Fan-cooled vs. Liquid-cooled Snowmobile For Ice Fishing

You know how important a healthy cooling system is if you’ve been unlucky enough to be stuck on the road as your truck boiled over. Your snowmobile’s cooling system is just as important when ice fishing or sledding. Today, we’re looking at the pros and cons of water-cooled vs fan-cooled snowmobiles.

Why Snowmobiles Need Cooling Systems?

Even Though you use your snowmobile in low or freezing temperatures, basic physics says it will overheat without a cooling method. Think of it like this, your computer needs a fan to stay cool enough to keep running, and it’s not even burning gasoline-like your snowmobile.

Snowmobiles use 2-stroke or 4-stroke gasoline-powered engines. 2-stroke engines produce more torque at high RPMs, whereas 4-stroke engines generate more torque at low RPMs.

2-stroke engines are more popular, possibly because they are easier to maintain and have fewer parts. 2-stroke engines use a gas oil mix. Ratios may vary depending on the age and model of the engine, but  50-1 is a good starting point.

Water-cooled and fan-cooled are the two types of cooling systems used in both 2-stroke and 4-stroke engines.

Fan-Cooled Engines

Remember your lawnmower, it probably used a single-cylinder engine. The cylinder head had many fins around it. These fins increase surface area allowing air to flow over them, helping quickly dissipate heat.

That’s a basic air-cooled engine. A fan-cooled snowmobile engine takes this design a step further. The cylinder heads have the same type of fins to catch airflow, but because of engine size, the fins alone can’t bleed off heat fast enough to cool the engine quickly enough.

The fix is to add a fan to the engine, increasing airflow to achieve proper cooling. The Polaris Voyageur 550 is a good example of a fan-cooled snow machine.

Because of their simpler design, Fan Cooled models are lighter, more easily maintained, and typically less expensive.

Liquid-Cooled Engines

The typical liquid-cooled snowmobiles use dual or single carburetors and displace between 300-500 cc developing horsepower of 150 per liter. At this output, higher liquid cooling is necessary.

A liquid-cooled snowmobile cooling system resembles that of other liquid-cooled, internal combustion engines comprising some or all of the following parts:

• Splash heat exchangers – all snowmobiles use heat exchangers for cooling. They’re a small device made of a tube and fin system similar to a radiator.
  • Because of the high efficiency of splash heat exchangers, not all snowmobiles use radiators.
  • Locations vary depending on the manufacturer. Common locations are in the tunnel where tracks throw snow on them.
  • Under the running boards is another common placement where the skis throw snow onto the heat exchangers.
  • High altitudes can adversely affect heat exchanger performance.
• Radiator – Your sled’s radiator is only about 100 sq inches. Often made of aluminum or brass with corrugated fins and tubes with coolant flowing through them.
  • Airflow over the fins cools liquid passing through radiator tubes. Being under the cowl reduces airflow, making the radiator alone not sufficient to cool the engine
  • A pressurized cap is used to keep pressure on the cooling system.
• Water pump – This is the heart of your engine as it pushes the coolant through your cooling system. It is typically belt-driven.
• Thermostat – is a temperature-sensitive sensor/valve. When the engine is hot enough, the thermostat opens and allows coolant to pass through the system.
• Coolant reservoir – The reservoir holds the coolant for your engine. The expansion tank receives hot coolant as it expands into the system.
• Other parts of the cooling system are hoses, sensors, and gaskets.

It’s true that a liquid-cooled engine is more powerful and quiet. But as the parts list alone reveals, a liquid-cooled system is far more complex and requires regular hands-on care or repairs.

In addition, Radiator snow splash heat exchanger system = 5-10% of sled cost and weight about 4%.

A Few Words on Coolants

It’s important to note that liquid does not mean water-cooled. Just like your car, your snowmobile’s coolant is most often a 50-50 mix of water with ethylene glycol or propylene glycol.

In its strictest sense, antifreeze is the Ethylene glycol or Propylene glycol you buy unmixed with water. Coolant is the 50-50 mixture you add to your cooling system. It works by lowering the freezing point to -30 degrees Fahrenheit and raising the boiling point of your coolant to 275 degrees.

Antifreeze also provides some lubrication for cooling system parts and has anticorrosive properties as well. Whether you choose premixed or mix your own, it’s good to remember that.

Ethylene glycol has a higher boiling point and a lower freezing point, while propylene glycol has lower toxicity.

Cooling Ranges

Maximum cooling occurs when you run your snowmobile full tilt in deep snow. Snow channeled into the tunnel, where the tracks throw it onto the heat exchanger. Snow covering the surface melts and cools liquid flowing through the heat exchanger.

The downside to this design is that liquid-cooled snowmobiles have a tendency to overheat in low snow conditions like those often encountered on an icy lake.  Overheating possibilities may be reduced by choosing a snowmobile with a radiator as part of its cooling system.

Minimum cooling – and increased potential to overheat occurs if your snowmobile idles too long.

At idle, the water pump is running slower, airflow across the radiator is zero and no snow is hitting your heat exchangers.

However, drive belt drag remains on the engine, and pistons continue firing and producing heat. Reduced coolant flow equals questionable engine cooling.

Liquid-cooled sleds are easier to start cold than fan-cooled, belt-driven, axial flow fans.

Side by Side: Fan-Cooled VS Water-Cooled

1) Common Uses of fan and liquid-cooled snowmobiles

Fan-cooled

• Used for ice fishing because of low snow or icy conditions,
• lightweight makes them good for young or smaller riders.
• Mountain riding.
• Recreational use and trail riding in warmer times with less snow.
• Can haul light freight.

Liquid-cooled

• Deep snow conditions.
• Recreational use on unbroken trails in fields, wooded areas, and mountains. One or two riders are okay.
• The more powerful engines are good for racing.
• Freight.

2) How do they work?

Fan-cooled

• The beauty of a fan-cooled sled is its simplicity. Airflow cools a 2-stroke engine.
• Air tunnels on the cowl and body of the sled funnel air across cooling fins covering the engine’s cylinder heads.
• A system of fans forcing air over the engine provides most cooling.
• Liquid-cooled

Coolant flowing

•  Through the water jackets on the cylinder heads.
•  Cools larger liquid-cooled engines. The primary cooling comes from snow melting on a system of heat exchangers. As the coolant passes through a network of tubes in the heat exchanger, it’s cooled by melting snow.
• So liquid-cooled sleds are less efficient in low, or hard-packed snow conditions or on icy lakes.
• Some models add a radiator that cools using airflow.
• A water pump keeps coolant circulating through the system.
• A thermostat allows or stops coolant flow as needed.

3) Affordability

Fan Cooled

• The simplicity of design makes them cheaper to buy.
• Fewer maintenance needs make them cheaper to own and operate.

Liquid-cooled

• The complex design makes them more expensive to buy.
• More expensive to operate. Coolants need to be drained, belts need to be maintained.
• Complex design means there are more parts to repair or replace.

4) Safety 

Fan-cooled

• Safety concerns for fan-cooled sleds are really limited to common sense riding and handling guidelines
• Keeping clear of moving parts such as tracks or fans.
• Exercise caution when working near hot engines or exhaust parts.

Liquid-cooled

• A liquid-cooled snowmobile has a pressurized cooling system filled with scalding hot liquids. To avoid burns, exercise caution when opening a pressurized system, coolant reservoir, or overflow tank, and when servicing areas near hoses.

General safety

• When riding in the mountains or fishing a frozen mountain lake, be aware of potential avalanche conditions.
• For a complete discussion of snowmobile safety guidelines, visit the ISMA website.

So, are fan-cooled or liquid-cooled snowmobiles better for ice fishing? Liquid-cooled sleds like the Arctic Cat Blast M 4000  are better for general use, but liquid-cooled sleds need sufficient snow to cool properly.

Because they rely on air for cooling, the conditions found on frozen windswept lakes with icy surfaces, minimal snow cover, or hard-packed, crystallized snow, make perfect conditions for fan-cooled sleds. All this makes fan-cooled sleds like the Polaris Voyageur 550  the best choice for ice fishing.

Maybe you’re saying, “Yea, but I already have a liquid-cooled snowmobile.” Relax, not only is it good for everything else, but you can still use it for ice fishing, just pay attention to snow conditions and engine temperature.