Restoration of a Smith's Heater

Smith's heaters are commonly found on British cars and come in different models. The one that we restored is from a 1960 Daimler SP250. Fortunately, although this is a rare car, the heater is not a rarity. The same one is used in the MGA. That means you can purchase most of the restoration parts you will need.

Some parts that you can't buy new are the heater box, the heater box cover, the heater core and the hot air outlet vent. On most old cars, these will be in fairly decent shape and require only striping and refinishing. If they are damaged or rusted through, you'll need to do body work type repairs or locate used ones.

Our heater box reminded us somewhat of the hollow body of a banjo or guitar, although it isn't entirely hollow. Sheet metal "walls" inside are shaped to hold the heater core in a diagonal position and to create a rounded air duct with the "squirrel cage" type blower motor fan installed near its center. The blower motor is held to the back of the box, behind the blower motor fan, with three screws. Its shaft spins the fan inside the heater box.

At the other end of the outside of the heater box, near the center of the vertical edge, the diamond-shaped flange and the round inlet pipe of the heater control valve are held in place with a painted bracket fastened by three screws. On a diagonal line from there, near the bottom of the heater box, the outlet elbow from the heater core protrudes. On the bottom of the heater box the hot air outlet vent is attached with four tiny screws. This has a hinged, flip-up door with cable connectors, clamps and screws and louvers underneath the flip-up door.

The heater box cover has a lip or flanged end that presses over the heater box. There are indentation in both the heater box and cover that fastened five (on this model) cover clips in place. The approximately four-inch-long clips hold the two parts firmly together. At one end the heater box cover has a large circular opening through which the "squirrel cage" blower motor fan pulls in air. This should be covered with a piece of screening that is held in place by a circular coller fastened with three hex head screws. At the bottom of the opposite side of the box, just above the hot air outlet vent, are two short tubular air hose connectors made out of thin sheet metal. These are held in place with three small screws.

Other Smith's heaters we have seen are shaped somewhat like a beehive or car air cleaner. These have essentially all of the same elements, but the parts are different in size and shape. The restoration process is basically the same though. It boils down to disassembly, clean up, repair or replacement of the bad parts and careful reassembly with fixed-up or new parts. Since the car needed a total restoration and the owner wanted to keep his overall costs as low as possible, he was open to restoring the heater to a "nice" appearance without replacing every part with new or sending parts out for painting or powder coating. In other words, blood, sweat and tears, limited parts replacement and a few cans of spray paint.

Disassembly of the heater started with removal of the spring clips, which pop off with a screwdriver like clips on a distributor (except, in this case both ends of the clips come off). Only the shape of the sheet metal holds the heater core in place. Everything else was taken apart by removing the screws described above. A special "collet" type fastener is used at the end of the blower motor shaft to hold the "squirrel cage" in place so that it won't come loose as it spins. The old gaskets used to seal some parts against the heater box had to be peeled off with a scraper.

After five cover clips are removed, the cover comes off to reveal the angled heater core and round "squirrel cage" blower fan.

Looking at upside down heater box (note "Smith's" name is flipped) you can see motor on right and heater control valve and pipe fitting on left.

This is bottom of heater box with air outlet vent on left and air hose connectors on back. Louver vent is hidden by flip-up door with cable connector.

This is the top of the heater box. Rivets holding nomenclature plates on will be drilled out with Dremel tool bit and new plates will be riveted back in place.

Thanks to the big 60-in. Eastwood media blasting cabinet we purchased last year, removing the old finish from the heater parts was simple. Since media blasting doesn't remove rust, we treated the areas with minor rust with a store bought spay-on rust converter product. We had some trouble with the tiny fasteners holding sheet metal parts on. A few of them were rusted in place and broke off. We had to drill out the holes with our Dremel tool and find replacement fasteners.

All the parts before a trip to the media blasting cabinet and treatment with a spray-on rust converter.

Here's all the heater parts after blasting, rust treatment and refinishing with multiple layers of spray paint with wet sanding between coats.