Set to flush d4400 and pony... how valuable is a pony head?

I don't think pony heads go bad too often - so not that rare. But - I used a high pressure washer for about 30 to 40 minutes on my pony coolant passages. That stuff was really caked in there.

My point is a flush alone might not get it. The speedo cable might work. A pressure washer or steam cleaner on the "jet" ( not "fan") setting could help.

My experience has been that a washer wand in there with the head off lets a lot of gunk come out the adjacent passage holes rather than getting flushed deeper. You may want a change of dry clothes.

I have the pony jackets clean I need to flush out the main engine block without putting the gunk back into the pony. The old speedo cable and a drill done a good job with compressed air ....WA7OPY

Set the system up today works like a champ. The wall of the pony head was over 3/16 so plenty of meat to tap. Ran the garden hose into the head full blast, put air into the block water drain to mix things up good, rusty water out the water pump hole back in to a 50 gal drum. When the drum was full in went the H F pump and around and around the water goes. Boy did it rusty fast. Will let it run 24 hrs or so then will flush with clean water and then go to a smaller can and citric acid. Tonite I will clean up the rad....WA7OPY