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MG Midget and Sprite Technical - Fuel tank sender float. Can you buy them?

Actually, this is also a ship in a bottle type question.

But first, can you buy the plastic sender floats seperately? I don't fancy shelling out over 20 quid for a new sender, when only the float is suspect, and may not have anything wrong with it at all.

It's not very clear, but if you look just below the red arrows, you can just make out the level of the liquid in the float. So at first sight, it seems the float is leaking.

However. I can't find a puncture. Even if I leave it in hot sun light, the liquid, which I would assume is petrol, doesn't come out. Nor does it fill with more liquid, if I submerge it for over an hour in 3 feet of water. And if I hold it under a foot of water, hot enough to burn my hand, do any bubbles escape, -- which I would assume they would as the air/petrol vapour inside the float expands in the hot water.

If there isn't a leak, what's in the float, and how did it get in there. Ballast?

So can you buy floats, and do I even need one? It floats well enough, that's for sure.


Lawrence Slater

https://www.holden.co.uk/displayproduct.asp?pCode=070.229
Pete Moreland-Moore

Brilliant, thanks Pete.

Ever seen a float with liquid in it, and no obvious puncture?
Lawrence Slater

Seen plenty with fuel in them, none that weren't damaged in one way or another
Pete Moreland-Moore

Trouble is, they want 13.20 inc Vat, and 4.50 postage. :(.

Yep me too, but this one's an oddity. No visible (magnified) puncture marks, and I can't get any liquid out, or any more in. Ship in a bottle.
Lawrence Slater

Osmosis?

If it floats then I'd leave it.
Chris at Octarine Services

You know Chris, I was genuinely wondering, if over time fuel could seep through the skin of a plastic float. If so, I wonder how many people have bought new senders(for the floats) when they might not have needed them.

I agree. For all I know that amount of petrol has been in that float for yonks, and it might be many more yonks before the "float", doesn't anyomore. So given how easy it is to drop the tank, and the cost of a float or complete sender, coupled with my exceptionally tightly sealed wallet, I think I'll bung it back in again. :).

I only took it out to have a look see, because I had to drop the tank to sort a poor connection to the sender. As a result, I've found a ship in a bottle mystery, and 6 pellets of snake oil in the guise of an octane booster. Ref: "Found this lead in my fuel tank" thread in the general section.

BTW. What coating could be applied to a plastic float, that resists being disolved by petrol, that would seal the skin or any exceptionally small puncture?
Lawrence Slater

Lawrence,

Where did 13.20 come from, the price is 7.80 with the VAT, not sure about their postage cost. I've seen that site before as my neighbour bought one of those for his Morgan. I suggested looking on the internet for a replacement to his leaking one and that was the site he found, he's slowly getting used to looking on the internet for things as he's about 74 now. He was thinking of making one in brass but at that price he reckoned life to too short and bought one. He is quite capable of making one in brass having made a couple of steam locos. The other option was to drain the fuel and try to weld the split with a soldering iron or similar as his was plastic and either end would have fitted the sender loop so even if the weld repair was rough the other end could be used to hold the float.
David Billington

Hi David. I bunged the float in the basket. The site added the vat and postage, and presented me with a total of 13.20. I'll try again.

As for welding it. I would if I could find a split or hole. But even under 10 times magnifaction, I can't see anything suspect at all.
Lawrence Slater

Items:1
cost (ex VAT): 6.50
postage: 4.50
(United Kingdom - Mainland)
VAT: 2.20
total (inc VAT):13.20
Lawrence Slater

Put the float in a pot and submerge it then bring to a hard boil. The end of the wire that the float is mounted on usually presses a smal, hole in the groove. When the fluid is all boiled out (you will have to create a small hole in that same groove) you can use a small pencil type soldering iron and remelt the plastic to reseal it. Round the end of the wire so that it cannot repuncture the groove and go on and reuse it. Zero cost excpt for your time.
Sandy.
DARNOC31

ebay works out about the same price

What about this for a radical idea - film canister !!!
Pete Moreland-Moore

Hey Pete, film canister, that's a great idea, I've got some old ones as it happens. I'll give it a whirl. If the plastic they're made of melts with plumbers solvent pipe weld, I can use it to fix the lid on.

Hi Sandy, I wasn't sure how hot the water could be without melting the plastic, but when I submerged it in water hot enough to burn my hands, nothing escaped from the float at all. I'll try hotter. So you reckon water at boiling temperature then?
Lawrence Slater

I have the same problem with the sender for my B.

The last time I used it, the gauge seemed to be working OK, but that was 1999. I don't know how long it's had fuel in it.
Dave O'Neill2

would petrol melt a film canister? That'd be sad.. :(
Rob Armstrong

As it happens guys and gals, if you can still use that phrase whilst sucking on a fat cigar, I wondered if plastic film canisters were petrol resistant too.

I can now happily report that they are. At least the ones I just got for free from my local film processing shop are. (I couldn't find my old ones in the loft). Not only that, but the lid is such a good snap fit, it's completely waterproof. Submerged it in 3 feet of water for a couple of hours, and none got in. So then I "glued" the lid in place with plastic padding "leak fix", -- which is also petrol resistant -- just for good measure.

All a bit academic now though. This morning I followed Sandy's suggestion and boiled my original float in water for 5 minutes. Loads of bubbles from the water, but not a single one from the inside of the float. The float began expanding like a small balloon as the air/vapour inside expanded, but it didn't give up any of it's contents. It still has exactly the same amount of fluid in it, as when I first looked at it. So Whatever is in there, and however it got in there, it aint coming out, and nothing else is getting in. Hence I'm going to keep using it.

If at some future date, the float does fill up, I'll use the previously prepared film canister to replace it.

How's About That Then? :).
Lawrence Slater

Lawrence,

Any markings on the film canister to indicate the type of plastic?, mine haven't any, if so you can look up its resistance to petrol. If no markings then there are some simple tests to help identify the basic type of plastic. It may just help verify if the canister is going to be OK or turn to mush being subjected to petrol after a few months.
David Billington

Hi David. I tested it by filling it with petrol and leaving for an hour. I rubbed the surface and it felt the same, no "melting" as you get pretty quickly with plastics that do melt in petrol. But that's a good point. Maybe a few months would be enough to eat through the plastic. I'll take a look at the canister for markings and post any I find here.
Lawrence Slater

A bit hard to see in these pics, but the markings on the plastic film canisters are:

A "2" inside a broken triangle.
HDPE
And on the black one the letters "UCP"

Does that mean anything?






Lawrence Slater

Lawrence,

HDPE = high density polyethylene

www.borealisgroup.com/pdf/chemical-resistance/chemical-resistance-hdpe-ld.pdf

gives limited suitability for petrol (gasoline)
David Billington

Lawrence,

http://www.menda.descoindustries.com/PDF/ChemicalResistanceChart.pdf indicates you may be OK with it.
David Billington

I guess that I was not clear. You must first drill a small hole before putting it in water.
Sandy
DARNOC31

Right so film canisters NOT a good idea for petrol floats after all. Cheers David.

If film canisters can't be used, what else could be? As long as it's significantly less than the cost of the 13.20 float below, it would be worth it. Otherwise I guess Sussex classic spares are the best bet at circa 20 quid including postage for a new sender.

OK, got you Sandy. But that doesn't help me then, since I really don't want to make a hole if there isn't one there in the first place. Boiling in water for 5 mins increased the internal pressure enough to cause the float to expand, and that didn't find a hole. So I reckon for all practical purposes my float don't leak. How the fluid got in there though, -- who knows?



Lawrence Slater

Is this any use could be cannibalized if cheap

http://www.ebay.co.uk/itm/MG-midget-AH-SPRITE-FUEL-PETROL-TANK-GAUGE-SENDER-UNIT-BRA960-MODERN-UPGRADE-/200972462003?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2ecae467b3
mark 1500 nearly on the road

As I said above - osmosis - the fuel can and does leach through the plastic over time, you don't need a hole for it to get in there!

Chris at Octarine Services

Yup that is cheap mark. To use that float on mine though it means altering the sender arm. Might as well use the new sender as is.

Yup I think you're right chris. As I said, however it got in there, it took years, and may be many more years before there's enough in there to cause a problem. So it's back in the tank now, which is about to be mounted back under the boot.
Lawrence Slater

This thread was discussed between 06/10/2013 and 09/10/2013

MG Midget and Sprite Technical index

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