This is a continuation from a very long and frustrating fuel pump and fuel line project.
Everything is done BUT...
I have a small leak under the tank on the feed connection at the threaded nut. I did not anneal the copper washer, that seemed like a 50 50 issue and I took the lazy route to get it done. Now that I have several gallons of gas in the tank and have gone for short test drives, I have leakage at that connection.

I have good access to get a crow foot wrench on it and I have leaned into it quite a bit. I am seeing bad things happen if I really wrench on it. Don't want gallons of fuel pouring down on me again, don't ask!

Is there a torque spec for that nut other than the typical German phrase?

For what it’s worth it’s supposed to be a fiber washer not a copper washer.

Hope you can get er’ done without pulling the tank.

Well copper is what came with the new sock I ordered. Hmmm, more bad luck.

Several online sources I checked send the screen with a copper washer. They may all come from the same place. Who sells the fiber washer?

I just installed my new tank, I wasn't able to find fiber washers on any of the 914 parts supplier sites so I ended up finding some at our local Ace hardware. I had to cut them down a little but so far, no leaks...

Will any appropriately sized fiber washer do? Or do they need to be explicitly fuel-safe?

The fiber washers in this kit work but need a slight tweak with a dremel tool sanding drum for a perfect fit. Just did one a week or so ago.

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Good question, I dont know for sure.

When I redid the tank I made the feed hoses so long that I could pull the tank from the car w/o disconnecting hoses. Even welded up the round access hole I no longer needed.

Good luck with the leak.

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I have reused original fiber washers before. If they appear brittle, leave them on the tube/nipple and soak them in water for a short time. They will swell a bit and easily slide off the tube, and be reusable….

This previous link covering where to source the felt washers, and the proper assembly procedure. And more from, my note from above.

LINK:

Gas Tank Line Seals, Seals for the two hardlines out of tank

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Looking at the PET for a 74, the parts description says gasket not washer. That seems to indicate it should be fiber based.

So why is it that no company offers the correct part? All of the ones I see sell a copper washer with a new tank sock. I understand you can buy kits and other gaskets that need modification. But why does no one sell the correct product that just works?

Check with aftermarket VW parts suppliers for fiber washer. Just one example

Oh heck, you did. But where will the rodents live. Man I really like that. I’m going to make a metal cover.
I’m using the original fiber seal. Couldn’t find it new

Check the hole size and just get a guitar hole plug. Keep it simple.

I’m going to speak in the broadest terms and not directing this at anyone in particular.

Because the supply base often don’t understand the original design principles behind why an OEM chose the fiber washer in the first place and think that substituting something like the copper washer is an “upgrade”.

They likely have the copper washers sitting around for other purposes (brake systems, etc.) and don’t want to source and stock another part. Especially a part that has limited application and only sells maybe tens to fifty . . . Maybe a hundred of them a year.

No one is going to tool up a perfect fit fiber washer at those volumes. The generic HF kit has washers that are so close that you’re only trimming off maybe 0.5- 1.0 mm off the ID. It is easily done with a dremel, a hand file or sand paper wrapped around a screw driver.

When you play with with 50 year old cars it’s not reasonable to assume you’ll always be able to find off the shelf parts that fit perfectly without a bit of modification.

Try giving Painters Grinding in Denver a call. I would be surprised if they didn't have the correct washer.

Same for the strainer itself. Cheaper and better fit.

Good call, thx

Have you used these without issue? HF product description seems to indicate they are for water systems. Some very cursory poking around seems to suggest fiber washers meant for fuel get vulcanized. Maybe I'm over thinking it.

What is the proper ID and OD of these? I see photos in the parts vault but no dimensions. They seem to have a wide mating surface if those photos are of originals.

FWIW - BelMetric has several sizes of vulcanized fiber gaskets, if the VW vendors don't have the right sizes.

An excellent idea. Thanks. There are rubber plugs all over this car. This is the one they forgot. A dab of silicone so it doesn’t drop out between uses.

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As luck would have it, or lack thereof in my case, I had two fuel tank strainer kits. I just looked at the other one. It had a fiber washer in it. Guess which one I installed? The one with the copper washer of course. 50/50 shot and I blew it.

I will probably drain the tank, I ran it down this weekend, and take the pipes off and get better measurements.

Yes you are.

Red fiber washers are vulcanized (ie. Formed under heat, pressure and with chemicals that cause the fibers to bind together) but still allows them to swell slightly to seal minor imperfections. Though we usually associate vulcanization with rubber, fiber washers do not contain rubber.

Amazing what you learn when you get determined and decide to go all in. I drained the tank and took both tubes apart. As mentioned by someone before, I did have existing fiber washers already on each tube. They were so old and compressed it was hard to determine that they were not part of the brazed on fitting that the nut fits against. I was able to pry them off but they cannot be reused. They might be original to the car. The car was repainted so the tank was out at one point, but it had copper washers on top of the fiber ones. No way I was going to get that to seal.

Anyway, looks to me like the dimensions for the two fiber washers are;
Larger tube, feed side, ID 10mm, OD 16mm
Smaller tube, return side, ID 8mm, OD 16mm

Those are approximate. As mentioned the old washers were very fragile.

Someone please correct these if I am wrong. I asked AI a little while ago and it said no one had entered them into 914 World. So here they are for future use.

Still on the hunt for great substitutes. McMaster Carr has one size, have to buy 100, but they are cheap. BelMetric has the same size, but not the other. I am sure shipping would suck.

Hi.. I bought a 12”x12” sheet of1/16” nitril and made my own sealed up nice.Hope it lasts longer than me!

I am getting close to that. I can find the bigger one, 10 x 16 at several places. No one likes to make a 8 x 16. I found a bunch in England, France, Taiwan. Most require large quantities and a business account.

Wasn't sure the HF assortment would give me both washers.

AI had me running all over the globe. When I asked to narrow it down to USA, it was more difficult.

@NARP74
date='Aug 18 2026, 04:11 PM' post='3268880']
[quote name='Flyinlow' post='3268879' date='Aug 18 2026, 04:50 PM']
[quote name='NARP74' post='3268876' date='Aug 18 2026, 03:25 PM']
Still on the hunt for great substitutes. McMaster Carr has one size, have to buy 100, but they are cheap. BelMetric has the same size, but not the other. I am sure shipping would suck.
[/quote]
Hi.. I bought a 12”x12” sheet of1/16” nitril and made my own sealed up nice.Hope it lasts longer than me!
[/quote]
I am getting close to that. I can find the bigger one, 10 x 16 at several places. No one likes to make a 8 x 16. I found a bunch in England, France, Taiwan. Most require large quantities and a business account.

Wasn't sure the HF assortment would give me both washers.

AI had me running all over the globe. When I asked to narrow it down to USA, it was more difficult.
[/quote]

The sealing surface on the tank needs to be honed smooth.
Had an install that kept dripping until we honed the sealing surfaces with 400 wet or dry sand paper.
Then i make my own fiber ashers from 3/32 gasket material. Punch when out with a hole punch. Insert the paper disk in the aluminun nut and trace the small hole. Remove the disc and punch the small hole. I use two washers on each. One on top and one below the flange.

I tried rubber and it did not work well. It defirmed when tightened.

Have you given any consideration to a sealant on those fittings?

This has been a timely thread for me, as I'm planing to reinstall our gas tank today. With the insight from this thread and little research of my own, here's what I'm going to try. FWIW.

Use the copper washers Porsche parts vendors are shipping today. Utilize a small amount of Curil T2 (non hardening liquid gasket compound) to make up for any sealing surface imperfections. I believe it's one of the recommended products for the head to copper gaskets to cylinder surfaces.

I'll take a look at the sealing surface.

This was leak free until I went down a huge rabbit hole and relocated the fuel pump. Too many months later almost everything replaced, I used copper washers and I have leaks. Some have said they have had success with copper washers. Not me.

I have thought about a good fuel resistant sealant but stayed away from that because it was not needed a long time ago. I am 50/50 on using it now though.

I found a combo pack on the jungle site that has both washers in it. Waiting for it to show up. I'll see how it goes dry first and then look at sealant if needed.

I am torn between doing what the factory did and then realizing these are 50 year old cars and using modern updates might not be bad.

Should I double up on the washers? On the same side of the install. they are only 1 mm thick. I'm in my own head on this. I just want to be done with this project, have a tight seal and not work on it again for a ling time.

Your dimensions are very close to what I pulled off our original tank.
* ID 10 mm, OD 16.25 mm
* ID 7.8 mm, OD 16.15 mm

Since I still haven't install our tank and have time for a parts order, I'm going to get the Red Vulcanized fiber from BelMetric. They have:
* ID 10 mm, OD 16 mm
* ID 8 mm, OD 14 mm

That's the closest I can find pre-made anywhere.

I converted to AN 6 and AN 8 fittings. You can then run a hose barb. Worked great. I also ran longer lines so I could set the tank on the fender without removing the lines. Down side to longer lines is they can easily get pinched, so I wrapped them in a wire protector.
https://www.cbperformance.com/product-p/3288.htm
https://www.cbperformance.com/product-p/3289.htm
https://www.amazon.com/CrocSee-25ft-Retarda...F9hdGY&th=1 or similar

@DennisV the 8x16 is the hard one to find. I found a multi pack on the jungle site that had both so I ordered it. I have 100s now of sizes I will never use but I was getting close to rally time so I needed a fix. They were a little thin, so I doubled them up. No leaks over 1 month later.
@Steve that is a good way to handle it, but way more involved than what I had time for. I can't tell you how much time I spent on this overall project but I was ready to be done with it. Maybe next time.

I used copper rings on mine, but annealed them first. Many are not properly annealed when you get them.

I couldn't find any sheet gasket material near by so I bought a Holley carb gasket and punched out a pair. Looks like I can get 12 more off of the gasket. And as East Coaster said, copper washers work well if annealed.

Pretty sure I used O-rings, but I worked for Parker for 48 yrs

Barefoot