Reducing Cockpit Heat

by Carl Priess

Originally published in the Austin-Healey Magazine, June 1987


I was interested in reading Layne Perkins' Tech Tip regarding BJ8 Heater Valve Replacement; a few months ago I performed the same operation on my BJ8. However, I went one step further.


A valve fitted to the heater water return line allows the heater core to be completely isolated from the unwanted flow of hot water in the cooling system. A neat installation that looks original, only a concours judge would object.

Eliminating any source of unwanted cockpit heat is critical to comfortable motoring in a Healey, especially when living in a warm climate. While the car is funning, hot water can get into the heater core from the return line even with the controls in the "off" position. Therefore, to insure that no hot water could enter the heater core, I added a valve in the copper return line 50 that the entire heater system could be isolated.


For summer operation, I drain the radiator to the level of the shut-offs; all shut-offs should be open including the heater valve. This drains a fair amount of water from the heater core and the feed and return hoses. Then close the shut-off on the block and in the return line and refill the radiator. Now, no water can pass through the firewall to the heater core. This not only reduces heat in the cockpit but also extends the life of the heater valve considerably. In the fall, merely open all shut-offs and top up the radiator to the proper coolant level. The heater is now ready for normal operation.


A valve fitted to the heater water return line allows the heater core to be completely isolated from the unwanted flow of hot water in the cooling system. A neat installation that looks original, only a concours judge would object!


For those doing this separate from the replacement of the heater valve, the procedure is as follows:

  1. Drain the cooling system to a point below the joint of the copper return line and the lower radiator hose.

  2. Loosen the hose clamps securing both ends of the copper return line.

  3. Loosen and remove the 9/16” nuts securing the return line mounting brackets.

  4. Unsnap the water temp gauge line.

  5. Pull away the return line.

  6. Cut the return line roughly midway between the mounting brackets and flare the end of the front section.

  7. Install the valve to the front section and then cut and flare the rear section to fit.

  8. Now, in true British fashion, perform the reverse of steps 1-4.


I considered putting the valve in the hose just before the hose passes into the firewall but felt it was most secure in the copper line and appeared esthetically correct.


The cost of parts is approximately $4.50. Tools required:

  • Hacksaw

  • Tube flaring tool (I borrowed one)

  • Screwdriver (For hose clamps)

  • 9/16" wrench (For copper line mounting nuts)

  • Adjustable spanner (For valve installation)

Not what you were looking for? Don't forget you can check our back issues using the AHCUSA Magazine Index.

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