Originally Posted by
Andrew R Stewart
here's what I would do. First strip out the BB, cranks, post and such to have unrestrained access. Then Clean the outside as well as I could with solvent. Position the frame so that the "crack' was at the lowest point of the ST. Now add a thin liquid to the ST so a puddle sits on the inside at the "crack". Wrap a piece of paper around the ST at the "crack" wait and see if any liquid stains the paper. I'd consider using a penetrating oil. If there's seepage then there's a crack.
Safe, simple, no special tools and can be done at home in the living room if needed. Best is that if there's no crack the further rust prevention step has already begun. Andy
Well, I did exactly that this evening. There was a small hole at the bottom of the seat tube (purposeful - about 5 mm across) where it is welded to the bottom bracket tube, and holding the frame in place with a piece of filter paper from the coffee pot wrapped around the potentially cracked area I poured about a half a cup of WD-40 down the seat tube. I didn't have any other penetrating oil and I'm sure good ol' WD 40 was not ideal - but what the hell I really wanted to figure this out.
Using my finger I plugged the hole at the bottom of the seat tube and let the frame sit for about five minutes, angled towards the side of the crack with enough WD-40 to clearly fill up the tube above the level of the potential crack. After five minutes there was no seepage and the filter coffee filter paper was dry. Removing my finger the half a cup or so of WD-40 spelled out on the grass. So? Maybe no crack. I'm going to take it to a local friend builder and have him check it out because I'd like the frame repainted anyways at this point now that all the components are off it. Again, I'm sure WD-40 wasn't ideal but it was the best I had and I figured if it something was going to seep through that would do it. Thanks for the advice!!