Relocate the Heater

So much for waiting for bad weather before dismantling things; I made a start on moving the heater matrix to the other side of the firewall.

Heater box relocation is both to improve the heater operation with hopefully more downdraught & to provide a little more space behind the aux panel in the cabin for some other alterations.

My firewall even had 4x holes centrally, presumably for attaching the fusebox in its factory standard position? Marked out the shape of the matrix intake, intending to use the 20mm metal punches I used on the bonnet vents for the corners then join up the straight lines with the Dremel:

Not too bad, however, drilling stainless is a mare, 4mm pilot opened up to around 8mm both using my right angle drill attachment in the confined space. The step drill wouldn't have it, so ended up using 10mm metal punch followed by 20mm metal punch. Joining up the straight lines with the dremel extension was much easier:

Heater matrix relocated to the engine bay, with the fan box virtually in its original position - but saving around 1" of space on the cabin side of the panel. The wood blocks on the second shot are temporary to make sure none of the loom touches the firewall while I am drilling/cutting and generally getting things hot:

The heater matrix will take fresh air from the bonnet immediately above as per standard layout on most cars. This requires a box on the engine side to ensure no engine/under bonnet fumes make their way in. Mocked up in cardboard first:

Then aluminium, a little fitting required and patches to cover existing old firewall holes. Not shown here rubber trim between the cover & heater matrix & also neoprene seal to the bulkhead:

Water could make its way down through the, to be cut, bonnet vents. The bottom of the vent box is designed to slope away from the firewall & a marble double checked which side is lowest before drilling a 4mm drain hole:

Final step, rivnut fixing to the firewall so its all removable if need be:

Next up - re-plumbing the water feeds, holes in the bonnet & some rubber edge trim to make the top edge seal with the bonnet.