Cleaning Coolant Transfer Tubes

Time has come to reassemble my Europa whick involves alot of scrubbing and painting. Next challenge: how do I clean the inside of my coolant transfer tubes? 1" ID, 5 ft long, and not straight. I tried looking for extendable wire brushes but didn't find much. The bends in the tubes prevent a  threated extendable rifle style bore brush front working completely, but maybe it's a combination of that and a regular wire pipe brush?

I want to give it a brushing to knock off the loose rust before it plugs up a radiator.  The car has been apart since at least 2002, so it's a little cruddy in places.

You guys are smarter than me, what so you think?

How about a couple of plugs to seal each end after half filling it with a CLR and water mix, then swishing the fluid around a few times over a couple of hours?

Hydrochloric acid will work on the rust a lot faster than it will eat through the metal.  I have cleaned out fuel rails and entire (running!) engine cooling systems this way.

When it is really cruddy, it generates a lot of heat all by itself.  Neutralizing with a baking soda and water flush can also get really energetic.

Seal one end with an expansion plug, tilt it up, and fill with Evaporust.  It will take a few days to remove heavy scale.  I've bought it at Tractor Supply in a gallon jug.

I'd also start with Evaporust. 

Directions do suggest cleaning most of the heavy scale off beforehand, so I'd fill the tubes with about a quarter pound of whatever small little nuts and bolts you have in your junk pile, cap the ends, and turn it end-to-end so that the nuts fall/slide down the sides and knock everything loose. 
Rotate along the long axis every so often so that a new internal face is there for the nuts and bolts to slide against.  

Depends on what what type of rust/debris/sludge you are trying to get out of it. You might try running a string or wire down the length of the pipe, tie a bottle brush to one end of the string and then pull it through the pipe from the other end. May take several times to get it clean. Can also tie a solvent soaked rag and do the same.

I'm glad I posted. So, I'll cap the ends, fill it with nuts from my bucket o junk, then Evaporust for a couple days. I was so hung up on wire brushing, but these should do the trick just fine, and probably easier too.

Thanks guys!

If you knock most of the scale off (do you have a borescope you can inspect them with?) The EvapoRust should do the job in 24 hours.  If not, nothing wrong with letting it sit.

After, you might want to use some clean bolts and shake em through there to make sure everything is clean.

1) Trombone brush with a wire brush duct taped to it

2) Pull a length of chain back and forth

3) Plug one end and fill it full of white vinegar

Myself, I'd probably do the Evaporust. It works and it's reusable.

Just tie a string to a suitably sized bore brush and pull it through a few times.