Anyone ever use polyethelene tubing from the building supply store? Is this what the factory fuel lines are made of? I want to finish the work on the tunnel and this is one of the things I need to take care of.

Do NOT use poly from Home Depot for fuel lines. It"s a car not a sink. You can use aluminum tubing sold by Summit and other parts warehouse / mail order folks.

Thanks for the reminder. Should I also return the Deco faucets I installed in the dash? I appreciated the note of caution. But I think the factory material is polyethelene. The wall thickness looks the same. I'm wondering... IF .... the stuff is the same why wouldn't you use it? The factory stuff lasted 30+ years. I'm not worried about any racing rules. Frankly the only reason I'm changing the lines at all is I kinked the factory lines where they passed through the bunkhead and accidently cut one with my sawsall .

I've heard that as the fuel runs through the aluminum it causes the tube to sweat which causes the tube to oxidize were it touches the metel in the tunnel. Anyone using aluminum have this experience? My other thought about aluminum is to encase it in shrink wrap. I bought some shrink tubing once about 4' long from a surplus store. If you use aluminum are you using any special installation methods?

So you go ahead and use the Home Depot stuff and your car burns up and it happens in your garage and your house burns up. The insurance company does a little investigation and finds out you used tubing made for water for your fuel line. And you say "well it looked the same to me..." Sorry, they're not going to pay for your house or the medical bills for your family.

The aluminum lines do not sweat when fuel runs thru them. If your worried about oxidation, paint it or put a sleeve over the tubing. My car has aluminum lines and it bend and forms very easy. Use grommets when you run it thru the sheetmetal.

Get real-the fuel lines are not a place to be cheap. If you don't understand this maybe you shouldn't be working on it. Sorry to be so blunt but maybe you've never see a car burn.

The cross linked polyethylene stuff the sell @ HD is pretty tuff stuff. It is rated at something like 1200psi. Not sure whether fuel would melt it though.

Mark

73 2.0

Buy a small section of it and drop it in a gas can to see what happens.......the type of plastic it is made of might react to gas. Some swells or goes soft when in contact with it. If in a week nothing has happened...give it a try....you have nothing to loose except your car & house.

I'm an Mutli-line Insurance Adjuster.... There is no exclusion in the policy for stupidity. I think my insurable assets and family are safe. Thanks for your concern. Besides. I can always reference this post in my defense. I'm attempting to conduct research so I'm no so ignorent. The product use label on the display listed fuel as one of the uses. I was just wondering if anyone used it. and if so why or why not. I'm not willing to accept that the line is for water so don't use it. People used to say the earth was flat so don't sail past the horizon you'll fall off. Out there on the Gold Coast you can leave your car out in the driveway for 8 months in bare metal and never worry. Around here that's not the case. Go to any salvage yard around here and check the aluminum bumpers on the 1980's model GM cars. They are completely rotted off the metal mounts. Electrolisis is an issue here. Now lets be nice or we'll both end up in the time out chair.

Rich-

Don't forget about varmit poontang chewing on the lines when they find a nice place to hiberate on the shores of Lake Superior!

Tom

Good thread. I would like to see the outcome of this. I have used braided lines for years (teflon style not rubber) but its not cheap to do. I normally go out of my way to find good used lines. None of this is under any real pressure. Test a section of it and let us know.

Several people I know have pulled new rubber lines all the way through the tunnel and used nice grommets to protect it.

B

What about using stainless bendable hard lines (not braided) like Summit sells in rolls very similar to the aluminum tubing? I can't decide between the 2. I'd post a link but it doesn't take. Part # is SUM-220256.

Stainless solid lines would be a very good way to go. Truck brake hard-lines are a good cheap source.

I wouldn't use braided-SS in the center tunnel. You have to keep checking in there to make sure they aren't starting to abrade anything. (Hey, notice how the middle of "abrade" is "Brad"? )

Note that, in a 914 with a front-mounted fuel pump, one of the center tunnel lines is under full system pressure. (29-40 PSI, depending on the car and setup.)

--DD

Oh.. yeah. I knew there was a reason why I never moved the pumps to the front (or dealt with 75-76 cars).

Stainless sounds like a good way to go. Little more work than dragging rubber lines through the tunnel, but sounds safer.

B

I just replaced my lines using the stainless steel brake lines described on the Pelican Parts website and Dave's post. The materials were pretty cheap (~$30), even buying twice as much tubing as I should have needed after an early FUBAR (OK ~$50). It was only a minor PITA once I figured out that there needs to be a couple of bends back towards the firewall (this isn't described in the technical article).

And the real moral of the story:

If I can do it anybody can.

Huh? Fuel wont melt it, but HEAT will...

When I did my fuel line swap I tried the hardware store polyethylene tubing as you are considering, for the same reasons. DONT. The OEM lines look like polyethylene, but they must be soimething different. Take a hair dryer to it and watch it melt before your eyes. There is alot more heat back there than a hair dryer and its a sure-FIRE way to lose your car.

I ended up using thick-wall aluminum tubing from the same hardware store. Its used for refrigerator water lines and other uses. Very durable, bends easy (unlike the steel and SS brake tubing, and is quite inexpensive. 4 years now...no problems. It even fits right through the original rubber grommets in all locations. The plastic lines in the center tunnel probably will never need replacement.

Thanks for agreeing with me Bowlsby. I tried to tell the guy not to use the poly stuff and he gives me the finger. Nice guy.

There is a reason that SCCA only allows hard tubing or SS hose to pass thru the passenger compartment. Because it it the proper material for that application. Summit has aluminum tubing in thier on-line catalog and CB Performance has SS braided lines on-line.

Paul

http://www.mazzerplastics.com/ComCh_tubing.htm

It says POLYETHYLENE tubing is okay with gas.....BUT, you also have to figure that you are introducing pressure to the calculation as well now.....I totally agree with Paul, not all tubing is equal, the HD stuff might not have as strict tolerances and who knows if the walls could be too thin at certain points, hell, a garden hose might work as well, but I sure as he// won't be using it (high performance fuel line, 10X the fuel capacity as the stock tubing!!!!!)

For the CIS, at what point is the gas pressurized? Stock /4 was in the 30psi range...CIS is closer to 70psi or higher I thought. I'd use whatever line they used on the 928's.

I've had stainless tubing on a few of my past 914/4's.

URY914, He who lives in a glass house... (or fiber glas house pun intended nice car) I'm looking for facts likes bowlsby and others provided. I would not use the tubing in the engine compartment except the short section that comes through the rear bulkhead. No exhaust heat problems there. I only wanted to replace the tunnel section because of damage. I thought about attempting to replicate the 90 deg. bend at the bulkhead using my heat gun. I guess I would have figured the melting thing out soon enough. But that's the info I was looking for.

rich,
Why did you even ask when you're going to use what ever you want anyway? Forget what I and others said about using aluminum tubing or SS hose. Go for the poly stuff . I guess it was my fault for replying to your post in the first place.

Paul

URY914, Like I said I was looking for facts based on knowlage not speculation. The idea isn't totally off. It looks like others have considered using the poly lines. It doesn't appear anyone followed through. I just conducted a pressure test. I measured the O.D at a marked segment on the tube. It measured 12.87 mm I installed quick couplers and connected it to my compressor. I remeasured the tube a 150 P.S.I the tube measured 12.89 mm. I also put it infront of a 300 watt Halogen lamp. I got the same measurement. I also melted the factor line and the poly line on the glass of the halogen lamp. same result. the wall thickness is actually thicker on the new poly line. Draw your own conclusion I guess.

I think the only way to give the finger to anyone on this board is to or :finger2:

For facts and knowledge, one would need to contact the manufacture of the tubing, just by going on the premise that someone here said they have used it with no problem is not good enough when it comes to safety unless a large enough majority in varieing enviroments have tested this tubing. Also, the tubing from HD might be different coast to coast.


One thing I do not like about the plastic line is that you have no ridge or lip for the hose and clamp to secure against. If you use a regular cheap @ss hose clamp you have a great chance of the hose slipping off of the tubing....I've had this happen with the factory plastic line since the PO used the wrong hose clamp.
If you or anyone switches to a hard line (SS, Copper, Aluminum, etc....) a small flare should be made at the end of the line.


You have too much work into your car to save $5 bucks

ChrisReale, HEY! YOU WEREN't GIVEN ME DA BOYD WAS YA! (lol) That's what I did. But I decided to edit it out. It was kinda immature. But then I did say something nice about URY914 project.

Mueller, Thanks for the input. Did you see my pressure test?

New question on the same subject.

Would you remove good factory lines on your STREET car and replace them with hard lines if there was nothing wrong with them?

I'm not convinced I should pull my factory linesand toss them. Maybe I can add a hard line to replace the 8" end piece I damaged.

I have seen the cross linked polyethylene installed. They use a tool that resembles a exhaust pipe expander. Pump the tool 3 or 4 times and then only have 30 seconds to install a barbed male adapter. Once the polyethylene returns to its original size it is permanent, no clamp required. The fittings are probably only probably only available in standard 1/4", 3/8", 1/2" pipe thread. From what I understand they have been using this stuff in Europe for 25 years. Just got accepted in US building codes in the last 5 or 6 years.

What can I say, I sell houses for a living. Too many This Old House re-runs.

Mark

73 2.0

Mark,

This method is exactly what Porsche used for the BRAKE lines that go into the master cylinder.

B

Ya, What MarkV and "B" said just ran a bell. My BMW 2002 has this type of line running from the master cylinder fill tank to the hydraulic clutch slave. No clamps.