How is a Snowmobile Engine Cooled? [+Maintenance Guide]


Snowmobile engines are cooled with air or liquid depending on the model. The liquid-cooled snowmobiles are much more common today. They feature a more complex cooling system that contains liquid (coolant) to keep the engine cool. Surprisingly, you can still find fan-cooled snowmobiles on the market, which simply use a fan to keep their engines cool.

Although both systems do a good job, they tend to overheat under certain conditions.

In this post, we will discuss these cooling systems. Beyond the basics, you can read about how to maintain these systems, so you can avoid overheating your sled.

If you want to compare liquid-cooled and fan-cooled sleds head-to-head, don’t miss our detailed comparison post!

What is a Liquid Cooled Snowmobile?

Simply put, liquid-cooled snowmobiles are powered with liquid-cooled engines. It’s safe to say that the majority of the new snowmobiles already come manufactured with these power sources. In the past, fan-cooled snowmobiles were much more common. But as engine performance has increased, the use of a more efficient cooling system became inevitable.

As an example, the first liquid-cooled Ski-Doo hit the market in 1976. Two years later, the manufacturer was already offering three different liquid-cooled power sources.

In 1993, more than half of Ski-Doos were manufactured with liquid-cooled Rotax engines.

Today, although fan-cooled snowmobile engines are still available, they are mainly found in entry-level and utility sleds.

There are many advantages of liquid-cooled snowmobiles, but the biggest is arguably their higher performance and efficiency.

The tolerances of their engines can be tighter, so they offer higher compression, more horsepower, and torque. The general rule is that a liquid-cooled snowmobile engine can always produce near double the power for the same engine displacement as a fan-cooled model.

What’s more, the engines of liquid-cooled sleds run at a consistent temp thanks to the thermostat. It results in a longer engine life and better fuel consumption.

Moreover, liquid-cooled snowmobile engines generate less noise and are also less likely to overheat without warning.

Are you wondering how a liquid-cooled snowmobile engine works? Keep reading!

How Does a Liquid-Cooled Snowmobile Work?

Liquid-cooled snowmobile engines work much like a car engines. They have some key parts such as the heat exchanger, the coolant, coolant bottle, thermostat, and water pump. The pump propels the coolant through the engine to transfer the heat to the heat exchanger. The temperature of the coolant decreases as it flows through the heat exchanger. Finally, the cooled liquid is propelled back into the engine to attract more heat from it.

As this circle is repeats all the time, the coolant can continuously transfer the heat from the engine. The thermostat controls the whole system via the water pump. The faster the coolant flows, the more heat it attracts from the engine.

Although they work in the same way, there is a main difference between car and snowmobile liquid-cooling systems.

While cars feature radiators, snowmobiles are typically equipped with heat exchangers. What is the difference?

The radiator in cars transfers the heat to the air while snowmobile heat exchangers are cooled with snow and ice. This means snowmobiles transfer the heat to the snow and ice, not the air!

If you check your car, you can see that the radiator is mounted in front of the engine. This is because it’s cooled by the incoming air from driving. Cars also feature a fan, which is located in front of the radiator. This fan makes the system more efficient as is turns on when the temperature of the coolant becomes too high.

Unlike car radiators, you can find the snowmobile’s heat exchanger in the tunnel.

This is because heat exchangers are not cooled by air but with snow and ice. While the track is spinning, it’s constantly throwing ice, snow, and water onto the heat exchanger to keep it cool.

This is why so many liquid-cooled snowmobiles overheat in shallow-snow conditions or on hard-packed surfaces. However, an ice scratcher solves the problem in many cases, and a studded track can also help a little.

What is a Fan-Cooled Snowmobile?

Fan-cooled snowmobiles, as the name suggests, are powered with a fan-cooled engine. These sleds are often overlooked and considered entry-level models. Although they are less efficient and offer lower performance, they have some advantages over liquid-cooled sleds. They not only require less maintenance, but they are also easier to work on. What’s more, fan-cooled sleds are usually more affordable and lighter compared to liquid-cooled models.

One of the main advantages of fan-cooled sleds is that they don’t overheat on ice or low-snow conditions. This means you can expect longer seasons on them!

Moreover, you can ride fan-cooled snowmobiles at very low speeds or can leave the engine idling without any overheating issues. These qualities make fan-cooled sleds good utility machines.

Another nice feature is that you can place your shields or goggles on the warm air that the engine blows out.

How Does a Fan-Cooled Snowmobile Work?

Fan-cooled snowmobile engines work in the same way as older ATV engines. Fan-cooled snowmobile engines have many little fins to pull the heat away. They also have a large fan that is stuck to the side of the engine. The role of this fan is to force cool air over the fins, which is how it dissipates the engine heat.

This fan is typically driven by the engine with a fan belt, but on some models it’s mounted directly to the crankshaft.

It’s good to know that snowmobile fan belts are prone to squeal if the tension is not adequate. Thus, these sleds required= more attention as their fan belt needs to be adjusted occasionally.

If you want to check how to set the tension on a snowmobile fan belt, don’t miss this tutorial video:

As you can see, a fan-cooled snowmobile doesn’t require any fluids. This means they are less prone to failure and are also easier to maintain!

Liquid-Cooled Snowmobile Engine Maintenance

Unlike fan-cooled sleds, the cooling system of liquid-cooled snowmobiles requires more attention and periodic maintenance.

Let’s see what the most important maintenance steps are on this system!

How do You Fill Up the Coolant on a Snowmobile?

Checking the coolant level on liquid-cooled snowmobiles is very important. If you operate your sled with an insufficient level of coolant, it can result in overheating or engine damage. To avoid these issues, always maintain the coolant level based on the manufacturer’s recommendation.

As cooling systems vary from one model to the next, it’s recommended that you read your sled’s manual for the exact steps and maintenance schedule. But as a rule of thumb, you can’t go wrong if you check the coolant level before every ride!

Liquid-cooled snowmobiles typically feature a coolant reservoir, which is also called a coolant bottle/tank or overflow tank.

All of these terms refer to the same part, a plastic bottle that is closed with a pressure can and some connecting hoses. You can find this bottle under the side panel or the hood depending on the model.

How do you fill up snowmobile coolant? You can typically find a “FULL COLD” or “ENGINE COLD” mark on the bottle. Make sure the coolant is at this level mark when the engine is cold. If not, you have to fill up the coolant as follows:

  1. Turn off the engine.
  2. Wait until the coolant cools down completely.
  3. Open the side panel/hood and locate the coolant bottle.
  4. Check the coolant level.
  5. Add/remove coolant as needed.

Check the Coolant Temperature

Beyond its level, you may want to keep your eyes on the temperature of the coolant during your rides. For your convenience, most snowmobiles feature a temperature gauge, which is also known as a “snowmobile coolant temp gauge.”

On newer sleds, this unit is integrated into the LCD screen of course.

This gauge has a very important role as it indicates the temperature of the coolant. It typically features a needle that moves up to the “normal range” as the sled’s engine warms.

The needle should stay in this range all the time. If you notice that it moves up into the “overheat range” you have to immediately reduce your speed or even turn off the engine.

Another trick is to ride the sled into the loose snow and spin the track to cool down the heat exchanger.

How do You Drain Coolant from a Snowmobile?

If you want to replace the coolant on a sled, you have to first drain the old liquid from the system.

You can easily drain the coolant from a snowmobile with a shop vac or a suction pump. Just mount a hose to the shop vac with duct tape, or attach it to the pump and suck out the coolant. Beware that although you can extract most of the coolant this way, some may still remain in the hoses. If you want to drain all liquids, remove the lower coolant hose in the engine as the last step.

But be prepared that it’s messy work as you probably won’t be able to catch all the spilled liquid. If you want to drain as much coolant as possible, don’t forget to jack up the rear bumper of the sled.

Here’s a video that shows how to drain coolant from a snowmobile.

How do You Get Air Out of Snowmobile Cooling System?

You can get the air out of your sled’s cooling system if you follow these simple steps:

  1. Open the side panel/hood and locate the coolant bottle.
  2. Jack up the front of the sled.
  3. Fill the coolant bottle to the mark.
  4. Loosen the air bleed screw located on the coolant bottle. (If your sled doesn’t feature this screw, just remove the cap.)
  5. Then, install the cap but just to the first lock. This means don’t tighten it to the fully seated location.
  6. Apply the parking brake.
  7. Turn on the engine and let it run at idle for a couple of minutes.
  8. The bleed screw should be loosened occasionally to remove the air. Use a rag or a towel to catch any leaking coolant.
  9. Once a steady stream of liquid starts to flow from the bleeder, tighten its screw immediately.
  10. Stop the engine and allow it to cool.
  11. Fill the coolant again to the mark.
  12. Reinstall the bottle cap.
  13. Level the sled and reinstall the hood/side panel.

This method is can be used on the majority of sleds, but before you proceed, make sure you check your sled’s manual. When you read it don’t forget that this procedure is known as “bleeding snowmobile cooling system.”

Can You Use Car Coolant in a Snowmobile?

Using car coolant or regular antifreeze in a snowmobile is not recommended. Best practice is that you always use the OEM snowmobile coolant that is described in the sled’s manual. This is because using the wrong coolant can damage the pump, which can lead to many major issues. A broken pump can leave the engine without cooling, which may end in a seized engine!

Let’s face it, snowmobiling an expensive sport. If you spend many hundreds (or even thousands!) of dollars on your sled, it doesn’t make sense to save a couple of bucks on the coolant!

Most manufacturers recommend using a 50/50 mixture of distilled water and ethylene-glycol as coolant. Keep in mind that straight antifreeze can gel at cold temps, therefore, water should always be added.

It’s also important that you never use tap water over distilled water, as minerals can cause issues and deposits in the system.

Be careful as some snowmobile coolants are sold premixed, so you don’t have to add any water to it.

On the other hand, straight antifreeze typically requires distilled water. Finally, it depends on what you buy, so always read the instructions on the bottle carefully!

Conclusion – How is a Snowmobile Engine Cooled?

Snowmobile engines are cooled with liquid (coolant) or air depending on the model. In the past, all snowmobiles were manufactured with fan-cooled engines. But as their performance increased, a more efficient cooling system became necessary. That’s why the majority of new sleds come with liquid-cooled engines.

As the takeaway, we’ve gathered the frequently asked question on snowmobile cooling systems:

What is a liquid-cooled snowmobile? A snowmobile that is powered with a liquid-cooled engine.

How does a liquid-cooled snowmobile work? The coolant attracts the heat from the engine and transfers it to the heat exchanger. The track throws snow onto the heat exchanger, cooling down the coolant in this way.

What is a fan-cooled snowmobile? A snowmobile that is powered with a fan-cooled engine.

How does a fan-cooled snowmobile work? An engine-propelled fan blows cool air onto the engine.

How do you fill up snowmobile coolant? Fill the coolant up to the mark on the coolant bottle.

How do you flush a snowmobile coolant system? With a hose attached to the shop vac or a manual suction pump.

How do you get air out of snowmobile cooling system? With the bleeding screw on the coolant bottle.

Can you use regular antifreeze in a snowmobile? No, always use OEM snowmobile coolants, which are specially formulated for snowmobile engines.

As the final word don’t forget to check the manual before you service your snowmobile’s cooling system!

References:

https://snowgoer.com/snowmobile-features/fan-cooled-shootout/2704/

https://www.autorepairs-richmond.com/blog/cooling-system-parts-descriptions.php

https://www.snowest.com/2008/09/the-heart-of-snowmobiling

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