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copper and petrol don't mix
MikeR - 18/4/22 at 02:01 PM

I've got a little fuel tank, I put some petrol in it about 2 years ago. I needed a pick up pipe so used a bit if 8mm copper heating pipe. Tank has a small 6mm vent.

Just drained the tank today. Not sure petrol should look like that or the pick up pipe. Was only every supposed to be temporary but it's surprised me.


What had gone wrong? (Was thinking of using 8mm pipe for the entire fuel system). Is it the fact it has a air vent?

(Picture to follow, in case the picture didn't work the petrol is green, the copper pipe has green corrosion)

green petrol
green petrol


[Edited on 18/4/22 by MikeR]


tegwin - 18/4/22 at 03:27 PM


BenB - 18/4/22 at 05:10 PM

Is it likely to be that new "green" petrol (quite literally). As far as I'm aware e5 and e10 don't play well with copper.


MikeR - 18/4/22 at 05:21 PM

This petrol was at least 2 years old so not E10 unfortunately.


Sanzomat - 18/4/22 at 05:46 PM

Would still have been E5 2 years ago. The bioethanol in E5 can react with all sorts of things. It is also hygroscopic so absorbs water from the atmosphere (if it can) and the water and dilutes the ethanol and separates out over time standing which I guess might also be reactive with copper.


bi22le - 18/4/22 at 06:34 PM

I have copper pipes for fuel lines and the car has stood for a fair while at times. I guess the pipes were not always in the fuel though so no long term exposure.

It would have been super, incase they makes a difference.

I guess where I be am going with my post is to not worry about copper pipe being used in the fuel system.


SteveWalker - 18/4/22 at 07:44 PM

My copper pick up pipe was covered in green muck and the zinc plated mild-steel sender unit was very badly rusted. Both now replaced with stainless steel. However, some of my piping remains copper and some is aluminium. So far they seem okay and the filter before the carb is not filling with crud.


robocog - 19/4/22 at 07:36 AM

Car sat for about 9 years
I have copper pipes as outlet and for fuel return from swirl pot
I emptied the "fuel" out whilst I was recommissioning it - plastic tank and from alloy swirl pot
It was not green (but stank really quite nasty and had a reddish tinge - rust?) and my sender had turned to rust to the point it snapped getting it out of the tank
The copper fittings in the tank didn't look that great, green tinge and some stuff growing on them, but am re-using them
I have just fitted a stainless fuel tank sender so hopefully fewer issues down the line

All rubber fuel lines were replaced as they had either gone rock hard and/or leaky
The hard plastic lines seem OK
The motorcycle lift pump to swirl pot took a bit of encouragement to get ticking and pumping
The Bosch 044 HP pump had completely died (and got replaced with a cheap after market job)
Had the car running, injectors and fuel reg seem to be OK (not had it under any real loads yet)
Got a rebuildable clear glass filter between tank and lift pump, and it has stayed clear so far, but then it has not seen any fuel sloshing yet and I am sure there will be the remains of the fuel sender in there still


Mr Whippy - 19/4/22 at 11:48 AM

tbh I don't think it should be a problem as really petrol more than 6 month old is past its best and should be changed out however 8mm brass tube is not actually very expensive and probably a better material. Although seeing that most manufactures are now using plastic I'd be quite happy with that too.


coyoteboy - 19/4/22 at 02:14 PM

Yeah everyone says that, but I ran a tank of 6 year old fuel through a GT4 and noticed no increase in knock and no misfires. Don't get me wrong, I'd not choose to use 6 year old fuel as the first tank on a multi-continent driving trip, but meh, people worry too much what petrol companies claim.

But petrol in copper pipes seems like a bad idea if it's left standing for any length of time, copper is very reactive and fuel does contain some water and other items that would oxidise the copper.


SJ - 20/4/22 at 01:52 PM

I've had copper on mine since 2006 with no noticeable issues.

Will have a check at some point though to see what things look like.


hughpinder - 20/4/22 at 02:31 PM

Here is something from a sailing boat perspective:

https://www.practical-sailor.com/boat-maintenance/are-copper-zinc-and-brass-mucking-up-our-fuel

And for classic cars:
https://www.hagerty.co.uk/press-release/why-new-e10-eco-fuel-could-damage-your-classic-car/

Probably best to buy plastic or kunifer pipe.

Regards
Hugh


Mr Whippy - 20/4/22 at 09:33 PM

quote:
Originally posted by coyoteboy
Yeah everyone says that, but I ran a tank of 6 year old fuel through a GT4 and noticed no increase in knock and no misfires. Don't get me wrong, I'd not choose to use 6 year old fuel as the first tank on a multi-continent driving trip, but meh, people worry too much what petrol companies claim.

But petrol in copper pipes seems like a bad idea if it's left standing for any length of time, copper is very reactive and fuel does contain some water and other items that would oxidise the copper.


I think it is very much down to how the petrol is stored. If it's in a full airtight container I doubt it would go off even after many years, maybe just needing a good shake. However in a half empty fuel tank the petrol seems to go a different colour and loose a lot of its smell, something you'd expect from such a volatile liquid. I've certainly had occasions where cars left for ages ran dreadful or failed their MOT and the only thing required was a fresh tank.

Quite funny is some of the Youtube car vids where they are trying to get some ancient vintage car to run again where the engine oil has turned to jello and the petrol to some sort of brown crust!


hughpinder - 21/4/22 at 07:40 AM

The degradation is of several types:
1. Loss of volatile part evaporates as Mr Whippy describes and will be fairly quick unless the fuel is stored in an airtight container.
2. Absorption of water, not an issue with traditional petrol, but the 5% or now 10% 'bio' is ethanol which will suck the water out of the air in no time. The water then reacts with the petrol part this is also quite quick - again easiest remedy is to store in an airtight container.
3. Petrol / Ethanol are organic compounds so degrade due to chemical reactions caused by sunlight, and different bits of the fuel reacting with each other and/or the air in the tank (petrol isn't a single compound...). This would be relatively slow.
4. Chemical reaction between the storage container/fuel lines and the fuel - so for example the sulphur in the fuel reacts with various metals etc etc, plastics may dissolve or partially dissolve in the petrol or ethanol or water in the fuel etc.....
5. Different parts of the fuel could stratify, so shake the can!
To get the ideal solution just consider all of the above.

Regards
Hugh


jester - 21/4/22 at 11:13 PM

Many years ago I used a fuel addative in my motorcycle as recommended by the Motorcycle dealer

to add to a running to motorbike before storing over winter to save the fuel lines & tank & the fuel left

Will have a look about in the next few days to find the old bottle in the garage for the make


MikeR - 22/4/22 at 12:52 PM

So if I don't want to use rubber tube all thorough the car, what hard line is available that isn't copper based?


hughpinder - 22/4/22 at 01:58 PM

kunifer/cunifer is probably your best bet/easy to get hold of


MikeR - 22/4/22 at 02:25 PM

But that's an alloy of /with copper (or have I misunderstood what it is)


robocog - 22/4/22 at 06:24 PM

I thought it stood for Cu (copper) Ni (nickel) Fe (iron)
Not sure what the 'r' at the end is...dash of pirate maybe?


indykid - 22/4/22 at 07:04 PM

quote:
Originally posted by MikeR
But that's an alloy of /with copper (or have I misunderstood what it is)


Stainless steel is an alloy of mostly iron but the chromium and other alloying elements stop it corroding (austenitic grades at least).

That's the magic of alloys.


perksy - 22/4/22 at 07:34 PM

quote:
Originally posted by jester
Many years ago I used a fuel addative in my motorcycle as recommended by the Motorcycle dealer

to add to a running to motorbike before storing over winter to save the fuel lines & tank & the fuel left

Will have a look about in the next few days to find the old bottle in the garage for the make




Sta-Bil Fuel Stabilizer ?