Gen 3 transmission cooler line size?

[AdaMerlock]

I’m hoping to fix a transmission leak by replacing soft lines but I’m not sure the diameter, apparently they’re 11/32. Also don’t these transmissions have a thermostat to them? It seems to only leak while driving so I didn’t know why it wouldn’t leak cold

 

[MontySquareo]

I think the fittings on the radiator are 3/8 but I would go measure before I start spending money

 

[CharlieNorth]

Technically the fittings are 10mm, so we do the best we can with what we have.
The fluid required in these transmissions is very "harsh" on common off the shelf hose. Pay attention to what you intend to use.

 

[Michael Brown]

It likely leaks while driving because the viscosity of the fluid decreases as temperature increases. Also it is under pressure when running.
When it cools, it is thick enough to not leak through the gaps.
The ZF transmission oil reaches the consistency of water at its peak operating temperature around 95C.

PartSouq has OEM hoses, if you are concerned about the material or size of an SAE hose.
PartSouq Gen 3 Transmission Cooling

 

[CharlieNorth]

Keep in mind the cooler circuit is not turned on when the transmission is cool.