FLUSHING THE COOLANT OF THE 74

14 | 03 | 16 | 20:52 | Filed in: 1974 Cadillac Coupe deVille | Restoration

I had replaced the heater core recently as it was leaking and it was disconnected when I got the car. As I did not know when the cooling system was flushed for the last time I wanted to flush everything before I reconnected the heater core.
I first flushed everything with a cooling system flush chemical followed by fresh water and then I put in all new coolant (I used Prestone) and connected the heater core to the system again. Everything came out very clean, so I think that a good flush was already done a short time before I got the car.
It took a while until I got the air out of the system and the new heater core did not work at first. But after about 30 minutes of letting the car idle at about 2.000 rpm, the air was out and the AC finally blew out warm air.
Its great to have heat in the car again.

When I reconnected the heater valve to the heater core I needed a short piece of heater hose. I found perfect reproductions at Fusick - they look exactly like the original GM heater hoses with 5 ribs and are available by the foot. They are not exactly cheap, but perfect replacements if original appearance is important for you. They are also available in the correct size - 5/8 and 3/4. The smaller diameter goes from the heater core to the hot water valve.
By the way - Fusick has exceptional customer service , which impressed me very much. I will definitely buy from them in the future again.

Fusick offers a perfect reproduction of the original ribbed GM heater hoses. The original heater hoses had 5 ribs just like these super nice reproductions.

I re-connected the new heater core to the cooling system and used correct reproduction heater hoses to connect the original heater valve which is still working perfectly. The hose clamps are not the correct ones yet. I think there should be tower style hose clamps which I do not have at the moment. There is still an original one on the bottom of the valve and also one on the other heater hose, thats why I´m very sure that the other two clamps should be tower style as well. I have not found a perfect reproduction clamp yet, but I´m still looking…