Thanks every one for your input.
After making enquiries of the usual suppliers, it seems that there is no shortage of good quality radiators at a very reasonable price, so it is probably not necessary to have a batch of radiators custom-made at this stage.
The only problem is that members need to be aware that there are inferior products in the market place, and they should insist on the correct part.
The radiator fitted to all versions of the T3 transporter range n Australia is part no 168 121 253 E. Known as the "Tropical Radiator," it was fitted to all vans in hot climates, or vans with air conditioning. It was fitted to 1.9 and 2.1 petrol engines, and diesels, both 2WD and 4WD, from 1984-1992.
Coolant capacity of the entire system is 17.5 litres.
The dimensions of the radiator core are 570mm wide x 440mm high x 45 mm thick. They weigh 8.4 kg. According to the GoWesty and Van Café websites the German manufacturer Behr was the original OE supplier, and they are still readily available from numerous suppliers.
Vans sold in cooler overseas climates were fitted with thinner (30mm) radiator cores (part numbers 168 121 253 or 168 121 253 A, B or C). They will fit a syncro and could be used as a stop-gap solution but will not provide adequate cooling in extreme conditions or when travelling slowly in Gelande gear.
It seems that the euro-spec radiators are being imported by some suppliers in Australia, so it is important to specify the "E" suffix and check that the core is 45mm thick.
These thinner radiators might be advantageous in the snow country, as they will provide a quicker warm-up - an important consideration if you are relying on the demister to clear the ice from the windscreen as quickly as possible (a scenario that I know well as a shift-worker in Orange!) but I think I would prefer the correct radiator, and a removable radiator blind.
I purchased a radiator from Tooley Imports in January 2003, part no. 168 121 253 D. It has a core thickness of 42 mm and has worked perfectly under all conditions - even climbing the infamous Limeburner's track with a tonne on board in mid-summer the temp gauge never moved past half-way, and the second stage of the cooling fan has never been called on. I plan to replace it soon as it is nearly 13 years old, which is tempting fate.
All radiators deteriorate with age, and the alloy fins are subject to impact damage from insect strike and road debris, and blockage with dust and leaf litter. This can be minimised by fitting a mesh screen behind the radiator grilles, and regular cleaning with compressed air. This needs to be done daily if driving cross-country through tall grass, or an insect plague.
Damaged fins can be carefully repaired with a 'radiator comb'.
The grilles are easily removed to facilitate the process. The large screw-heads can be disengaged from their spring clips with a quarter of a turn, and snick back in place with the application of gentle pressure.
The plastic radiator tanks become brittle with age and can fail catastrophically due to vibration on corrugated roads if the unit is loose in its mounts. Repairs can sometimes be affected with epoxy putty. Check the radiator for movement whenever you clean it. A common cause of looseness is perished rubber mountings (part no 171 121 276 D). These are four thick rubber washers on the locating lugs on each corner of the radiator. They are cheap and are readily available from the usual Australian suppliers, GoWesty or Van Café.
The plastic tanks are crimped on to the alloy core and sealed with a long, thin "O' ring, but the crimps are robust and the Behr radiators are well made.
Failure and/or leakage of the dual speed fan thermo-switch, (fitted to the back of the radiator bear the fan), can cause a problem. (P/N 251 959 481 K) but they are small and cheap enough to carry as a spare part. Don't forget the 22mm/29mm sealing washer, (P/N N 043 808 3). You can check the operation of the switch with a laser thermometer - the fan should cut in at around 87 C. and the second speed at 93 C., and cut out at 76 C. and 82 C. respectively.
Vans fitted with aircon have a fan resistor (P/N 251 971 284 H) fitted behind the passenger's headlight assembly which sometimes plays up, so that the radiator fan does not work when it should. The Van Café website states that "you can check it by unplugging the connector at the fan switch on the radiator. Connect the two outer poles and the high speed fan will come on. Connect the center pole to each of the outer poles (one at a time) and the low speed should come on in one of those pairings (nothing will happen in the other pairing). If the fan does operate as described with these tests, then barring a broken wire between the units, this resistor unit is bad. If the fan did not come on as described in these tests, then you must dig deeper."
Another potential for failure is cross-threading or stripping of the bleed screw. It is an M8x12 bolt (P/N N 010 237 6) with sealing washer (823 711 815). These are pesky to fit and easy to drop, so always carry a spare, and fit it with care.
Another cause of overheating is due to the deterioration of the cardboard baffles surrounding the radiator on the bottom and both sides, (P/Nos. 251 121 282 A, 251 121 282 A, and 251 121 283 B). GoWesty sells a superior thermoplastic replacement kit for less than $40.
Inefficiency and potential vibration damage can also be caused by the absence of the top and bottom gaskets, (P/N 431 819 225), which are often missing. Perhaps they have disintegrated, or been left off by lazy mechanics. I've never seen one, but the Ekta catalogue describes them as 1360 mm long strips. I presume that one strip cut in half would serve top and bottom. They are sandwiched in between the top and bottom radiator mounts. If anyone has seen a pair, perhaps they could post a description so we can make something to fit.
When I get round to fitting the new radiator, stainless steel pipes, junctions, reservoir and silicone hose kit I intend to modify the top radiator bracket to make room for an improved bleed valve. I will keep the group posted.
Roger B