A labour of love

Heater box rebuild and installation

Heater box rebuild and installation

Bit of a sense of deja-vu with this update – it barely seems any time at all since the last time I refurbished this heater box, but it’s actually something in the region of 18 years! Back then I only cleaned off the rust and repainted it, but in the intervening years the rust had come back and it was all looking quite scruffy once again, so this time I sent it off for sandblasting and powder coating at the same time as I was having the front crossmember done. It came back looking fantastic, there is some rust pitting still obvious in the casing in places, but hopefully the coating will prevent any more rot for at least another 18 years or more.

Here is the refurbished box and cover, along with a brand new uprated matrix, repainted (original) fan, and a new set of seals, all ready for reassembly.

First step was to screw the lower vent assembly back onto the box using new stainless screws, and then fit the new matrix, wrapped in its foam insulation.

Next the cover was clipped back on, using the same stainless clips I had bought new last time (money well spent!). This time I also remembered to fit the rubber grommets to seal the holes where the hoses attach to the matrix – I apparently completely missed them last time.

With the fan screwed back into place it was time for a(nother) new set of decals – I managed to get them with the correct Smiths logo for the year this time round.

With the box reassembled it was just the “simple” task of fitting it back into the engine bay. This is notorious as one of the most tricky jobs you can do on an MGB, but it was actually not too painful for me this time. It certainly helps to have free access to the bulkhead from both inside the engine bay and inside the cockpit, it aids all the necessary wiggling to get the box properly seated and the main rubber bulkhead seal lined up. Once in, it was again screwed down using new stainless screws and fresh gasket seals – see picture at the top of the post for how it looked.

Moving on, it was time to fit the dashboard heater vents and the heater flap that sits behind the centre console. These were pretty scabby as removed from the car previously, but you might have seen them getting the electrolytic cleaning process in my last update, and after some etch priming and a couple of coats of satin black, they all looked as good as new.

The picture below shows these parts back in position, the dash vents are only loosely refitted for now until the main dashboard is back in, when the vent covers will be properly tightened down.

One more little job whilst I was in this area was to refit the heater drain tube (which was apparently affectionately known as “Tom’s knob” on the production line, for unknown reasons 😉 ). The original tube from my car was in awful condition as can be seen below, with a big hole carved out of it (it’s quite possible this was caused by yours truly being a bit careless with an angle grinder at some point). I naively thought that just like almost any other MGB part I would be able to order a new one of these, but I quickly found out that they have been unavailable new for many years, and even used ones were unobtainable at the time I was looking for one.

So I had no choice but to make do and mend. I ran a length of slightly narrower diameter hose down the inside of it to seal up the gaping hole from the inside, and then wrapped black tape around it just to make it look more presentable.

Once refitted to the car it just about looks fine, and should do its job without any problem, until such a time that I eventually find a replacement.

The drain pipe attaches to a tube welded to the bottom of the cavity in which the heater box sits, and is quite a pain to get to – I suspect that without the whole centre console and all the wiring and hoses that normally live in this area removed, it would be nigh on impossible to get to. The pipe is secured by a hose clip which is only accessible for tighetening or removing through this hole pictured below

Update, June 2022: Almost inevitably, shortly after I had salvaged and refitted my old heater drain tube, MGOC Spares announced that they had remanufactured them and brought them back into stock. I might buy one whilst they are available, but then again, given the potential nightmare job of fitting it to an (almost) complete car, I might not 🙂

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