Here's a question for Dave, but others may have some insight as well. My '67, 440 cid (Imperial engine) has newly replaced freeze plugs, and a lot of casting sand and junk in the cooling system. Prior to doing a closed system flushing with "Cascade", I want to get most of the garbage out using a garden hose on the lower radiator hose, thereby avoiding the redone radiator. We all know 15-18 psi is what a radiator cap opens at. However, my garden hose may be as high as 25 to 30+ psi. Can the head gaskets, etc. and inside of the engine take that kind of pressure? Does anyone know what pressure exists inside the block? Or would I be wiser (with this old , tired engine) to just throw an old radiator on and do a closed system flush? Any other drawbacks to my open system flush? Thanks for any input. Dan Richardson 300L Family Heirloom ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm