Working with polyamide tube.

Replacing fuel lines on old VWs seems to be one of those popular things to do at the moment.
The composition of our fuel has changed and we keep hearing all those horror stories on forums about vans going up in smoke due to perished fuel lines.
The thing is, it’s usually only the end rubber sections that fail however what usually happens is that some do-gooder has gone and replaced the lot with rubber, front to rear! It’s a common situation and why we have started manufacturing replacement fuel feed and return pipes to be sold as a complete item and to put the van back to how it should be.
The hard plastic fuel lines are made from a material called “Polyamide” and are very robust, not only chemically but they also resist abrasion very well if clipped into place as they should be.
The polyamide tube we sell is manufactured to DIN 73378.
Polyamide tube is really easy to work with so we thought we would put a quick page together to help you understand some of the products a little better and to give a little more confidence in working with this robust, durable and cost effective fuel line.

Oetiker clip closing pliers.
A selection of Oetiker clip closing tools, all work well. Left: Genuine Oetiker closing pliers. Middle: Common or garden pincers and… Right: Professional closing pliers.
Genuine Oetiker closing pliers.
Genuine Oetiker clip closing pliers, nice and sharp and produce an attractive crimp.
Workshop tool.
The tool we use in the workshop, it has an extra heel to keep the ear of the clamp bulging too far, great for CV boot clips.
Pre-mating.. foreplay if you must
To the left, 8mm OD polyamide tube, the brass section in the middle is a reinforcing sleeve and to the right our 7.3mm FPM fuel hose.
Sleeve meets tube
Easy bit, push the reinforcing sleeve into the end of the polyamide tube all the way up, as far as it goes. The sleeve is there to stop the polyamide tube getting crushed when hose is clamped over the top.
Rocket science
The, over goes the FPM, easy huh. push the hose over the poly tube by about 15mm, about the same length as the reinforcing sleeve.
Centring the clip
Centre the clip over the reinforcing sleeve.
Crimp.
Over goes the Oetiker clip, these are stainless steel so perfect for use underneath the van.
Hug me, squeeze me, hold me tight.
The Oetiker clip is clamped up to leave a 1mm or so gap between the 2 opposing bits of the clamp.
I can see right through you..
Here you can see there is still an air gap in the ear of the clamp. 1mm or so is what you are aiming for.
Polyamide
Here is a poor representaion of the cross section of a completed joint. Black: Polyamide tube, Grey: Fuel hose, Yellow: Reinforcing sleeve, Blue: Oetiker clip

When it comes to sizes you need quite a tight fit, for a 8mm tail such as the output from a fuel tank you need 7,3mm fuel hose, the same goes for 8mm OD polyamide, 7,3mm ID fuel hose.

For 6mm tails or polyamide tube you use 5.5mm ID hose.

Polyamide tube and reinforcing sleeves can be found here

Decent quality fuel hose can be found in this section. [look for the FPM]

Oetiker clips can be found here. The correct sizes are in related products on the hose pages though.

Closing tool for Oetiker and CV boots but you can use normal pincers.

Or, if you want to buy it already done then we have a couple of kits already made.

2.0l AC “CU” engine fuel feed kit.

1.9l WBX “DG” Engine fuel feed kit.

To fasten the pipes down the length of the chassis…

Omega clip

The change hose size.

8mm to 6mm reducer

12mm to 8mm reducer

For making removable connections to the fuel tank, filters etc..

For 5.5mm hose / 6mm tail

For 7.3mm hose / 8mm tail

Hopefully that should give you a little insight into this great product and help you save some money by not ditching the PA and swapping the lot for rubber!