How to Determine Which Transmission Line is the Return Line On a Ford C4 Transmission

Updated 11/29/2011 | Published 11/28/2011

Question:

For a Ford C4 Automatic transmission. Which line is the return line?

asked by: Greg

Expert Reply:

The best way to determine which line on a transmission cooler is the return line from the radiator is to use the following procedure:

1. Start engine while engine is cold
2. Place transmission shift lever in drive for no more than 10 seconds.
3. Stop engine and remove keys
4. Identify the oil return line by feeling both oil lines. The coolest line is the oil return line.

I am including a link to a FAQ page on transmission coolers.

expert reply by: Jeff D