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This is the last of three articles on the TR's cooling system and should be read in conjunction with the previously published parts one and two.
If you are going to regularly drive your TR today then there are some improvements that you can make. What was acceptable in the1950's becomes very suspect in the 2000's. The ambient temperatures in the cities are higher today and not just because of global warming but because of the greater expanses of concrete, bitumen, and tall buildings.
The average speed in traffic is lower and we spend more time stationary at the traffic lights. On the open road, we are able to maintain higher average speeds for much longer. Today when I drive out of town, I jump on the freeway and sit on 75MPH for some hour's straight and in ambient up to105 ° F (40 ° C). As a result much more stress is placed on all vehicle components today.
Radiator Apart from keeping it clean and not fitting a crank handle hole when re-coring, there is not much you can do here. Modern radiators and/or larger radiators can be fitted but unless you are competing with your car, it is not really necessary and as such not covered here.
Coolant As discussed before, a good quality coolant should be used with a 33% mix of anti freeze/anti boil and a good corrosion inhibitor package. Remember to change the coolant as per the manufacturers recommendations, that is assuming you can keep it in the engine for that long.
Water Pump Again not much you can do here. I know of one TR3 owner that is fitting one of the new electric water pump kits. This seems to be the ideal but beyond what is normally required or would be undertaken by most TR owners.
Thermostat The problems with the commonly available thermostats has been covered so apart from looking at fitting a restriction in the by pass line, not much can be done here. Do not be tempted to run without it. It is important that the engine is able to reach its optimum temperature.
Temp Gauge The unit fitted is fine.
Hoses & Pipe Units fitted are fine.
Engine Passages Just make sure the system is kept clean.
Radiator Cap The function of the cap is to maintain the desired pressure in the cooling system. In doing so it dumps excess coolant. Modern systems catch this excess and return it to the radiator when the engine cools down. Fitment of a similar system to your TR is a relatively simple and worthwhile project. There are two methods, both being used to day and each with their advantages and disadvantages.
Remote Top Tank . In this system we fit a remote coolant reservoir and connect it to the radiator. This Reservoir runs under the same pressure as the cooling system. A suitable Reservoir (eg Mini Minor) is mounted (normally on the RH inner guard) level with the top tank. The overflow pipe on the radiator filler neck is then connected to the inlet pipe on the remote tank. A blanking cap is fitted to the radiator in lieu of the standard cap and a conventional radiator cap fitted to the remote tank. Remember that the whole system will be under pressure so be sure to use suitable hose and clamps.
What we have done is simply add coolant volume and move the radiator cap from the radiator to the remote reservoir. In operation the radiator is filled and the remote reservoir is only partially filled. This provides space for the excess coolant to be stored so that it can return to the radiator when the engine cools.
Advantages:
Disadvantages:
Coolant Recovery Tank . With this system we still add a remote tank but it is not under pressure. A suitable reservoir (eg Mid 80's Mazda323) is fitted under the bonnet (eg RH side front apron cross brace). The overflow from the radiator is connected to the inlet of the remote reservoir.
The standard radiator cap is replaced with one suitable for a recovery system. These caps are the same as the standard ones except they have a seal at the top to prevent any fluid loss around the cap and directs all excess coolant out the overflow pipe.
The recovery tanks are normally translucent and marked with Min/Max levels. As the coolant heats and expands, the excess coolant dumped by the radiator cap is captured by the Reservoir. The cooling engine then draws this fluid back in from the Reservoir.
Advantages:
Disadvantages:
Another worthwhile mod is to have the original radiator filler neck changed for modern short neck filler if the radiator is ever removed. This allows the readily available caps to be used. This is relatively inexpensive, and overcomes the only real disadvantage of the coolant recovery system.
Cooling airway The TR2/3 is OK as is the TR3A providing the baffle is fitted correctly.
Fan As this is the weak link in the system, it has the greatest potential for improvement. There are two approaches, upgrade the fan itself or remove it and fit an electric one.
Upgrade. The original 4 blade fan can be changed for a more efficient one but if this is contemplated then it must be remembered that it is a crank mounted unit. Ie bolted direct to the crank, albeit through an adaptor. The problem with crank mounted fans, and one you may have experienced, is one of blade failure. Torsional vibrations are transmitted from the crank to the fan and lead to cracking and failure.
To reduce this in the TR, the fan is isolated from the crank with rubber bushes. This also tends to allow the fan to act as a basic harmonic balancer. Any fan replacement must also incorporate some form of torsional isolation. A suitable fan is one from the early Triumph 2000 sedan. It is a 6 blade steel and aluminium unit that mounts the same as the TR and is directly interchangeable. This fan works well but there are others. Just remember those torsionals.
Electric. Here again we have two approaches. Fit the fan in front or behind the radiator?
Front. This is the simplest method and allows a wide variety of fans to be used. A suitable fan is mounted in front of the radiator and connected to the cars electrical system.
Advantages:
Disadvantages
A fully shrouded fan is the most efficient but offers even more restriction at speed.
Rear. This involves fitting a fan at the rear of the radiator. Mounting is more difficult due to the restricted space available and this restricts the number of fans that can be used. A fully shrouded unit is best as it prevents any air recirculation.
Advantages
Disadvantages
Overall, although it's a little harder, the rear-mounted option is best. Both work well in town but the rear is much better at speed.
Electric Fan Controllers.
A switch could simply activate the fan but it is desirable to automatically control the fan so that it does not run unless required. Again there are options. The common type of controller is one where a probe is inserted in the coolant flow via the top radiator hose. This is connected to an adjustable temperature switch by a capillary tube. This in turn activates a relay to supply power to the fan. This is a clumsy looking system and easily damaged.
An alternative system is a fully electronic unit that utilises a small contact probe that simply pushes into the radiator fins below the inlet hose. This is connected to a small electronic module that incorporates both the temperature-controlled switch and the relay.
Regardless of the system used, the cut in temp should be about 8 ° F(5 ° C) above the thermostat opening temperature.
Oil Coolers.
Not a mandatory item but one that provides distinct advantages to people who do what TR's do best, cruise at speed on the open road. The engine oil plays a crucial roll in cooling various components within the engine. Normally the oil is cooled by airflow over the block, sump, head, rocker cover, etc as well as contact with the fluid cooled surfaces. The engine oil will run hotter than the coolant.
Back when the TR was king (still is) this was adequate unless you were undertaking competition. Today, we can all jump in our car and cruise at speed for some time without slowing. The standard TR was not designed for that. We can upgrade the coolant system but what of the oil. To perform all its functions as designed, the oil should run within a specified temperature range. Operation of the engine gets the oil up to temperature but we need some means of controlling the upper limit. This is where an oil cooler can help.
There are a number of adaptors available to direct the oil, after the filter, to an oil cooler before entering the main oil gallery. A good one is available that forms part of an adaptor that converts the lube filter to a spin on type and incorporates an oil thermostat. This thermostat is set at 176 ° F(80 ° C).
If utilising an oil cooler then it is strongly recommended that a thermostat be incorporated in the system. This controls the temperature of the oil much the same as the cooling system thermostat. It is important that, like the coolant, the oil is allowed to reach its optimum temperature.
I hope these three articles have been of some interest and benefit and if you have any questions or can add to this then I would be most happy to hear from you.
Since this article was written, there have been some new products come available or known to the writer. Two are listed below.
Water Pump.
There is now available an uprated water pump. I have no experience or knowledge of its benefits.
A recent release from Moss Europe (Triumph World Apr/May 2005) quotes “The uprated water pump for example, comes with a 6 bladed impeller that should virtually double the flow of coolant through the system.”
A word of caution about high flow water pumps. A doubling of the pumps potential flow will not give a doubling of engine cooling. There may be a gain but as in most systems, all components are interrelated. Increasing the flow through the radiator means that the coolant spends less time in the radiator and hence less heat will be transferred to each litre. Also the increase in flow will cause a greater pressure drop across the thermostat, radiator, and coolant passages giving a drop in the potential flow. There will be an overall increase in heat transfer due to a higher flow but how much is dependent the systems capacity to utilise this potential flow.
It is important to remember that the original TR impellor did not change through to and including the TR6. It is also the same as the Triumph 2000 and 2500. These engines all have a higher output than the TR2,3,3A.
It is not being suggested that an uprated water pump is not worthwhile, just temper your expectations if that is the only change you make.
Radiator.
There is available, what is called a CT Core. This core is new technology and visually different to the standard core. It is also probably the biggest single improvement available for the TR cooling system.
Each cooling fin in the standard core is one piece and runs horizontally across the cooling tubes, locking them together. In the CT core, they run in a zig zag pattern vertically between the tubes. Radiator repairers have advised me that this change means that the cores life will be shortened, from 30 to 35 years to 20 to 25 years. Not a problem as I see it.
The big plus is the claimed 25% increase in efficiency. Unlike the uprated water pump, the gain is available regardless of the rest of the system. Any coolant pumped through the radiator will be subject to this gain. If the only mod made to the system (both air and coolant) is the addition of a CT core, then the net gain will be that of the radiator. A claimed 25% over the current heat transfer.
A CT core would allow the maximum benefit to be gained from an uprated water pump.
The CT core gets a big recommendation and should be seriously considered when having your TR radiator repaired or re-cored. The down side is that it is about 20% more expensive than the standard core. No gain without pain.