The Imperial has a large heater box mounted on the firewall inside the engine bay. This heater box contains the air conditioner evaporator, heater core, fresh air inlet, and blower fan.
The heater box is made of a fiber reinforced plastic – you can tell by the strands of fiber visible on the surface. As you would expect of 50 year old plastic in the hot under hood environment, it has not aged gracefully. Fortunately it is still solid. Unfortunately it is looking tired and weathered.
The obvious thing to do is paint it, like I’ve been painting everything else in the engine bay. The issue with this is that the textured surface would look horrible – the fibers would print through the paint and make it look like a poorly prepared surface. This closeup shows the visible fibers.
You can’t sand it, as this would just expose more fibers and damage the existing finish.
Preparation for paint would require multiple coats of high build body primer, with sanding between each coat. The final result would be a completely smooth surface – which would look good, but would not look original.
Searching the Internet, I found references to surface renewal treatments for plastic. These claimed to actually soak into the plastic, retaining the original surface texture and details. I decided to try Eastwood’s Plastic Resurfacer, which claims to “reflow and resurface faded and chalky surfaces”.
After thoroughly cleaning the heater box I applied several light coats according to the instructions.
The end result is quite good – the heater box still has the factory texture, but now looks like a new piece. Time to install it and move on to the next project!
Next: More Shiny Bottom