Dave928S

It seems it's an interference fit in the existing hole, and the flange sits against the inside face. Other than the interference fit in the existing hole, I don't see how it will seal. Can you elaborate on how you propose to pull it against the inside tank surface, and keep it there, and what you'll do to ensure the sleeve fit is correct, and leak free.

BauerR

When you thread the pickup and tighten it to the proper torque, everything will be held into place.
Understand that the only place that prevents fuel from leaking out fo the tank is the pink/red gasket located on the pickup. The seal is created on the outside lip of the tank, not the threads in any way.

SeanR

Actually the molded portion that the threaded piece is in plays a part of the sealing of the tank. Hence my comment above. If that is compromised due to the threaded portion being stripped out, you will have a hell of a time with sealing, long term or short term.

I like what you are doing, should be interesting to watch.

dr bob

Some thoughts:

The part you are making needs be very secure on its own, with no movement available once the nipple is installed and tightened. Consider how the mass of fuel pump and inlet strainer are hanging off the inside end, and whether the piece you are making will walk around as fuel sloshes etc. It can't. There will be some nozzle loading on the outer end from the connecting hose bit it will be minimal compared with the overhanging pump and strainer inside.

The actual liquid seal is provided by the ring gasket that is squeezed between the lip of the tank nozzle and the nipple that threads into your part. Distortion from any movement of your part in the tank risks distorting that ring gasket and a leak.

If you aren't going to make your fitting a tight fit in the tank nozzle, and even if you are, consider making your part long enough that you can hold it by reaching through the level sender opening on top. That way you can keep it from turning as you tighten the nipple without adding any radial loading at the inside end, as you will with that tab if you are depending on it to keep your fitting from turning.

docmirror

I would maybe suggest radiusing the hub to flange interface and using a Buna-N seal, or maybe a rubber ring bushing to seal against the inside of the tank rim around the hole. Guessing you may need a bit of crush seal back in there. Just an idea, looks like a nice upgrade ya got there.

BauerR

The inside lip will wear the same gasket that you would find out the outside. So, it will seal from the inside of the tank as well as have additional cushion against the inside of the tank.

BauerR

The overall fit will only be .005 smaller than the original threads, so the fit will be very snug

GregBBRD

Seems like a reasonable approach to a problem area. Good brainstorming!

If you are going to make this a product for other people to use, the overall length of the inserted portion will probably depend on the differences between tanks, which are bound to vary, because of how the tanks are made. This should't be too big of a problem, since the inserts could be modified for each individual tank.

Consider cutting a groove into that aluminum shoulder to retain the inner seal, so it can't slip outward....it's soft enough to slip outward and cause a leak....if not initially, then possibly in the future.

If you are going to market this, make sure you understand the legal implications and exposure very well. After all, the original inserts worked very well in the beginning....and they only come loose because the 30 year old plastic has gotten hard and is failing....not because the original insert failed.
Your retention method depends on compression of that hard, brittle plastic.....and the potential for cracks is very high.

A fuel leak, in gereral, is bad. A fuel leak inside a closed garage can be catastrophic. A fuel leak inside an attached garage can be deadly.

I'd predict that the product liability insurance for something like this will cost way more than the actual insert.

BauerR

Thanks for the input. I will definitely consider making a relief cut to help hold the seal. However, chances are I may change out for a stronger o-ring later on down the road, if this goes to production.

No worries, been a part of making far more complicated fuel system solutions for about 20 years now.

www.rossmachineracing.com

GregBBRD

I've certainly used Ross pieces of jewelry to build prototype intake manifolds. Good products!

However, solid aluminum intake manifold pieces are different than clamping down on brittle plastic, when 20 gallons of fuel are above, right?

I'm just pointing out that these tanks are exceptionally brittle. I replace more tanks from cracks than from the inserts spinning! I see so many bad tanks, I keep two in stock at all times...simply because they are usually only in inventory in Germany....and waiting weeks for a tank isn't practical.

In the stock application, the plastic in the tank isn't compressed or in tension...The pump/strainer tightens down on an aluminum insert.

Your design requires sqeezing down on some really old, thin, brittle plastic....and could be an issue.

My comments are only desigNed as food for thought. I hope your design works as intended!

BauerR

Update!

Installed the part... finally. Works exactly how it was designed. No leaks, drips or issues. Put about 100 miles on it so far.

dr bob

Will this gem show up in your catalog soon? I'm sure that a lot of folks will gain comfort knowing they have this kind of thing to backstop their confidence when servicing a pump or strainer. Plus, the rubber ring gasket on that recent clinic car here was rotted and falling out piece by piece. I'm guessing that others of the same age will be experiencing the same failures as time goes on.

soontobered84

When you have to replace your strainer/internal fuel pump down the road, will the leg prevent the insert from turning during the removal? Should the insert have another leg to prevent movement during removal of the strainer/internal fuel pump?

It's a great idea. I like it.

Mrmerlin

I like how your thinking outside the box,
my suggestion for this part would be to remove the square edges of the tang,
this so it wont act as a blade and cut the tank.
As Greg has alluded to,
the tank plastic is brittle and a little bit flexible,
a sharp piece of metal working on a part of the tank could wear through as the flexing of the tank .
Good luck with your proof testing

BauerR

I'm not sure what the final plan for this will be. All I can say now is that it works perfectly.

No need for 2 legs. The one leg will stop the fitting from rotating all the way around.

The photos I posted were before any finishing. This fitting has no sharp edges.