Hey everyone, I found a decent 239 to put in the car. I disassembled, cleaned out the sludge and resealed, and its running awesome, good oil pressure and everything. (In hindsight, I would've just taken it somewhere to have it done as it took me a year of weekends to finish it myself!) There was alot of rust and sediment in the block and rad. Flushed out what I could see with a pressure washer and some prestone flush when it was finally back in the car. Not alot came out after using the prestone. I'm thinking there's still probably alot of rust and gunk in the block and rad. Whats the best stuff to use for a good cleaning? Has anyone had any luck with vinegar? I know in other applications it works awesome to dissolve rust and minerals but I don't want to use it if it's going to hurt the water pump or anything else. Any advice? Thanks!

Strictly opinion with nothing to back it up but I'd stick with the products made specifically to flush the system for the reason you mentioned, concern for the water pump seal.

I've always just used the GM stuff so I don't know about the Prestone. Is it the type that you dump in and run for about 15 minutes or so? I know when you do the GM stuff it seems to work well but wow does it smell bad/powerful.

Thanks guys! I'll try again and see how clean I can get it. And definitely will do do the heatercore. After 75 years there's probably alot of gunk sitting in it