, certain conditions need to be met : electrical connection between metals for instance but, the fluid moving through the pipe must be aqueous. Petrol is not aqueous therefore no galvanic action will take place..

 

[KennyN]

Google Pierburg fuel line repair kit and you will see what I mean.

When looking at the above repair kit it looks like the push on fittings are for the hard plastic pipe ,the rubber pipe take the internal ribbed fittings secured with jubilee clamps.

Also the max pressure is 5bar in ideal applications (80%) of what you have in the system.

We use these push on fittings daily at work and they "bite" into the outer diameter of the plastic pipe which is something that they wont do properly on a metal pipe so opting for the compression fittings the sensible option.

K