Back in the day... When my 300-L started overheating, I worked in an automotive shop. One shop night, I drained and flushed the system (into the center drain, back ion the Y&D days) but it was still "muddy" inside. I then poured a gallon of battery acid in and ran it with that for a while. I added more water and kept it running then opened the drain and ran it for a 1/2 hour or so with water running thru it from the hose. This did a great job of cleaning it out, but didn't get the "mud" deep in the block out. Later When I opened the drains on the side of the block, they didn't drain. I pulled out the freeze plugs (OK, welch plugs) and used a coat hanger and air and water pressure to clean the block passages out. Replaced them with Brass Marine plugs which are still there today. I remember that at least 2 plugs had rot holes in them, and the only thing keeping in the water was the Mud. Not recommended for many reasons, but it worked for me. Ray \ On Sep 2, 2009, at 4:40 PM, Richard Barber wrote: Acidizing chemical plant process piping to remove corrosion and deposits with minimal attack of the good stuff is done with inhibited muriatic (hydrochloric) acid--often with heat and almost always with circulation. I would not recommend it for motor vehicle (c3oo)ling systems as the inhibitors prevent attack of metallic components and are carefully selected and dosed for the job. Disposal of spent acid solution must also be done carefully to protect the environment, eyes, skin, paint, garage floors, sewer piping and the wastewater treatment plant. If you decide to play boy chemist, rubber gloves and goggles are recommended--as well as plastic (not galvanized) buckets to catch the cleaning solution. C-300'ly, Rich Barber 1955 Chrysler C-300 [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: mailto:Chrysler300-digest@xxxxxxxxxxxxxxx mailto:Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/