QUOTE(914werke @ Sep 22 2021, 12:27 PM)
QUOTE(jcd914 @ Sep 21 2021, 04:59 PM)
Not advise I would take. They are almost 50 year old plastic not designed to hold the pressure of the Fuel Injection system, just the weight of the fuel in the tank.
Again .. MISINFORMATION!
Ill agree tunnel lines can leak in stock form, but the incidence is (very) low and usually the causal reason is more likely abrasion from PO tinkering than simple pressure.
While its true early cars (70-74) were equipped with tunnel lines that were not designed /spec'ed for the hi-pressure use of the OE FI pump relocated to the front,
I continue to see cars that had been converted like this & have been running & driving for decades.
The late cars 75-76 have PLASTIC (Nylon?) lines
that ARE rated for high pressure.
My own experience from breaking
many many cars is that the tunnel lines are usually quite pliable and are likley to continue to perform as designed, in most cases.
But use common sense & don't succumb to Internet FUD!
All these cars are nearly 50 years old & its doubtful that Hans & Wolfgang engineers spec'ed these components to last this long.
Add into the mix they carry fuel formulations that are significantly different from the 1970's ... IMO its not a bad idea to replace those lines (in particular early) but to bang the gong that "your all gonna die" unless replaced is irresponsible.
More importantly, if still equipped with OE lines check them at the exit of the firewall in the Eng. compartment.
This where they are exposed to EXTREME HEAT and can degrade crack & cause fires.
Fire away
I would agree with 95% of what you say here.
the lines in the tunnel i pulled out 2 years ago (74 model) were still pliable and in first class condition. external to the firewall were brittle and would break by just bending them. the brittle area extended maybe 6 inches or so back into the tunnel beyond the engine bay firewall.
i doubt anyone in vw or porsche believed the cars would still be on the road in the numbers they still are at this point in time.
i'd love to know what the material and who the manufacturer of those fuel lines was.
the germans are/were incredible formulators of synthetic materials.
i don't believe those fuel lines at that quality are available anymore, anywhere.
i think they used plastic with a view towards collision protection.
the only thing that concerns me about stainless steel is it is brittle.
but i guess any accident where the fuel lines have to survive being bent in the tunnel is going to be one a human will find hard to survive?
re vapor lock problem with cars with rear fuel pump.
the problem is the magnesium fan shroud.
on shutdown it is a heat sink for all engine heat.
it gets very hot.
radiates at the fuel lines as well as the fuel pump.
the problem was a combination of the exposed fuel line which was only gravity fed as much as the fuel pump. with the pump in the front that exposed bit of fuel line along the rear firewall could be pressurised to overcome the vaporisation problem.
i'm leaving my pump in original location and heat shielding the fuel lines.
i never had a vaporisation problem with my original fuel pump.
but i do have one now with a modern in line pump in the original location.
i think the modern pumps are even more vulnerable to the vapor problem than the original roller cell pumps.