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MG MG Y Type - Fuel Filler Orientation

Hi Guys,
I have been doing a little research on venting fuel tanks to avoid the dreaded blowback when refueling. I stumbled across an old thread (2006/7) by some Y typers on this topic and in particular the orientation of the filler cap. Well my take on this is the filler cap orientation is actually dependent on the orientation of the filler pipe. The filler pipe has an off centre inner tube for the fuel and the space between it and the outer allows for venting to avoid blowback. The vented section should be at the top and therefore the filler cap orientation will be whichever way it has been sweated onto the outer. So all theories whether the cap hinge should be at the bottom, top or to the left or right are correct!!!

Paul you will be pleased to hear the filler pipe you gave me in 2003 is being restored and the cap orientation follows your aerodynamic theory of hinge to the rear and release tab to the front!!!

Can anyone advise how far the inner pipe extends beyond the outer? I don't have this extension piece so will need to fabricate one!
Cheers Richo YT3208
R A Prior

Hi Rich

I have just looked at the pipe that came off Y4099 and it all looks 100% orgininal with no cuts. This pipe is about to goback on my rebuild Y/T. Both pipes are co-terminous, that is they end at the same point.

That said, I know the pipe in Y 5270, the inner pipe extends some 4 to 6 inches (as the end is steeply schampfered) beyond the end of the blow back pipe.

I would be interested to hear from others on this too.

Personally though Rich,as to how to avoid blow back at the pumps? Just fill slower. The Y tank isnt that big - 8 UK Gallons (9.6US Gallons, 36 litres) so just watch while you fill. Its not like you are filling the pick up (Ute)with 30 gallons.

Paul
Paul Barrow

Hi Paul,
My problem has been my filler pipe has no breather at all, just a straight length of copper pipe! I think you are correct with the extension piece, around 4- 6 inches long, just long enough to reach into the top of the tank. I think it may also be slightly tapered as well as the big chamfer. I think a lot of Ys have this extension piece missing because as far as I know it is not a single continuous length and the extension is only a push fit and ends up rolling a round in the bottom of the tank! The extension is not essential but it is better to have the fuel exit away from the breather entry to avoid fuel going straight back up the breather. Either way as you say a slow fill is pretty much mandatory!
Cheers Richo
R A Prior

I will try to take some pictures of the double pipe for the record.

I like too the idea of a detachable second pipe but currently do not have the ability to pull mine out of Y 5270 so if someone else has the ability to do this and comment, please feel free to do so and come back to us all with some comments. Let there be Ys does not say much about the filler other than it consisted of a tapered metal pipe, closed at the top end by a moulded filler cap.

Paul
Paul Barrow

Hi guys,
If it is any help I have attached a picture of a filler pipe from a YB. The inner pipe starts approx. 1inch down from the inner lip and finishes flush with the outer pipe at the bottom end.

Keith D Herkes

Hi Keith

Great photo of the top end and sorry I have taken so long to get a photo of the bottom end folks, but now you have it.

The $64,000 question now is "is the extension tube simply a push on that has, over the years, fallen off both Keith's pipe and mine?" and "If so, does anyone have one they can give the dimensions on?"

Paul

Paul Barrow

Another pic for you. This is the bottom end of pipe, as it came off tank, with the rubber connecting pipe in situ. There is no evidence of an extention either here or in the tank. Until this thread, I was unaware of an "extention" to the inner pipe.

Keith D Herkes

Same as mine there Keith.

Maybe I will dismantle the one in Y 5270 ... this is getting interesting. It may take a day or two for me to do it as I am still not allowed to bend after the surgery though!
Paul Barrow

Hi. This is what's in my YA. The 2 slide into each other. Image supplied.

andrew sorouni

Hi Andrew

It is kind of hard to tell but I am guessing that part of the smaller piece is a rubber sleeve that you will fit over the tank neck?

Is your main tube a tube within a tube still?

If so, then can you please measure the extension where the one (inner) pipe is longer than the other (outer) one please as this is the bit that is being questioned here. My back is still too painful for me to contemplate taking mine out of my Y at this time for this thread.

Thank you

Paul
Paul Barrow

OK. The length is 14.5 cm to the tip, 9cm to where it is cut back and the outer end diam. from tip to tip measured 2.5 cm

andrew sorouni

Great work Andrew - this looks very similar to what I recall mine looking like.

Does it look like it is an integral part of the inner pipe, or does it look as if it has been pressed up onto and over the inner tube?

Paul
Paul Barrow

it goes right into the main pipe and is welded at the edge where both pipes meet. If you look down the pipe you can see 2 pipes, so when you are filling up petrol, i guess the petrol will flow in both the main and the outer part of the extension pipe...possibly for better breathing.
andrew sorouni

Hi Guys,
An update from me. The extension piece needs to terminate at or just short of the top of the tank, any longer and it will be very slow to squeeze in the last few litres. I have been doing some measurements and got 150mm which confirms Andrews figure of 145mm. Next step is to make an extension piece and method of fitting. Options are butt welding if I can find someone with the skill to weld light gauge pipe. The other option is fit the pipe inside the inner and drill and plug weld or drill a small access hole on the breather side of the main pipe that will allow access to insert a small tapper screw. A hole at the bottom of the outer is not an issue because it will be covered by the rubber joiner to the tank.

Also I have looked at a couple of other Ys and I was surprised to see niether had a complete inner tube only a semi circle to create the breather space. Unfortunately because they were in the cars I could not see what they were like at the bottom end.
Cheers Richo
R A Prior

This thread was discussed between 28/06/2011 and 17/07/2011

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