[DrewPT]

When I was cutting the engine bay hoses on a 1990 donor sedan for the better-condition fittings, I noticed there was no threading woven through it--rather it looks like two layers. And, since this was connected on one end to the hard line at the firewall, it must have been original (no clamps were on it, it's swaged). How on earth would a fuel hose last this long, especially on a California car (SF area) where they probably had ethanol and even a little lower octane than what we've had in the rest of the country? It also says on the hose, Contitech 8x3 1 90, whatever that means (I was looking for 8.5x13.5 or 8.4x13.5).

On the Belmetric site, there is a page of hoses that look like this but since I wasn't familiar with them, I ordered the threaded version that I'm familiar with. Would this type be a better option for longer-term, and higher safety?

 

[Kingorcus]

When I was cutting the engine bay hoses on a 1990 donor sedan for the better-condition fittings, I noticed there was no threading woven through it--rather it looks like two layers. And, since this was connected on one end to the hard line at the firewall, it must have been original (no clamps were on it, it's swaged). How on earth would a fuel hose last this long, especially on a California car (SF area) where they probably had ethanol and even a little lower octane than what we've had in the rest of the country? It also says on the hose, Contitech 8x3 1 90, whatever that means (I was looking for 8.5x13.5 or 8.4x13.5). View attachment 2810418 View attachment 2810419

On the Belmetric site, there is a page of hoses that look like this but since I wasn't familiar with them, I ordered the threaded version that I'm familiar with. Would this type be a better option for longer-term, and higher safety?

The best thing to do is to get original parts, however they are NLA.

or

M8X14 Rubber Insulated - Polyamid Hard Plastic RHPOLY8X14 / 3124 0800

is the Polyamid which require no clamps.

There are three lines, high pressure coming from tank to FD, lower pressure from FD to AC, lower pressure from AC back to tank.

some members also used fuel injector lines with clamps with success...

The hard part is to remove the existing lines off the metal.
I think if you are going to use the Polyamid with no clamps you might have to remove the metal line as well as sliding the rubber over metal requires some force, not sure if you can do this with lines in the car.

This is on my list of things to do eventually, however my lines look good....

P.S. I would buy a small piece of the rubber hose and do the small connection between the FD and AC first to see how it works.. By the way that one piece is still available from MB but not the other two....

 

[John350]

it looks like two layers.

The inner liner is specificly chosen for resistance to fuel components (as of 1990). The outer layer is for abrasion, heat, oil, etc. resistance.

It also says on the hose, Contitech 8x3 1 90, whatever that means

I'll bet it means made by Contitech, 8mm ID, 3mm wall, in January of 1990.

Would this type be a better option for longer-term, and higher safety?

Newer spec hoses are more likely to withstand newer spec fuels. SAE J30R9 is the most recent spec for fuel injection hoses.

 

[DrewPT]

The best thing to do is to get original parts, however they are NLA.

or

M8X14 Rubber Insulated - Polyamid Hard Plastic RHPOLY8X14 / 3124 0800

is the Polyamid which require no clamps.

There are three lines, high pressure coming from tank to FD, lower pressure from FD to AC, lower pressure from AC back to tank.

some members also used fuel injector lines with clamps with success...

The hard part is to remove the existing lines off the metal.
I think if you are going to use the Polyamid with no clamps you might have to remove the metal line as well as sliding the rubber over metal requires some force, not sure if you can do this with lines in the car.

This is on my list of things to do eventually, however my lines look good....

P.S. I would buy a small piece of the rubber hose and do the small connection between the FD and AC first to see how it works.. By the way that one piece is still available from MB but not the other two....

Is this polyamid hose the same type of thing that is in the attached photos? I did order the one last available engine bay hose MB still makes. I also ordered replacement hoses (230 prefix number) where called for, and it's the threaded type, not polyamid. Any guarantee of greater longevity and safety with one or the other?

 

[Kingorcus]

Is this polyamid hose the same type of thing that is in the attached photos? I did order the one last available engine bay hose MB still makes. I also ordered replacement hoses (230 prefix number) where called for, and it's the threaded type, not polyamid. Any guarantee of greater longevity and safety with one or the other?

There are many threads on this topic.

I do not have a definite answer for which one is better...

One thing I do not like the design of what MB did, is that you have to remove the whole metal line to change the hose. They should have a screw fitting on both the firewall side and the other side, this way you can remove that piece without moving the whole metal line from under the wheel.
Bad design.

I believe that is not the case with the R107...

 

[DrewPT]

The best thing to do is to get original parts, however they are NLA.

or

M8X14 Rubber Insulated - Polyamid Hard Plastic RHPOLY8X14 / 3124 0800

is the Polyamid which require no clamps.

There are three lines, high pressure coming from tank to FD, lower pressure from FD to AC, lower pressure from AC back to tank.

some members also used fuel injector lines with clamps with success...

The hard part is to remove the existing lines off the metal.
I think if you are going to use the Polyamid with no clamps you might have to remove the metal line as well as sliding the rubber over metal requires some force, not sure if you can do this with lines in the car.

This is on my list of things to do eventually, however my lines look good....

P.S. I would buy a small piece of the rubber hose and do the small connection between the FD and AC first to see how it works.. By the way that one piece is still available from MB but not the other two....

I called Belmetric today, and he said for extra peace of mind with the high pressure/other mechanics seeing the polyamide hoses with no clamp, that I could use a 15.5mm ear clamp on the hose over the barb. Thing is, these clamps are 8.5mm wide and the barb convex thickness is not that wide. Since the polyamid hose molds to the barb better than the regular rubber hoses, would the ear clamp not cut into the concave portion?

 

[DrewPT]

The inner liner is specificly chosen for resistance to fuel components (as of 1990). The outer layer is for abrasion, heat, oil, etc. resistance.

I'll bet it means made by Contitech, 8mm ID, 3mm wall, in January of 1990.

Newer spec hoses are more likely to withstand newer spec fuels. SAE J30R9 is the most recent spec for fuel injection hoses.

The gentleman at Belmetric recommended the Choline 2240 series with blue font, apparently it's rated for the newer ethanol fuels and in case I found the polyamid hoses untenable to install. I will do my best to only use ethanol-free fuel, however, as long as I can get it.

 

[Kingorcus]

I called Belmetric today, and he said for extra peace of mind with the high pressure/other mechanics seeing the polyamide hoses with no clamp, that I could use a 15.5mm ear clamp on the hose over the barb. Thing is, these clamps are 8.5mm wide and the barb convex thickness is not that wide. Since the polyamid hose molds to the barb better than the regular rubber hoses, would the ear clamp not cut into the concave portion?

That is the question you should ask the experts at Belmetric.
All I know is that polyamide works without clamps for a reason..

 

[John350]

The cars I worked on in the '70s and '80s with K-Jetronic used the plastic hose with barbed fittings exclusively. I don't recall any rubber hoses in the whole system, although I could be mistaken. It made working on the system much easier than rigid metal lines!

(No clamps required. Line repairs were exactly as shown in the video in post #2)