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Petrol Feed Pipe Connecting Thingamy (ptfe?)


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Today's 'Battle of Bromley' is man v (reinserting refurbished) petrol tank - especially that stiff new rubber filler neck.

 

One Q, when re-attaching the fuel outlet screw-in thingamy to the bottom of the tank (which was a pain to unfasten), should I be applying anything like little ptfe tape or polymer to make sure it seals ?

 

TVM

 

 

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Hi Austin,

ideally no. The olive should seal it when it is pinched up.

However it has been known for the tank part to be a little rough and so a turn or two of PTFE tape may not go amiss.

 

Was it leaking before you took it all apart?

Did it have tape on it?

 

If 'no' to the above then don't use the tape.

 

Roger

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If it refuses to seal a new 5/16" olive will be needed.

 

Has your car a solid fuel line to the double ended connector by the LH rear shock or has it been modified to a short bit of rubber connecting the tank to cross car pipe.?

 

Think about a 149556 (item 42) from a TR5/6 and add in the rubber connector to link it to the cross car pipe. http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/fuel-system-induction-controls/tanks-pumps-pipes/fuel-system-tr5-tr6-to-c-cp50000.html

 

Cheers

 

Peter W

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I wouldn't recommend PTFE tape.

 

Used PTFE tape around the pipe connecting thingamy when I fitted my new tank and I ended up with a petrol leak and white stringy stuff in the filter bowl of the fuel pump a few weeks later. Seems that PTFE may claim to be fuel resistant but is not up to constant immersion in the stuff and will dissolve, like it did with me.

 

When I refitted it (after taking the tank out) I used Hylomar Advanced Formulation which is a fuel resistant gasket and thread sealant. No issues since.

 

It should seal without sealant but a small dab of Hylomar (or Wellseal or Heldite) should be all that is needed.

 

Phil

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It would be worthwhile to heat the olive, if as I suspect it is copper or copper alloy, to anneal and soften it before reuse. Get it so hot that the flame goes green before quenching in water, or just letting it cool on the bench.

John

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It would be worthwhile to heat the olive, if as I suspect it is copper or copper alloy, to anneal and soften it before reuse. Get it so hot that the flame goes green before quenching in water, or just letting it cool on the bench.

John

They are usually brass or alloy of.

Stuart.

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No No OK

 

Although PTFE TAPE is supposed to be virtually indestructible, it will soften when immersed in fuel and will 'run'.

Use PTFE tape in a 1000 applications, but, not this one.

 

Any proprietary liquid seal (a couple are recommended in this thread) would be best, if you feel the need

 

In an ideal world, you shouldn't need it

Edited by wjgco
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They are usually brass or alloy of.

Stuart.

Stuart,

Brass is an alloy of copper and zinc, with a few other components, depending on application.

I don't know what alloy would be used for an olive.

 

Do you think that it's a bad idea to anneal it?

John

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John,

 

I agree that brass is a copper/zinc alloy, but if heated till the flame turns green the zinc will burn out. I don't know if those olives are copper or brass, but I wouldn't risk annealing it.

 

Pete

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OK, Pete, the voice of wisdom. Annealing brass seems an every day task to Americans who reload their ammunition by reusing cartridges.

YouTube is full of videos

But they don't heat it to a green flame, but to see a colour change in the brass.

So maybe that's the way to do it.

Thanks!

John

Edited by john.r.davies
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The opposite I think. needs to be soft, so that if conforms to the pipe, & seals around it.

And yes, I would anneal it first, or buy a new one (TR shop etc)

 

Bob.

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but to fit a new olive would i not need to replace the solid pipe as i would lose the flange on the end ?

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the top end of my brake pipe appeared to have a very slight flare - i had assumed to stop olive leaving me ?

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I thought we were talking about FUEL pipe ??

 

Brake pipes have flares, fuel pipe going into tank does not, it is a plain pipe, with a female coupling nut slid on, followed by an olive, the pipe is pushed up into the fitting on bottom of tank which has a male thread, the nut is then tightened up to squish the olive onto the pipe, thus sealing it, & retaining it.

 

No flare.

 

Bob. (have a nice day!)

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The opposite I think. needs to be soft, so that if conforms to the pipe, & seals around it.

And yes, I would anneal it first, or buy a new one (TR shop etc)

 

Bob.

These types of fittings are generically known as bite type fittings and the olive is a 'bite' ring.

The bite ring has to perform 2 functions;

- seal, which is the obvious one

- prevent the pipe blowing out of the fitting under pressure

 

As the name suggests the bite ring is designed to bite into the pipe, to perform the function of retaining the pipe.

The bite creates a small cut in the OD of the pipe, deforming a 'bank' of material in front of it. This holds the assembly onto the pipe.

In order to do this, the bite ring needs to be harder than the pipe to which it is fitted.

 

Over tightening will deform the pipe and is as bad as undertightening

Every joint should be assembled, taken apart, the bite ring checked to ensure it is tight and the pipe checked to ensure there is no collapse.

It can then be reassembled.

Edited by wjgco
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John,

 

I agree that brass is a copper/zinc alloy, but if heated till the flame turns green the zinc will burn out. I don't know if those olives are copper or brass, but I wouldn't risk annealing it.

 

Pete

 

Where did you get that information from Pete - I can't find anything published on it? Annealing brass will require anything between 450C and 750C depending on the alloy. It is normal to silver-solder brass at temperatures of around 650C which is red-heat. There are no ill-effects that I am aware of and all the bits I have silver-soldered seem to be fine.

Edited by RobH
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So To be clear if you need to sort this out you will need a new olive and check that the pipe where the old one sat hasnt deformed.

Stuart.

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