[T3] Fuel Hoses

[Jim Adney]

On 1 Feb 2013 at 14:01, J. Jonik wrote:

> Is it correct that there is some agreement that Rubber Fuel Hoses are
> better than the braided kind?   Or are both just as good? 

All fuel hose is braided, the US made style just has an extra layer 
of rubber over the outside, hiding the braiding. As you've noticed, 
this makes the US style hose larger on the OD.

For the past few years, however, the european style hose has seemed 
to be of poor quality. There's no excuse for this, but it seems to be 
the case, even when buying name brand hose.

> So, looking for some fuel hose to keep on hand, I found 5/16" rubber
> hose available at local Auto Parts store.   It fit a metal piece of
> fuel hose linkage (that I carried around for size) like a tight
> glove.    I didn't buy any yet. 

5/16" = 8 mm, so the size is right.

>  BUT...this hose was half again, or more, wider than the braided
> hose.  I think that would be a squeeze at a few places...like at the
> injectors, or threaded through the plate at the pump mount....or
> elsewhere?

There are 3 places where the larger size can be a problem: 2 at the 
fuel pump plate and 1 where the hose passes thru the engine breast 
plate. Everywhere else there's no problem. That OD size, however, is 
a problem that I've battled for a long time.

I now have hose that's labeled as 5/16" hose and has the same OD as 
the european style hose. Although the ID is actually a little smaller 
than 8 mm, it stretches nicely to fit our fittings and I've had very 
good service from it for quite a few years. I can sell it for $3 per 
foot or $60 for 22' to do an entire car. Shipping is extra.

I also stock the special pinch type hose clamps, similar to the OE 
ones used by VW. I use them in only certain places where they make a 
neater installation. I use standard worm gear hose clamps most 
places, or at least at one end of every hose (so everything can be 
disassembled without cutting a clamp.)

I should mention that the OE hose was actually 7 mm, but was replaced 
by 7.5 mm after VW found too many failures from stretching over their 
fittings. The US hose I now have does not seem to suffer in the same 
way. You can still find people on ebay selling the 7 mm stuff; don't 
buy it. The 8 mm hose doesn't seem to do any better.

You can also find special 5/16" fuel injection hose at your local 
FLAPS. It's a LOT more expensive and is intended for modern FI 
systems that run at much higher pressures than our cars. It will work 
for us, but so will the cheaper stuff.

One thing to watch when you're installing new hose is the bend 
radius. Don't expect your hose to tolerate whatever bend you subject 
it to. Install it with large smooth curves wherever possible. And 
don't overtighten the worm gear hose clamps; barely snug is almost 
always enough. There are only 2 connections on our cars that can be 
difficult to seal: the 2 ends of the steel tube that carries gas from 
the front to the rear on the left side. Those connections are hard to 
seal because the tube ends are not bulged; they are just straight.


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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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