I just completed a coolant drain and fill on my 21 1.5. Here was my procedure and some tips. I started by draining the system at the radiator petcock. Be extra careful as this a plastic valve. I had to remove the air tube at the bottom of the radiator to get a clear path to the petcock. Be gentle, I used a 7/8th socket which fit perfect on the valve. I drained apprx. 3 quarts, refilled with distilled water and did this 2 more times, added cleaner on the fourth, drained, refilled 2 more times…
I just completed a coolant drain and fill on my 21 1.5. Here was my procedure and some tips. I started by draining the system at the radiator petcock. Be extra careful as this a plastic valve. I had to remove the air tube at the bottom of the radiator to get a clear path to the petcock. Be gentle, I used a 7/8th socket which fit perfect on the valve. I drained apprx. 3 quarts, refilled with distilled water and did this 2 more times, added cleaner on the fourth, drained, refilled 2 more times…
Coolant drain and fill