RJ80

A few questions for the more technically inclined here. I've done several searches, but I can't seem to find answers for these fuel line questions.

As a precaution, I'm replacing what I assume are the original fuel lines on my 125k-mile '89 S2. I've purchased the Lindsay Racing kits for both the rail and the damper (two hoses per kit/four hoses total). In the engine bay, I can see that the fuel rail hoses terminate at hard lines located just above the wheel well. I also see the shorter damper lines at the front of the fuel rail.

These lines all seem to have a soft rubber exterior with what is clearly a harder interior component. Metal? I don't see any damage on the rail lines, but there is some cracking in the rubber exterior on one damper line. It seems like the rubber is just insulation? Is that correct?

What should I do to depressurize the system before replacing the lines? Is pulling the DME relay and cranking the engine a few revolutions enough?

Any tips to avoid catastrophe? Should I expect the old lines to give up a struggle when removing them? I assume that flare nut wrenches are a must.

Thanks!

plumbum

I haven't changes my S2 lines but did them on my 951. The exterior rubber covers the fuel line..if yours is cracking it's a good sign they needed replacement.

I cracked the lines and covered them with a rag to catch any pressurized fuel..there wasn't much. Flair wrenches are best to break the nuts free and after that a regular wrench will work.

Hope this helps

RJ80

Thanks for the advice. Why is it a big deal if exterior insulation is cracked if there's a metal fuel line in the center? Obviously, rubber is going to break down faster than metal. I'm not trying to be contrary, just trying to understand. If these were pure rubber lines (like flexible brake hoses) then it would make sense to me.

jhowell371

The inside of the lines have a Teflon liner. I replaced the ones on my S2 with lines I had made up and crimped locally. The fuel damper lines I made myself, they are just push on fittings. I slit the outside insulation, removed it and put it on my new lines with wire ties. Just remove the fuel pump fuse and run until it stops to relieve the pressure. All the lines I replaced were fine, just paranoid The fuel lines on the 944S and 944S2 don't require the wheel well surgery to replace I formed the damper lines by bending the line into the "J" shape and clamped in a wide jaw wood vise and left them for a few days to take the shape.

plumbum

For me it is a sign it the rubber is cracking it won't be long until there is damage to the hose it it covering..an early warning (and reminds me I have to check mine again )

jhowell371

The hoses underneath the insulation sleeves looked fine. No cracks in the outer rubber layer and the Teflon inside was like new. I think the lines of the Turbo and Series 2 cars even more so than Series 1 cars suffer from exhaust manifold cooking and the hardline/rubber junction at the engine compartment is what fails, spraying fuel on the exhaust manifold. The S and S2 seem to have a better fuel line arrangement. Since the DOHC models were developed last maybe Porsche rethought the fuel lines. JMTCW.

RJ80

Great, guys... thanks for the help. Trying to decide if this is a job best left to the pros or something I want to tackle myself. Seems straightforward enough, but my S2 is nearing 30 years old and I find there are usually surprises in store!

porscharu

The fuel line is a polyamide (nylon) core with a vulcanized rubber outer. The OEM hose is a cohline 3124.0800 (link here) and Roger at 928srus stocks it. I was not able to make it work for the dampener lines since they were formed from the factory and kinked on the tight bends. When a nylon fuel line kinks they are done and cannot be trusted to hold pressure. I ended up salvaging the factory ends and having my hydraulic shop mount some stainless teflon sections with silicone heat shield over the manifolds. You can definitely do this job, just remember to counter wrench the lines. Best of luck!

jhowell371

I got the tight J bends done by bending the line to correct shape and clamping it a wide jawed wood vise to help keep the line from kinking and to hold the J shape. Couple of days in the vise and the lines were ready. They have been on for about 2 months and are doing fine, no sign of kinking. I got my fuel injection hose at Napa.