This
should have been the final chapter of the heater rebuild! Sadly I had to take a
few steps backwards. First I had to remove the back plate for the bulkhead seal
from the heater unit. Not because anything was wrong with it, but because I
decided it could do with some detail changes.
With the
original set-up the steel tubes supply some of the rigidity to the plate to
help press the seal more firmly against the bulk head. But while measuring an
old seal for remanufacturing purposes, I noticed that even with the original
set-up the seal wouldn't seat properly
against the bulk head! Time for a
redesign of the plates mounting, especially as the coolant tubes don't support
the plate anymore, because they just pass through the original holes without
any physical connection. And the plastic tabs on the heater body, to which the
back plate is riveted, look rather flimsy too. This prompted me to add a second
mounting bracket to the plate. It not only adds stability to the plate, it also
helps with compressing the seal better!
With this
part ready I used the back plate as a template to generate a DXF-file, which in
turn was used by Rubberhuis Maastricht to
fabricate the (cell foam rubber) seal, using modern CNC equipment. They also used
this equipment to fabricated the condensation drain seal, which is fitted
between the bottom of the heater's fan housing and the transmission tunnel:
Next it was
time to remanufacture a new seal to go between the heaters fresh air intake and
the bulk head. For this I also used cell foam rubber, a self adhesive
rectangular profile of 20 x 15 mm. And with four carefully measured 90° V's cut
from the seal, it could be fitted to its designated location:
With all
seals ready and fitted where possible, it was time for the heater's final
assembly; refitting the back plate and fitting the coolant hoses between the
heater's matrix and the pipes passing through the bulkhead. At least that's
what I had hoped for. Sadly even with the fairly slim heater hose I had
acquired, it was still impossible to
negotiate the bends needed to fit the hose between heater matrix and bulk head
passage. Especially the radius for the top hose turned out to be impossible tight
for a proper fit.
Time for another
step back and plan B, consisting of a stainless heater pipe assembly for the
original heater layout, purchased through one of the rather reputable TR7
suppliers in the UK:
Which was
duly cut down approximately in the middle of the pipes, shortening the necessary
hose length considerably. But most importantly this got rid of the tight bend
for the top hose, at least it should have ... The picture above does give a
clue to what's the main problem. The two pipes are identical and much too far
apart in the centre section. As a result of this even with the top pipe hard
against the ventilator motor there still is an almost 10 mm gap between the
rivet holes in the base plate and the ones on the heater's casing, not good!
Luckily I still had the old pipes lying around for comparison:
Clearly visible
is the difference in shape between the aftermarket stainless pipes and the original
ones. And this frontal shot of the assembly clearly shows the rather poor
quality of the work done by whoever fabricated it:
So instead
of fitting the heater to the car I will have to adapt/prepare the original
pipes and use them instead. To be continued, but hopefully not for too long!
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