Has anyone replaced the underhood fuel hoses with hard lines?

[Autobreza]

My 944 is an 85/2, with fuel lines crossing over the valve cover and exhaust header.

I'm looking at way to completely eliminate the fuel line fire hazard by replacing the fuel hoses with hard fuel lines that would never need to be again replaced.

Has anyone done this? Is it a practical approach given the retail kits available?

Other than adding a slack/loop to allow for engine movement, I don't see any reason why it couldn't be an effective and permanent solution. Insulation over the line would be required given the location over the headers.

[944 Ecology]

Sure, go for it, let us know how it works out...

[OK-944]

This sounds intriguing.

Maybe go metal to metal at the wheel well location, then route along chassis to the firewall (avoiding engine vibrations and over-header heat), secure firmly to firewall, at which point either metal loops or short, rubber vibration-dampening hose sections could be installed...secure these firmly on the drivers side of the valve cover - then finish up the runs with metal...tucked in along the drivers side of the fuel rail but leaving room for spark plug wires. Might call for a slight re-engineering of the fuel rail? Or maybe the final fuel line runs could be integrated into the fuel rail? Hmmm....

[v2rocket_aka944]

fuel lines need replacement every 10 years or so and take what, 30 minutes?

[Dean924s]

I would not go metal loop. The constant flexing due to the movement of the engine (even if it is very small) will cause the metal line to become brittle and crack.

[BoxsterGT]

I am following this with interest.

I have made up hardlines previously for the 944 using Cunifer tube, which is a Copper Nickel alloy, but placed it only where there is no movement or flexing.





Another possible way is with Polyamide tube.

This is flexible and can follow another line when used as a guide.





Of course, it is commonplace to use SS or Alum tube in the Tunnel of the 911 models, and I have a host of custom fittings for this application.



I am happy to help if lines or fittings in Metric or AN are needed. Porsche fuel systems are my specialty.

Please email @ len.cummings at verizon.net

Good luck.

Len

[Autobreza]

Thanks for the feedback. Obviously there are pros and cons to routing 100% metal lines.

As Dean924S wrote, without a method of allowing for non-destructive movement, fractures will almost certainly occur over time. I was thinking of movement loops,, such as used with hard brake lines near the master cylinder, but for fuel I am not so sure this is viable.

As v2rocket_aka944 wrote, once you have made the first replacement, future replacements are quick. So cost - which is rather trivial given the benefit, is the only real consideration going forward. I would consider the hoses a periodic replacement item in this case.

I'm going to do a bit more research into what the best industry practices are for designing pressurized hoses and lines for other applications. Might be an idea or two there.

This article has good baseline information: Hose and tubing assemblies.

[9FF]

It’s just not a good idea to have a hardline attached to anything that vibrates or moves constantly, even with a vibration loop it’s far from ideal. Imo the factory had the best solution on the S2 when they finally fitted replaceable flexible lines to the hardlines running from the fuel tank, though I wished they still kept the routing like the very early models and not running over the exhaust header.

Saw this posted in a FB group this week, looked like a nicely kept 951.

[OK-944]

Ouch!

I've also seen examples of soft fuel lines run up from the wheel well location, back around to the firewall, then forward. Takes longer lengths of fuel line to do this...but at least gets them somewhat further from being right over the headers.

[Fast Freddy 944]

Was he vaping too much? Nah, Dam I have a 951, I better mind the fuel lines and give a good going over and see what going down..

[peteb]

Hi,

I think sometimes we attribute 944 fires to fuel leaks when they could just as easily be caused by oil leaks.

I totally agree that maintenance of fuel lines is important. They like to fail from the inside out, so it is hard to tell when it is time to replace. I replaced my damper to rail jumper hose. I looked fine outside, but, was totally cracked on the inside. I also replaced the original over the exhaust hoses. They were okay on the inside after 25+ years. I cut the hoses open to inspect.

Peter

[walfreyydo]

Changing out all the engine fuel lines (from the wheel well forward) should be the first order of business for any 944 owner.

[Autobreza]

Decided to replace the feed and return line with one of the top quality kits mentioned here, and replace the fuel rail jumper line with a hard line so that will be a perpetual fix.