Marvic Magnesium rim question

[nukem996]

Hi all
i have just bought a secondhand set of marvic penta magnesium wheels from a reputable secondhand dealer.
i saw a couple of digital shots of the rim pre purchase and was re-assured by this dealer that the rims were faultless.
when i recieved the rims i immediately noticed a large resin/glue patch on the inside of the rear rim (!)
the glue patch is hidden when the tyre is fitted (so you know where "inside " is). I called the dealer and asked why this patch was on the inside of the rim?
he said it was nothing to worry about and he knew these wheels from 2 other ducati 996's and they are perfect. but he could not explain what the patch of glue was from.
there is a large thin patch of glue about 12 square inches and quite thin. the other patch which is quite close to it, is a bit thicker, about 1/16. but only 3 square inches.
am i missing something here.
i have sent marvic an email to ask them about this......
is this a balancing trick used sometimes. or should i be putting these suspicious looking puppies aside. i peeled some of the glue off and the magnesium looked ok. the rest of the wheel looked ok corrosion wise.
help!!!!

[nukem996]

the rim was cracked and somebody tried to hide it. i had the wheel crack checked by an NDT specialist.
the moral of the story.
be wary of secondhand wheels made out of aluminium or magnesium.....

[kar_the_terrible]

My guess is that if you know a good machine shop in the area that works on cylinder heads... they might have some way of inspecting for cracks.

The do need to check for cracks in cylinder heads and do that with a pressure test (im not sure if this can be done on wheels). But some shops that have been in business for many years generally have more hi-tech equipment that might work in your case. These places are normally also big on customer service... so just try your luck. Definitely better than eyeballing the wheels, and maybe cheaper than throwing them away.

[mydlyfkryzis]

While I'd be wary of cracks, it may be that the wheel was porous there and leaked air. I had an aluminum rim like that. Kept losing air, but no tire leaks found. Put a small amount of Tire slime in and the leak went away.

The tire dealer went nuts trying to find the leak. Remounted and rebalanced the tires twice. I got tired of going back.

So there may be a porousity in that area and they just sealed it.

I would still have it inspected for cracks though./

[BuzZz]

The do need to check for cracks in cylinder heads and do that with a pressure test (im not sure if this can be done on wheels).

Sure there is. I think they call them tires.

[BuzZz]

Sorry..... couldn't resist.....