The Stovebolt Site Forums The Shop Area Engine Shop Block drain

The 1955 235 engine I bought had lots of rust in water jacket. So far I've blown it out as best as possible with air pressure, but plan to use a solution of muriatic acid I've seen on here and then flush with a soda solution. Right now the problem is that I can't get air through the port where the block drain screws in. I've even put an air fitting there and pressurized with 120 PSI with no air coming through. Does the water passage go toward the rear of the block? I've tried to use some stiff wire to scrape out the build up. What ideas does anyone have about getting flow through this passage?

If you can't clear the block drain, you have the typical solid deposits at the bottom of the water jacket. The drain hole is at the very bottom of the water jacket.
There is no magic solvent which will effectively dissolve this hard stuff.
If you have the head off, you can use a long steel rod down through the coolant holes at the top of the block to break up these solids at the bottom of the water jacket. It will be necessary to remove the water pump and all of the expansion plugs from the sides and ends of the block to do a thorough clean out.
Carl

I ran across a product at Home Depot called Zepp. It breaks down rust but it is pretty corrosive. I had an old rad that I tried it on and it worked. However, it would be a real killer on brass.