'Having
just revisited this subject, and although the heater
efficiency improved with the mods back in 2002, the
rebuild of the heater matrix housing has seen yet further
major improvements. It's a must do mod'. - 'Cartman'
20/5/04
OK,
we all know that the heat output and flow from an S3
heater has never been in the realms of a modern car. But
the efficiency of the system is now bound to be way down
on the level of 'performance' 'enjoyed' by when the LR
was new . And it is bound to be worse after 17-30 years
of, undoubted, neglect.
This
page is here to give you some recommendations as to the
faults that I have come across and rectified over the
past 5 years. These changes have resulted in a 100%
improvement in the heater performance from when we bought
Cartman to now.
Yes,
the drivers windscreen even defrosts after 1/2 mile on
those cold Winter mornings (in Central Southern England
:) and the normal heat output is more than adequate, most
of the time.
There
are two factors to consider when looking at heating
system problems:-
Thermal transfer
efficiency (a.k.a. 'How much hot
stuff gets to the air around your feet?')
Air flow rate (a.k.a
how much air is blowing on your feet?)
Getting the
cooling system flushed etc.
Flush the entire
cooling system with a 2 part heavy duty flushing agent (if
your rad or hoses are in any way weak then this will kill
them - they should be replaced for your piece of mind
anyway). Ensure that the heater is
set to the 'hot' position on the dashboard (See
pic) and the heat control valve
above the thermostat moves to the fully open position (See
pic).
Set
the heater selector to 'hot'. The heater control valve on
the cylinder head should then be fully open (Up)
The
first component of the flushing agent cleans the system
through and the second component neutralises the
Alkali/Acid components in the agent. Follow the
manufacturers instructions exactly to ensure that all the
active is flushed from the cooling system.
Some other
publications also recommend the removal of the rad and
reverse flush through. I.E. tip it upside down and shove
a hose in the bottom.
Now
I have done this but it depends on how much crud still
seems to be sitting in the top of the rad after draining
and how far you believe you need to go. If the flushing
agent is used correctly, the majority of the debris
should have been broken down and be out of the cooling
system anyway.
Then
disconnect both the heater matrix flexi hoses and after
connecting a garden hose flush the heater matrix in both
directions with mains water (@ 10-20psi).
Replace the
thermostat. These have a habit of failing open/not
opening correctly or not opening at all. It costs around
£7 to change it so it may as well be done now.But check
the thermostat operates so that it is fully open and the
specified temp, that the 'stat is designed for. So stick
it in some cold water on the stove with a thermometer
placed alongside to check it. Then heat up the water and
voila! Now fit it.
After 2-3 flushes
of the entire heating system (Fill with clean water. Run
engine up to temperature and then drain) refill the
system with quality anti-freeze/water. Ideally, distilled
water (rain water if in a soft water area). Check after
running for a few minutes to make sure the level has not
dropped too much though
Just flushing the
system through improved the heat output on ours but it is
possible to improve it further with heater matrix
modifications such as an additional one fitted in in
series with the original unit or the replacement with
other types. A lot of pipework and sheet metal mods may
be required though. A common option that is mentioned
from time to time on various LR related newsgroups is to
fit one from a MK1 VW Polo, I believe? But my preferred
method was to replace with a matrix of slightly larger
thickness and ,therefore, more heat transfer potential.
And at the same time rebuild the heater matrix housing
and fixing any leaks etc. at the same time.
Improving the air
flow and heat transfer
Assuming that your
fan is operating OK in both speed settings then a check
of the fan entry and exit to the matrix is required. This
can be full of straw, hay etc. after several years of
rolling about.
NOTE:-
switch the fan and ignition off before you stick your
fingers in there!!
Check
the fan inlet and exhaust for obstructions
With the fan
running in hign speed check the heater matrix housing for
air leaks. Bound to be some. Any gaps you find seal with
a smear of high temperature (>90 Deg.C) Silicone/RTV.
Our option though
was to strip out the heater matrix as mentioned above.
The matrix is only held in by four non-captive nuts and
bolts (two through the bulkhead and two through the pass
footwell). So remove the heater coolant pipes, the
4" diameter air intake pipe and then remove the four
bolts. The whole housing can then be removed quite
easily.
The first item we
noticed was the gap between the housing and the bulkhead
and the matrix housing. About 1/4" at the worst
point which was originally 'sealed' by a soft foam strip
when new. This had obviously broken down over +25 years
so wasn't doing much (well, other than
leaking anyway). When the housing is
refitted this gap was made up with high temp Silicone
again (Oooh,
I love Silicone) ;)
This
is the bulkhead matrix housing air hole
The heater housing
could then be dismantled in order to get access to the
matrix and see how badly this thing was put together.
After you have removed around 8 small self tapers you may
wonder how this ever sealed at all! Once the side of the
housing has been removed you can extract the matrix. Note
that this was also orginally sealed around the outside
with the same soft cell foam. Strip out the foam and
place it in the floor 'mounted' circular filing system (a.k.a. 'Da
Bin')
Remove
the original matrix
Now we were lucky
to have aquired another matrix which I had prepared
earlier (sounds like a Blue
Peter moment coming on?!). When these were
compared you can see that the new , and prob later,
matrix is around 1/4" thicker than the original.
More surface area should result in greater heat transfer
into the air flowing through it?
'New'
matrix on the left and original on the right
The new matrix was
fitted into the original housing but this time hard
rubber and high temp Silicone were used to seal the
matrix into position so now the air will go through and
not around it, hopefully. The side of the housing was
also refitted with special attention give to all possible
leaky areas (Silicone!)
The housing was
then refitted and the up to 1/4" gap between the
housing and the bulkhead was taken up with 'the usual' as
well. All securing bolts refitted along with the coolant
hoses and then the cooling system refilled
Improving the
demist and cab air distribution
Now for the big
pain in the a**e job. Remove the demist tube from the
left hand side of the parcel tray (RHD models), the
parcel shelf top tray and the mechanical control cable
from the RH air flow control lever.
Then remove the LH
end of the parcel shelf that covers the access to the
wiper motor. Consult the service manual and lower the
parcel shelf away from the bulkhead.
Remove
the parcel tray and LH demist hose
Once the parcel
shelf has been removed then the heater matrix can be
viewed in its mounting position to the left of the
bulkhead. Check that it is sitting securely on its
mountings and is sealing resonably well in the housing
and the housing to the bulkhead.
Check that the
floor directed vents control flaps are secure and the
sealing foam on the face of the blanking platesis still
in good condition. Replace if necessary. Thier operation
will need to be checked after dash re-assembly anyway.
Clean out the
steel air duct within the parcel shelf then re-attach to
the bulkhead, sealing any points with silicone to avoid
further leaks. Re-attach the heater cables on the RH
control lever and ensure that both the flaps fully open
and close. Replace the cover over the wiper motor.
Refit the bottom
of the LH demist flexible tube and ensure that it is
sealed in place (again, Silicone around the joint and a
large cable tie suffices). Refit the parcel shelf top
tray. Re-attach the flexi hose to the vent pipe. NOTE:-
to improve the air flow to the RH (drivers) I restricted
the air flow to the LH side. The best thing found to fit
into the hole was a used nightlight candle aluminium
shell. Well, that's all I found conveniently to hand. A
3/4" hole cut was through to allow some air flow
..... and then siliconed in place.
Restriction
fitted into LH demist duct
Refit the demist
tube to the screen vent stub and secure with a cable tie.
Conclusions
From
these changes you should see a very marked improvement in
both heat output and air flow. We have to turn the heat
down now !
Each
year I drain and re-fill the cooling system along with a
30% antifreeze/water concentration. (UK readers - Get
your antifreeze from Asda if you can. It's around £3 for
3 litres and is just as good as the Halfriauds (sic)
stuff. Keeping the coolant up to
scratch keeps down the possibility of sludge and
corrosion starting more than anything else.
These
mods were carried out to our SWB S3 WITH A SOFT-TOP! But
if you have an old leaky canvas then trying to create a
better heater may be akin to sticking you finger in a
leaky dam:) But with a good condition tight sealing top
you will be surprised to know but the heater does work
!!!
If
you want still further heat then I can also recommend the
canvas cab screen available from Exmoor Trim. This
isolates the front cab area from the rest of the vehicle
keeping the heat where you would normally want it. Stuff
the passengers ;)
- Paul
How
to get 'something'out of your Series 3 heater 
Updated 22 November 2004
me at pjboomer@_removefirst_freeuk.com
