Cooling - "Another minor inconvenience..."
Dual Radiators
The cooling system in the car, when purchased, was pretty much stock. The exception to this was an additional radiator in the rear of the cabin (together with thermo fan) that had been plumbed into the heater circuit. Soon after acquiring the car, we removed this unit and gave it a good flush*, due to the lack of heat being radiated by it whilst the car was running. The flush helped marginally, however it became obvious that the run to the rear was simply too long to be driven by the heater circuit. As we didn't have a readily available electric water pump, the radiator got chucked to save weight. This was also to comply with a recent addition to the CAMS regs. that ruled out having large volumes of hot water inside the cabin.
* - It's much easier to use a combination of high-pressure air and water to loosen dirt inside a radiator core, than just water alone. In fact, you can buy a tool that does exactly this from some 4WD stores.
Water Pump
The first major modification to the cooling system was after the install of the quad-cam and involved an external bypass and a re-bladed water pump. This was brought on by the failure of the seals on the stock water pump impellor. Note that replacing the water pump is not a simple task in a quad-cam. It takes a good couple of hours to get the motor stripped down to a point where you can actually remove the pump. While we had the front apart we also replaced the timing belt; just to be sure...
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External Bypass
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The external bypass was installed at the same time as the water pump rebuild. The design simply moves the thermostat from the outlet side of the engine to the inlet, and runs a restrictor/bypass to force water flow past the thermostat. This effectively means that the cold water from the radiator is metered into the engine based on the water temperature inside the engine. This always struck me as being a far more logical way of doing things; rather than subjecting the engine to cold shocks every time the thermostat is opened. In hindsight, this system is probably more complicated than necessary, for this type of racing. It did however, give us the ability to monitor both the engine and radiator temperatures on separate gauges; which was a handy thing a numerous occasions. |
Oil Cooler
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The somewhat prone location of the
oil cooler in the Datsun, meant that
a bit more thought was put into the installation in the Commodore. The eventual
location is as shown. Note that any rocks/mud entering from the front of
the car (through the old indicator position) will hit the rear of the air box and
not the cooler. The air however, is forced up through the cooler, due to the
area under it being almost completely sealed. This design is very similar to
what you see in many engine air filter boxes.
At one stage, due to the close proximity of the cooler to the bonnet, we actually cut a ventilation hole in the bonnet (hoping to improve the cooling efficiency). Unfortunately, this had the opposite effect, with a notable rise in engine temperature, and so the cut-out was resealed. Obviously the air pressure on top of the bonnet is higher than that under the cooler, and so air-flow was actually decreased, not increased. |
Radiator Mesh
Suggested by a guy that runs speedway. The basic idea is to have a sprung mesh sitting in front of your radiator. The gravel/rocks will hit it and be deflected and mud will be shaken loose by the mesh's sprung motion. We certainly never had a problem with the radiator core after installing the mesh. Unfortunately it doesn't cope with muddy creek crossings, which tend to block the radiator regardless of what is in front of it. Only solution to this problem is to get the radiator out of the water/mud.
