How do you clean out the rust inside the frame without removing the rust on the outside the frame?

[1motime]

If you could find some rubber plugs the size of all open tubes. Plug all except one at a time. Fill with acetone and let sit . After doing let all tubes drain and blow compressed air. POR 15 is good idea. Just mask off or Plug tubes or it will get all over everything. Messy job but should seal all rust

 

[Andrew Gorman]

I'd scrape out the worst with a piece of metal/Signode pallet strapping. It's free, flexible and tough. Try to shape the end a little bit to match the tube curvature, and maybe tape a section of 1/4" rod or an old bolt a little bit downstream of the end to stiffen it up. I think I might have done this once but the memory is dim. It's so hard to remember anymore... The longest "bottle brush" like things I've seen are for cleaning refrigerator condenser coils, but they are usually plastic, not wire:

refrigerator condenser brush wire - Google Search

Chuck it into a drill to speed things up.

 

[Kombicol]

I would just do the same as you plan for the outside
Spray BLO or pull a rag soaked in it through the tubes
Once dry it will hold the crust in place

 

[62typhoon]

Seems strange they would rerust after a coating of grease?

 

[Lamont]

I agree with the idea that once you get the big stuff out , not to worry about it

There is a product used on road bike frames , for this purpose , Frame Saver I think its called .
you basically have to cover up all the frame openings and spray it in and tip / turn the frame to get it to cover inside tubes.

Other obsessive compulsive road bike guys with steel frames , that dont want to pay for the Frame Saver product , do the same : seal the openings and instead pour ATF inside , then turn / tip the frame rotisserie style to get the fluid to coat everywhere.

If you use either , though you might want to test patch what happens if excess gets on the outside .... might end up staining your perfectly rusted exterior.


Personally, I agree with the idea that once you get the big stuff out , not to worry about it, grease the BB shell interior and seat tube where the post sits and ride on should be fine.

 

[eeapo]

Try these can be purchased at any hardware store.

 

[Gimletbikes]

Try these can be purchased at any hardware store.

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These are especially helpful around that rear, inside dropout area, inside those puckered tubes

 

[1motime]

Try these can be purchased at any hardware store.

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I thought he was trying to get inside the entire frame?

 

[Princeton]

Waxoyl…this stuff is great…you can easily make your own and get creative with the application… https://www.waxoyl-usa.com/

 

[Houndsworth]

I've got this 1961 Murray Meteor Flite I'm building as a rat rod bike, and while it's coming along nicely, there's one problem I noticed between the time I mocked it up, and the time I disassembled it.
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See, when I installed the new bearings and bearing cups to test fit everything, they were all nice and clean, but when I removed them to clean them and grease them, they had turned brown with rust and sediment that was still inside the frame.
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What I want to know is how to get rid of all or most of the rust, dust, dirt and debris inside the frame, without messing up the exterior look of the bike. I'm not stripping this bike down and painting it. I'm not even going to clear it or cover it in boiled linseed oil. I want to leave the bike looking as it is. I just want to remove as much of the interior rust and dust as best as I can, so it doesn't find its way inside the bearings after reassembly. Are there any good, inexpensive ways to go about this? Any help would be much appreciated.

You asked about removing rust from inside the frame, then said you want to do that "so it doesn't find its way inside the bearings after reassembly." Not positive, but I don't believe rust spreads out like a skin cancer. I think rust will occur anywhere on carbon and alloy steel (not stainless steel) if it is not protected from the water vapor in the air. Protection for steel comes from oil, grease, paint, or plating with certain metals. In the case of your bearings - grease them. If there is rust in the tube near the bearings but the rust-free bearings are lubed, should be no problem for them.

But if you are concerned with rust-through in the tubes over time (probably a LONG time), then do the POR15 treatment or if no budget for that, pour some heavy automotive gear oil like 140 weight or 85W-140 into the tubes and rotate the frame so it hits all areas then let it drain. A film of oil should remain on the rust and prevent it from increasing or at least delay it for a few decades. POR15 is a better idea.