This has been a very interesting discussion on Tranny coolers.
I subscribe to the theory of putting the cooler on the return line back to the tranny. By the way on my 5.3 the line on the left (sitting in the drivers seat) is the return line. I don't know if the 4.2's are the same or not. As suggested the easiest way to test is to remove one line and turn over the engine, depending which line you remove and where the fluid exits from, will determine which line is which. My guess would be that a 4L60E is a 4L60E so it wouldn't matter which vehicle it is in.
Now to my question. I have a Tru-Cool in my truck with a cold temp bypass built into the cooler. Has anyone taken Air temps and Tranny temps using an internal bypass in a Tru-Cool Cooler? I would really be interested in some numbers. For additional information I live where winter temps sometimes get to -40 (at that temp it doesn't matter whether is F or C). I have not had this cooler covered and I have not had any tranny problems in the last half dozen vehicles I have had using this method.
I know that heat kills transmissions but I am not sure that you can chill out a tranny. On a cold start at -40 everything is cold for at least a little while. Even if it ran a little cool for awhile, because tranny's generate their own heat eventually they will warm up and evaporate any moisture. Water will evaporate at 160 degrees it just takes a little longer than when it is at 200.
I have a ScanGuage connected to my truck and have been monitoring TFT for the past 12 to 14 months. I have NOT installed my PCM4Less unit yet but will do it this spring. This is what I found in general:
+20 to +30c in general the trans temp will run approx 190f to 200f on the highway (and up to 210f - 215f sitting in bumper to bumper) with 2 people in the truck.
- in the same temps When towing my trailer with 3 bikes and 3 people and loaded with gear, it is about 200f-210f freeway and generally 220f'ish in bumper to bumper. On long grades in the mountains I have seen it hit a high of 225-230f, when it goes above 220f I usually slow it down. And I am climbing it in 3rd (not OD)
in the +10 to +19c range the are in the 180fto 190f range with 2 people in the truck and 20f warmer in bumper to bumper
- when towing it is still in the 200-210f, doesn't seem to change
in the 0 to +9c range the temps are now at 150-160f with 2 people and I have NEVER seen it above 170f even in bumper to bumper
- when towing at this temp it is still in the 190-210f range
from approx -10 to 0 the trans temps are in the 150-160f range but it takes a really long time to get there (approx 15km of highway driving). bumper to bumper traffic no longer has affect on trans temp
- towing at this temp is in the neighborhood of 180-200f.
from -20 to -10c temps still make it to 150-160f but takes even longer. My commute used to be approx 120km for 1 way and it would take about half the drive before it got to those temps, so approx 60km.
- never towed at this temp
from -30c to -20c temps would make only 140-150f and would take my ENTIRE 120km commute to get there. It does get to about 100f VERY EASILY but from 100f up to 140f/150f it takes forever.
I never drove at -40c so cannot tell you what it would take.