Tranny hose size?

[A1Avette79]

Does anybody know what the hose size is on a '79 (Auto with air) Tranny oil cooler? I am replacing the radiator tomorrow and figured I would replace the hoses to and from the Tranny cooler.
Thanks

 

[Hib Halverson]

They are not hoses they are steel pipes.

if those pipes have been replaced by hoses, be careful....very careful.

The only hose that would be safe at the line pressures common with automatic transmissions is braided stainless steel covered rubber.

 

[TimAT]

The steel tube is 5/16. The 74 and the 77 I had both had short pieces of rubber line in both the inlet and outlet to the cooler just behind the radiator nipples. I replaced the rubber hoses on both cars with hose marked "Trans Cooler". GM used that hose for the cooler on lots of their front wheel drive cars, the run was too short for all steel lines, and needed to have lots of flex.

Any rubber hose exposed to heat, oil, and pressure cannot be expected to last forever- and 250 PSI of oil that's running around 190-200* will find the weak spot quickly. Just like the fuel line between the frame and the fuel pump- use the correct one, keep an eye on it for deterioration, and drive on.

 

[VetteV8]

The cooler lines are indeed steel lines, but near the radiator there are short runs of hoses, got to be, as the engine and transmission move, and the radiator with inbuilt cooler does not [I hope! ]

Anyhow, there is virtually no pressure in these lines, as the line from the transmission is the return line, and from the cooler, it flows back in the sump.
That does not mean however, that gardenhose should be used
Cor

 

[TimAT]

The trans cooler sees line pressure from the trans- it varies with road speed and load- if you have an 82, or have installed a 700-R4 trans, when the TCC locks up, the pressure to the cooler will jump about 125 psi. Makes for a great diagnostic tool too- visual proof the TCC has the capability to lock-up. Put a "T" in the cooler line, install a 300PSI gauge and go for a drive.