Let me start of by saying I have absolutely no experience with the concepts of working pressures within automatic transmission systems.

Recently discovered at least one of the two transmission cooling lines was leaking.
This is at/near the connection(s) where the metal line(s) connects to the flexible 3/8" ID hose that connect to the trans fluid cooler.
I tried tightening the two screw clamps where the two hoses slip over the end of the metal cooling lines.
This created slightly more noticeable leaking (obvious from more fluid build-up on pavement under vehicle) but not to the point of knowing exactly what the source of the leak(s) was.

So, my next step was to replace both of the flexible 3/8" ID hoses that connect to the trans fluid cooler.
Once I replaced the two hoses, one of the metal cooling lines showed a visible leak, about 3 1/2' to 4" past the end of the metal line, where the hose is screw clamped in place.
The metal cooling line looks like it's in great condition; it has visible no rust, corrosion, damage, etc.

So, my questions are:
1. Since the metal cooling line showed no visible sign of leakage before I replaced the two 3/8" ID hose, what are the odds the metal cooling line was actually already leaking before I replaced the two hoses?
2. Did replacing the two 3/8" ID hose with new hose sections place more pressure on the metal cooling line(s) thus creating a larger leak in the metal cooling line, or creating a new leak?
3. With the engine running, and the transmission in PARK, the leak in the metal cooling line looked to be under extreme pressure as it was shooting straight out of the side/wall of the cooling line, in a very narrow stream likely less than a 1/32" in width but it was shooting at least a couple feet long. That is some pressure. Is it possible there is some type of blockage in the system that is creating some type of 'over pressure' scenario, or is the working pressure of such a system really that extreme?

Thanks in advance for your replies.

 

Assuming you've got TransCooler & two 3/8"=10mmRubberHoses+StainlessTubing similar to pic below of a FrontEnd being rebuilt?
These 2 hose connections are notorious leakers after 100k+ Miles.
If TransCooler fins are leaking, it needs to be replaced, available new\use from ~$40: FordMotorCraft# 5L2z-7a095-a
FrontEnd needs to be removed to get good access to the TransCooler; not difficult just clumsy & time consuming.
Replace old 2Hoses + 4Clamps with new HydraulicHose from your local parts house, rated 200psi\Higher & two WormClamps at each connection (8each).
If StainlessTubing is leaking, cut that back with a PipeCutter, replace with longer piece of Hose & again two WormClamps at each connection.
Finally check your MerconV compatible ATF level after a 15min+ drive, engine running in Park on level ground, top off as needed.
Consider taking this occasion to do a full PanDrop+ATF+Filter service & BandAdjust on the Tranny.
Consider installing a Larger or 2ndParallel TransCooler & ByPassing the RadiatorExchanger for better Transmission cooling, especially if you tow.
Recheck these new parts for leaks over the next several days\drives.
Hope this helps.

 

Thanks for your reply @DILLARD000

Yes, my 2004 Ranger 4x4 XLT does have the factory trans fluid cooler just as you described, and pictured in your photo.
The cooler looks great, exhibits no sign of leakage, and I'm confident it is good to go.
I purchased my Ranger NEW in April, 2004. It had 8 miles on the odometer when I test drove it so, all of the transmission components are original; everything.
Well, it does have two new hoses now. LOL

I'm approaching 155K miles with no tranny service to date so, your suggestion for, full "PanDrop+ATF+Filter service & BandAdjust" is well advised.
I also like your idea about cutting the metal cooling line back past the leak area, and adding a longer hose section. Great idea!
Thanks again for your detailed reply, and for all your great suggestions!!

 

At 155k+ Miles, age is at the point where several common failure items
with the V6~4.0~SOHC Engine + 5r55e Tranny + 1354 TransferCase + ...
are likely to start failing & need to be considered for replacement\service:
~ OilPressurized TimingTensioners
~ Plastic ThermoStatHousing
~ Plastic HeaterControlValve
~ PlasticTanked Radiator
~ CoolantPump+Fan+FanClutch+AllHoses+Clamps
~ DPFESensor, MAFSensor, IACValve, TPSensor
~ PCVValve & Associated Hoses
~ OverDriveToggleButton+Cable in ShiftLever
~ TransferCase MerconLV Drain+Fill + ShiftMotor + ControlModule
~ Diff GearOil
~ ...

 

Called around the area to locate a shop that I was comfortable with to install the three metal transmission cooler lines.

The shop I decided to do the work had these attributes: (1) very good price (2) excellent warranty (3) great reviews.

They removed the three old lines, installed three new lines, topped off the MerconV fliud, and I've been driving the Ranger now since December 13.

I'm very happy with the work this shop performed on my 'old' 2004 XLT 4X4