Fuel Line Sizing

I have looked for this info. Sorry if there is a thread here that I missed. However, I would rather get flamed here than have my car go up in smoke.
The fuel hose that exits the bottom of my fuel filter sprang a leak. It is old, cracked and ready for replacement. Can anyone tell me what size line is used (see photo)? And, while I am in there, I am going to just replace all the lines as they all look to be well past their service life. Is there a resource for finding the specs for all the lines? Pelican seems to sell a million different lines and I don't know what to choose. Thanks for the help!

10mm or 5/16" I would replace all of your flex / rubber or cloth covered lines, also in your pic top cloth line, that is the type of clamp you want to have, skip the screw clamp above what you are pointing at. As for lines, the cloth covered is very cool BUT does not hold up to methonal, Gates rubber has a fuel hose "Barrier" (I think) that is much more impervious to the methonal crap degrading fuel lines. my Napa carries it. Go front to back and do them all.

Regards
Edit: 8mm or 5/16"

Thanks Jerry. I am assuming that 10mm is the outside diameter?

Maybe I should clarify. This is a 1972 911e with MFI.

I’d also replace those hose clamps with a stainless ABA or an EFI clamp

You can buy most of the setup from the tunnel/pump/filter pre made and properly crimped and all, not as cheap as hose and clamps but.....

Quote:

---

Originally Posted by Jerry L

10mm or 5/16" I would replace all of your flex / rubber or cloth covered lines, also in your pic top cloth line, that is the type of clamp you want to have, skip the screw clamp above what you are pointing at. As for lines, the cloth covered is very cool BUT does not hold up to methonal, Gates rubber has a fuel hose "Barrier" (I think) that is much more impervious to the methonal crap degrading fuel lines. my Napa carries it. Go front to back and do them all.

Regards

---

Jerry- Just spent some more time looking at this. What I have seen at the Porsche site https://www.porsche.com/all/media/pd...73_KATALOG.pdf
is that those hoses have a part number of 999 180 030 50 and it is specified as being 7x12mm. I am assuming that 7x12mm refers to the inside and outside dimensions of the hose?

Not trying to be a pain in the ass. Just want to clarify. Is a higher quality hose of 10mm a suitable replacement for the 7x12 mm? I think maybe I am hung up a bit on the inside diameter of the hose, 'cause I don't want those suckers coming off! Thanks again for the help. I have a long standing habit of doing all my work 3 times. I would like to break that habit.

Sorry for my super huge font. I am not shouting.

If you try to replace a hose which has a 7mm ID with a 10mm ID hose it is almost certainly going to leak and if you try to tighten it enough to seal you will probably damage the hose.

It is good practice to use a hose that is around 0.5mm smaller diameter than the 'barb' as this makes sealing easier and means you only need minimal clamping force to retain the hose.

Quote:

---

Originally Posted by Jerry L

10mm or 5/16"

---

I'm stumped.

??

See this thread:
http://www.early911sregistry.org/for...ber-fuel-lines

Bryce,
I read it.

Call me slow witted but still not understanding the comment
10mm or 5/16”.

Bryce and Frank- Thanks for weighing in and for leading me to the other thread. I am ordering up the smooth Cohline lines in the appropriate size (7.3) and the porsche line in 9mm. I will also order some clamps. Appreciate all the help.

Sorry Frank, meant 8mm or 5/16" hose, basically the same fit in rubber hose depending what is available.

Regards

Quote:

---

Originally Posted by Frank Beck

Bryce,
I read it.

Call me slow witted but still not understanding the comment
10mm or 5/16”.

---

Quote:

---

Originally Posted by Jerry L

Sorry Frank, meant 8mm or 5/16" hose, basically the same fit in rubber hose depending what is available.

Regards

---

No worries. Anymore I assume I'm the one who is confused.

There are a great many threads on Pelican. Here is one, with input from our departed friends Grady Clay and Warren Hall: http://forums.pelicanparts.com/porsc...72t-mfi-2.html

Use Cohline hose, the original manufacturer, in original metric sizes, not inch hose from anyone else.

We have had very poor results with Cohline 2122 and Ethanol containing fuels and tried to resolve the problems we had over a period of 2-3 years.

https://imagizer.imageshack.com/v2/xq90/923/MRfWBE.jpg

https://imagizer.imageshack.com/v2/xq90/923/VaTx5h.jpg

It started to weep and leak after around 8 months with the car developing a very strong smell of fuel whilst garaged. Cohline advised that the engine bay temperatures in a 911 were probably greater then the 50degC rating of this hose and considered our concerns to be invalid. This hose pictured below was 8 months old and the car had been driven for about 50 miles during this time.

We also fitted Cohline 2122 to a 1967 'S' used in France with E85 fuel and the hose lasted 3 months before it failed.

We now use a hose manufactured in Denmark - Brand Name Codan 3106 - and this has been good for the last two years

Googled Codan 3106 and looks good, but noticed "Must not be used in cars with injection systems". Hmmm...thoughts?
https://www2.codan.com/node/28212

I am sure that this is more concerned with K Jetronic or EFI Systems which run much higher pressure than an MFI.

An MFI runs between 1 and 2 bar and the Codan is rated at 13 bar max. operating pressure and 50 bar burst pressure.

Cohline 2122 is typically rated at max. operating pressure of 7 bar and burst pressure of 30 bar.

Quote:

---

Originally Posted by chris_seven

We have had very poor results with Cohline 2122 and Ethanol containing fuels and tried to resolve the problems we had over a period of 2-3 years.


It started to weep and leak after around 8 months with the car developing a very strong smell of fuel whilst garaged. Cohline advised that the engine bay temperatures in a 911 were probably greater then the 50degC rating of this hose and considered our concerns to be invalid. This hose pictured below was 8 months old and the car had been driven for about 50 miles during this time.

We also fitted Cohline 2122 to a 1967 'S' used in France with E85 fuel and the hose lasted 3 months before it failed.

We now use a hose manufactured in Denmark - Brand Name Codan 3106 - and this has been good for the last two years

---

Chris, of course 2122 is only good for up to 10% ethanol. E85 would most certainly go right through it.

this looks like a suitable alternative.

http://www.volksbolts.com/FuelHose/index.htm

The point I was making was that in our experience Cohline 2122 is NOT compatible with E10 fuel when used in the engine bay of a 911 and I am aware of the difference between E10 and E85.

The hose shown on the above photographs is from a car used in the UK where the vast majority of fuel is still E5 - particularly premium grades which are 97 RON or above.

E10 will not generally be introduced into the UK until 2020 and is some of the reason why we have been dissapointed with the performance of Cohline 2122.

A fuel hose with a Max. Operating temperature of 50degC also seems too low for use in the engine bay of a 911 and Cohline stated this fact very clearly when we supplied them with samples of the failed hose from a UK based car.

The E85 fuel used by the car we service annually, which lives in France, suffered a catastrophic failure rather then just an issue with percolation and subsequent deterioration. We had advised our client not to use E85 and fortunately he has followed this strategy since the failure.

When we first encountered the problem we started changing fuel lines every year but this approach was less than successful and cars started to exhibit some issues after 6-8 months.

We then bought samples of 4 x different hose and kept it filled with fuel for more than a year.


Our first choice was Aeroquip Startlite 100 Series which is advertised an being compatible with E85 fuel and has a Black Nylon braid. It has a maximum operating temperature of 149 degC. It suvived a 12 month test without any sign of a problem.

There are however, two issues. The first is cost at around $40 per metre, the second is the ID, which at 8.6mm, -06) makes it difficult to seal onto an 8mm hose barb. If I would buy this hose in 7.5mm ID I would use it without hesitation.

We tested Codan 3106 and again results were good with no issues. The Codan is around 2 x the cost of Cohline and is quite difficult to source in the UK.

We tested Gates 4324 Series which was also sound but again is only available in -Dash sizes.

The control was Cohline 2122 which was, in our view, unsatisfactory with the braid becoming damp to the touch after about 6 months.

Cohline did comment that the hose sample we supplied only exhibited external cracking and that the inside diameter was reasonably sound and this was due to temperature effects and that we had used the hose outside it's design limits.

This clearly means that 2122 is unsuitable for use on a 911 as we only fitted this hose on SWB carburetted cars, with the hose fitted in the standard location. I find it confusing that 2122 was used for many years at engine bay temperatures in a 911 which have now become too high.

I am not surprised that the damage that is evident is concentrated to the outside of the hose as the manner in which the braid is applied does not help.

There is a good report issued by Transport Research Laboratory (TRL) in the UK where they clearly demonstrate that Ethanol increases the 'mass transport' of gasolene through an NBR hose and the escaping vapours wash out the synthetic binders from the rubber and that this causes embrittlement and cracking.

The type of binders being used has a significant impact on the behaviour of individual hoses and I found Cohline's explanation regarding temperature unconvincing.

Clearly to form a quantifiable conclusion would need much more work than we have carried out but we simply decided not to take the risk and use Codan.

The Gates hose I mentioned is 4219 BG "Baricade" Green Shield, rated to 3.5 bar / 50 psi, will enquire on MM sizing. made for ethanol resistance.

Regards

The Gates 4219 is a very good hose but we didn't try it out as it doesn't have a textile 'overbraid' and we specifically wanted hose that maintained the original appearance if that were possible and we limited our search to hoses of 'original' appearance.

4219 is available with a 5/16" ID which is 7.9mm and an OD of just over 14mm so is lightly larger than the original.

There are also Cohline and Codan hoses that may be good that aren't braided and they are also slightly larger in outside diameter.

Thanks Chris, I will try to source the braded cover version you posted, went to the rubber version after quick failure of the fabric covered from Stoddard & others failed too quickly. Appreciate the information.

Best Regards

I have 50metres of the Codan in 7.5mm dia if I can help.

Any thoughts on Continental? Same as Cohline? for example:
https://www.ebay.com/itm/BMW-7mm-Clo...9UxUkl&vxp=mtr

Thanks Chris, was able to order a roll of the 8mm 4324 -10053, fabric covered. Will now have it on hand, Sterling, Peter, feel free to stop by if you want some, I will be here by the time I get back from the Texas Hill Country Rally.

Thanks again for the information and your research!!