Morris Minor Owners Club

have you been underneath the car to check lines front to back

Thanks for raising this. No, I haven’t checked it for a blockage. It’s the original type cap, but has been fitted with a viton rubber type gasket (presumably at last restoration 8yrs ago). It doesn’t look perished, but it does look past it’s best.

Where exactly is the breather hole located? I’ll have a look and check it before doing anything else.

oliver90owner wrote: ↑Tue Mar 09, 2021 4:22 pm Did the OP check the cap breather hole for a blockage? Can’t remember reading that he did. If that is blocked, the tank will not be ventilated and quite soon be under pressure with modern fuels. Any pressure is likely to allow fumes or fuel to pass any small gap that would not normally pass either.

I checked the back of the fuel pipe after fitting the new tank. No fuel leaks. Haven’t noticed any fuel dripping onto my garage floor from the front of the car. Slight drips of oil yes, but I’ve had that with every A-series car I’ve owned. And only the usual oily smell under the bonnet, no petrol smell.

kennatt wrote: ↑Tue Mar 09, 2021 4:27 pm have you been underneath the car to check lines front to back

MorrisJohn wrote: ↑Tue Mar 09, 2021 4:29 pm
Where exactly is the breather hole located? I’ll have a look and check it before doing anything else.

On that original cap, I've always assumed it to be via the 2 holes on the inside centre and to vent out/in under the edge behind the gasket. They're not always obvious. Take this one for example, Not a Minor Cap, just a single small hole providing an airway past the sealing rubber. The minor one may be this hole: I doubt you've got a blocked vent, but if you've not had the car long, somebody might have inadvertently fitted a non venting cap.
I'd check the seal first, especially if the cap feels loose at all.

So, regards seals, I fitted a cork one which cured the fumes problem - and the Bostic is still holding it in place, despite the doubters! But the remains of the old one, which had shrunk up against the inner convex area of the cap, seemed like a kind of reddish fibre material. As long as a good seal is made, I'm not sure whether the material is vitally important (well, obviously a rice-paper seal would be rubbish! )

Good morning gentlemen. I’ve made the following progress;

- Viton material fuel sender gasket has been replaced with a new cork gasket.

- Filler cap gasket is past its best, though cap isn’t loose when on. It’s currently viton type too. I have a cork replacement, but can’t figure out how to remove the securing chain in order to replace it. Photo attached. (The other end is attached inside the metal fuel pipe.)

- Ventilation hole...I’m not 100% sure to be honest? Can anyone tell from the photos?

Any suggestions on how to remove and refit the chain would be most welcome.

John

That seal looks pretty gone to me.To get the chain off, just take a couple of suitable sized pliers and twist/bend one of the link hooks carefully until you can separate the chain link. Then to put it back together, just bend the link back to where it was so it is secure again.
The two holes in the inside of the cap link to the little opening on the inner rim of the cap for the ventilation.

MorrisJohn wrote: ↑Wed Mar 10, 2021 11:27 am
- Ventilation hole...I’m not 100% sure to be honest? Can anyone tell from the photos?

Exactly as my photo above, but as you asked nicely...

....and as myoldjalopy has said, that gasket looks shot. I thought you had said it was Viton, it looks like very old compressed cork to me. Probably original.

Thanks Gents. That fuel cap gasket has now been replaced too, in addition to the sender unit gasket done earlier.

The only “adhesive” I had handy for the fuel cap one was some hylomar blue, which leaves it free to move around a little. I assume that’ll be fine? I haven’t reconnected the chain yet, if need be I can wipe that off and source an alternative adhesive.

Double checked the filler hose clips are really right too.

Fingers crossed.

Thanks for all the help. Every day’s a school day!

"The only “adhesive” I had handy for the fuel cap one was some hylomar blue, which leaves it free to move around a little. I assume that’ll be fine?"
I don't know, really - it may be a case of 'suck it and see'. I used Bostic on mine and, despite some doubts expressed by others on here, it is still holding fast 18 months later. I note 'geoberni' earlier suggested that '2 part epoxy adhesive, ie Araldite, is fuel resistant when cured.'

Hmm...I’ll see how it goes. I do have sikaflex, but thought it would be a nightmare when it eventually comes to removing it? I’ll see how it goes with the hylomar.

myoldjalopy wrote: ↑Wed Mar 10, 2021 2:56 pm "The only “adhesive” I had handy for the fuel cap one was some hylomar blue, which leaves it free to move around a little. I assume that’ll be fine?"
I don't know, really - it may be a case of 'suck it and see'. I used Bostic on mine and, despite some doubts expressed by others on here, it is still holding fast 18 months later. I note 'geoberni' earlier suggested that '2 part epoxy adhesive, ie Araldite, is fuel resistant when cured.'

Hylomar Blue is only a jointing compound or gasket replacement when clamping 2 components together. It has a certain amount of oil resistance, but usually while clapped down tight like on sump/rocker covers etc.
I can't see it lasting with the cap being twisted on/off periodically.
I've never used sikaflex, but depending on which particular product you have, you could always look it up online and see what it says about oil/chemical resistance.
You need something that is going to set and hold the gasket in place, but also oil/chemical resistant.

Just an update, replacing the viton gasket at the sender unit with cork seems to have solved the problem.

Thanks to all for their advice.