If it weren't for bad luck, Under tank connection Options

[NARP74]

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.

[Superhawk996]

Some very cursory poking around seems to suggest fiber washers meant for fuel get vulcanized. Maybe I'm over thinking it.

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.

[NARP74]

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.

[NARP74]

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.

[Flyinlow]

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!

[NARP74]

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.

[bdstone914]

@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.

[DennisV]

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.

[NARP74]

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.

[NARP74]

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.

[DennisV]

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.

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.

[Steve]

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

[NARP74]

@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.