Auto Restoration 101

Rebuiding a heater box is fairly easy to do. The box on the inside of the firewall holds the heater core and has threaded studs that pass through the firewall to attach the outer fan box. The nuts on the outer firewall box are hard to get to if the fender is on the car. I have seen cars with holes cut into the inner fenders to access the nuts. Most of the time when restoring a car the fenders are removed, making it the perfect time to rebuild the heater and replace the fan and heater core. Mark the control cables that connect to the flaps so you can remember where they go afterwards.

The heater box parts shown are off of a 1965 Buick Wildcat. Most boxes from this era are all typically the same. Once the boxes were removed from the firewall they were degreased and bead blasted to remove all of the rust. They were then primered with an epoxy primer and then painted semi-gloss black with a good urethane paint. The flaps were in great condition and rarely need pulled out for repairs.

This is the outer fan box after it was painted.


This is the inner box that mounts on the inside of the firewall and holds the heater core.

The inside of the boxes were blasted and painted also.

A new seal was made out of some scrap rubber to keep the heater core from sitting directly on the painted metal. The white stuff is some scrap felt that we used to replace a piece of flap foam.

This is the new fan motor and heater core.

The old fan blade needs to be re-used. This one was bead blasted and painted black.

This is the heater core re-installed. We had to re-use the seal around the inlet and outlet pipes because a new one wasn’t available. The old one cleaned up good.

The boxes are now re-installed back onto the firewall. Make sure to use some 3M Strip Caulk around the edge of the fan box to seal it to the firewall. I used some left over windshield tape on this one.