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MG MG Y Type - Boot skin rust cause.

Y3348 was bare-metalled just a few years ago, and yet I've found rust bubbles at the lower outside edge of the boot lid. Not a spot of rust anywhere else on, in or under the car. Annoying.
This looks to be the cause - not great photos, but the double-skin around the bottom edge of the lid has separated; water can sit (even in warm Qld) along the bottom body channel, and weeps into the separated portions of skin - then sits inside the bottom of the bootlid, eventually showing as rust bubbles on the outside. At least I think this is what's happened.
I have no seal (as recommended in archives) along the bottom edge where bootlid meets body. There is a metal strip, 25mm wide along the bottom edge of the body that doesn't look original.
So two questions : (1) is the metal strip at the bottom of the opening a non-original add-on? - it does catch the lip of the boot on closing, so I'm tempted to trim it back a bit or remove it.
(2) Has anyone experienced similar water ingress into the boot lid, and have any suggestions to offer?
My initial plan is to clean out the double-skinned lip areas where they've separated, treat with rust-kill, carefully dress back together, and seal with a suitable flexible sealant. Longer term, the rust bubbles will have to be excised, at which time a more permanent fix will be in order.
Interested in anyone's thoughts. Thanks as always. John H.





J P Hall

There should be a drain hole in the centre of the boot lid to keep the inside cavity dry, however moisture will still find it's way to the gap between the skin and inside the boot lid. You might treat the area with metho to absorb the moisture and then treat with phosphoric acid followed by a seam sealer or rust preventative. There is also a sheet of "deadening material" inside the boot lid that can trap moisture.

The cars were I believe fitted with a seal around the boot lid, but this often blocked the drain hole in the lid a deteriorated quite quickly - the lip on the opening worked with that seal to prevent exhaust fumes from entering the car.

ALL older saloon cars should always be driven with a partially open window to prevent in ingress of exhaust fumes - a silent odourless killer.

I have an excellent collection of rusty Y-Type boot lids - the problem is real.

Cheers

Tony
A L SLATTERY

Thanks Tony - I'm glad I'm not the only one. The boot lid rust is particularly galling because, as you well know, so much effort is put into making everything good during the total restoration - only to be undone by a double-skin boot design that sat quietly waiting to rear its ugly head.
The solution for now has been as described in my initial post - clean out the separated areas of lip, treat with rust-kill, and apply seam-sealer. I also trimmed back (by 5mm) the 25mm strip at the bottom of the boot opening - it was catching on opening and closing the boot, and definitely contributing to the problem.
Today's pictures attempt to show the temporary fix. Ultimately, I fear I'll have to "pay a man" to excise the rust bubbles in the lid and let in new metal; at which time I'd say we'll clamp the double skinned lip back together and run in a seam of weld.
I hope this is of interest - the bbs seems a bit quiet these days.
John.





J P Hall

... and the problem rust bubbles, from the outside of the lid. SO annoying after an otherwise successful and satisfying restoration.
John.




J P Hall

Not wrong there John - many people prefer the instant satisfaction of our Facebook page rather than using this great facility which is easily searchable and provides a great archive service. However, we try to keep the website fresh and relevant too to provide a service to all.

Paul
Paul Barrow

I hear you, Paul re. Facebook. My take on the f/b page is that it's fine for a quick snapshot of Y-related goings on; but that this BBS is an invaluable "clearing house" for (generally) more technical reports, questions and discussions. Contributors have built up a tremendous resource of combined knowledge, meaning that the Archives are there as a a permanent library. I would even like the facebook page to somehow remind its users that "for more detailed discussion of Y Type questions", the BBS is recommended. It's a wonderful resource, and I hope it long continues, running parallel to the quick snapshots on facebook.
Just my (Aussie) two cents worth.
John.
J P Hall

John
I noticed with horror that you don't have a sealing rubber on the bottom edge of your bootlid--needs fixing. Yes leave a little 10mm gap for the drain to work but that rubber seal right round the lid needs to seal to the body right round---

willy
William Revit

Willy, you refer to a sealing rubber "on the bottom edge of your bootlid". Do you mean on the double-skinned lip of the lid itself where I've just put sealer? - or in the aperture at the bottom?
I was thinking of putting a strip of u-shaped rubber (from Clarke Rubber) along the affected lip, as extra protection.
I don't remember seeing any reference in Y Type books about a seal on the lip itself. I reckon it sounds like a very smart idea.
Thanks as usual.
John
PS - off shortly to the UK's Beaulieu autojumble and hopefully heaps of other MG/Triumph/Lotus/Sunbeam ... old car events!
J P Hall

I 'think' originally the rubber seal sat in the trough right round the bootlid, but whatever you can do to make sure the lid is sealed against the body right round---also the spare wheel door--that has the seal in the trough on the body.
Exhaust fumes are the enemy, both lids need to be sealed up otherwise the fumes get sucked in. I lost a friend a few years back from one of those stupid zip out rear windows in a softtop mgb---we don't want a replay of that if we can help it.----fix it now while you're at it, doesn't matter how but make sure it's sealed up when it's shut

Off to the UK eh. That's a bit special. Have a good trip fella.

willy
William Revit

Interesting, Willy that both you and Tony S highlight the issue of fumes. We never drive the Y without the 2 front windows open a few inches. A bit less in the rain.
So that's two good reasons to work on proper sealing around both bootlid and spare wheel cover. Later in the year I'll finish the job and post a pic. Thanks always for your input mate. John.
J P Hall

This thread was discussed between 13/07/2025 and 25/07/2025

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