77 308 Heater Hoses Replacement.

I have a '78 and have been searching awhile on this subject. I managed to find the instructions below. Apologies for not capturing the name of the person who posted it.

Seamus


The T-fitting and the attached return hoses, under the cowl, can be pulled out for access, but it isn’t easy.

Try this:

1. Remove the passenger side heater core, to gain access to its water return hose, and remove the hose. I didn't find it necessary to remove the driver's side heater core but it wouldn't hurt.
2. Remove the drivers side heater core return hose.
3. Attach new hose to the liberated ends of both old heater hoses. It might help to coat the new heater core hoses with silicone spray to help them slide into place. You will need abut 4-feet of new hose for each side to facilitate installation. I pushed some vacuum hose inside the ends of the heater hose, as a flexible alignment dowel, then used 2-loops of tie wire, through the ends of the mating hoses and 90 degrees to each other, to wire them together. After tightly twisting the ends of the wire and bending the twisted ends against the hose to minimize the chances of the twisted ends from catching on anything, I then wrapped the joint with a layer or two of electrical tape to again make sure the wire didn’t catch on anything.
4. Loop a 4-foot length of strong cord or light rope over the driver’s side heater hose and tie the ends together, forming a loop. Slide this length of cord along the length of the driver’s side hose, about half way toward the T-fitting and thread the tied end of the cord to the central area of the cowl where you can grab it.
5. The idea is to pull the cord toward the right front head light of the car, causing the driver’s side heater hose to kink or buckle. Simultaneously, pull the large, central return hose, and push the new heater core hoses toward the T-fitting. With some work, the T-fitting, with its attached hoses, will emerge from under the cowl. Continue pulling the hoses until the new hose ends become accessible.
6. Cut the wired ends of the new heater hoses off, remove the old hoses from the T-fitting, fit the new ones and you are ready to re-insert the hose assembly.
7. Alternately, pull on each heater core hose and push on the larger return hose until the T-fitting is back were it should be.
8. Trim the heater core hoses to length, install them on the heater cores, and then reinstall the heater boxes.