The cooling system is a crucial part of your snowmobile’s engine. While older snowmobiles included both air cooled and liquid cooled models, modern snowmobiles are more commonly liquid cooled. The liquid engine cooling system is an extremely effective design, but requires periodic maintenance, including flushing out and replacing old coolant, to ensure proper continued operation. Dirty coolant and the buildup of acidity and rust can cause poor cooling system performance, and in extreme cases, catastrophic failure. In this article we’ll talk about how to flush a liquid cooled system on a snowmobile to ensure smooth operation.
Flushing and cleaning a dirty cooling system in your snowmobile is easy, and you can do it in your garage in under two to three hours. Difficulty and time required can vary depending on how much dirt and rust is built up inside the cooling system. Here is the list of everything you will need to flush your snowmobile’s cooling system properly.
- Chemical cleaner flush fluid. I recommend you to use this one. Prestone AS105-6PK
- Distilled water for cleaning the cooling system and mixing with antifreeze. Amazon Link
- Buckets or any other container to store the waste coolant. Amazon Link
- Ratchet socket set to open and close bolts. Amazon Link
- Philips head screw driver to remove any body panels or unscrew any clamps. Amazon Link
- Needle nose pliers for removing hose clamps. Amazon Link
- Funnel to add flush fluid/coolant into the snowmobile. Amazon Link
- Paper towels to clean any spills or drips while doing the job. Amazon Link
- Patience. This one is a very important tool to have and key to success. Unfortunately, Not Available on Amazon.
Before starting the flushing of your coolant system, you should understand how it works.
Snowmobile cooling works just like your truck or car. In snowmobiles, there are heat exchangers (instead of radiators). They are connected to water jackets (inside the engine) and a coolant reservoir via coolant hoses. In some snowmobiles, there is also a radiator at the front (usually in utility machines that do a lot of pulling and heavy duty work). All of those parts are filled with coolant, and need to be flushed. Heat exchangers are not mounted universally on all snowmobiles, so you have to look at your service manual or look on the internet to find the details about the heat exchanger on your snowmobile.
Caution: Flushing must be done when your snowmobile’s engine is relatively cool. Working on a hot engine can result in severe burns from the hot coolant that has been pressurized in the cooling system.
Step 1: Find the coolant reservoir on your snowmobile.
The coolant reservoir is a bottle that is connected to the cooling system (radiator or heat exchanger). Take the cleaner flush fluid and put it in your snowmobile’s coolant reservoir bottle up to the fill line. If the coolant is already up to the fill line, you can follow the second step to drain some coolant from the reservoir bottle and make a little room for the flush fluid.
After filling the flush fluid, ride your snowmobile for at least ten miles. This fluid will help loosen the rust/acidic build-up caused by old or not the right type of coolant and then flush (remove) it out of the cooling system. That is why this liquid or process is called a flush.
You can skip step one if the condition of your snowmobile’s cooling system is not too bad.
Step 2: Drain the old and dirty coolant and flush out all the acidic/rust build-ups.
Find the heat exchanger(s) in your snowmobile. Usually, it is mounted above the track. There might be more than one heat exchanger in your snowmobile. You will need to drain the dirty coolant into a bucket so you can dispose of it properly. The coolant is a toxic chemical and tastes sweet. Pets and children are more likely to taste it (or even drink) if it is in reach. To dispose of it, you should check your state law about the disposal of toxic and hazardous chemicals.
First, unplug the main-hose of the heat exchanger, using the needle nose pliers to remove hose clamps. This hose goes directly to the engine. Put this hose in the bucket/container. If your snowmobile has a radiator, then you can unplug the hose from it as well to drain the remaining coolant.
Also, some snowmobile models have coolant drain-holes capped off with a drain plug. These drain holes are on the underside of the heat exchanger(s) or the radiator. You can unscrew and use these drain holes for proper draining.
There is a valve with a cap that is used to fill the coolant in the cooling system. Opening the valve cap will normalize the air pressure and help drain out all the coolant. If you do not remove this cap, the coolant will have a hard time draining out of the cooling system.
The coolant in the reservoir bottle will not drain on its own. You can remove the reservoir bottle and empty it in the bucket. Or you can disconnect the hose coming out of the reservoir and drain the coolant out that way.
Step 3: Close the drain hole and re-fill with distilled water.
If you have used the drain hole, put back the drain plug, or if you have used the hose from the engine block to drain the coolant, then put that hose on and the hose clamp. Make sure it is on there securely, so no coolant leaks out. In snowmobiles, the heat exchangers and the engine block are usually at the same level. In this case, you will need to lift your snowmobile (at least 24 inches from the ground) from the front. This way, the air will not get trapped inside the cooling system and form small air-pockets.
Take distilled water and fill it in the cooling system. Fill the cooling system with the distilled water through the valve (the cap with a yellow or red sticker you opened before). Always use a funnel and pour it slowly to prevent any air pockets. Then fill the distilled water in the coolant reservoir. Remember to put the coolant a little more than the line in the reservoir bottle and put on the cap on it.
Step 4: Burp out the air bubbles so the water/cleaning fluid can do its magic.
It is important to burp out the air bubbles or air pockets from your snowmobile’s cooling system for the flushing process to work properly. You can remove air bubbles by squeezing the main-hose, going from the engine to the heat exchanger, and the second hose with the valve on it. This hose (with a valve) goes back to the heat exchanger. Squeeze both of these hoses until no air bubbles are coming out. You can also lift the snowmobile from the front so any air trapped inside will come out.
Step 5: Close the valve and start your snowmobile for 10 to 15 minutes.
Put the cap on the valve of the cooling system and make sure that it is tight. Start the engine of your snowmobile and let it run for about 10 to 15 minutes. The engine will heat up, and the distilled water will circulate through the cooling system. And it will dissolve any loose rust or debris that did not get removed the first time.
Step 6: Turn off the engine and drain the distilled water. And repeat.
Collect this water in a bucket and dispose of it according to your state laws. Repeat from step two to five until the drained water is clear and does not contain any loose particles or rust. At this point you have completely removed any rust or acidic build-ups from your snowmobile’s cooling system.
Step 7: Remove the reservoir and wash it.
To clean the coolant reservoir bottle, you can remove it from the snowmobile and wash it. You need to remove the hose coming from its bottom and drain it in a bucket or container and use lukewarm water to clean and remove any contaminants.
Step 8: Refill coolant into your snowmobile.
Now your snowmobile’s cooling system is clean and ready to be filled with the correct coolant. Always use the recommended antifreeze mixed with distilled water in a recommended ratio. There are also pre-mixed coolant options that take the guess work out of mixing. You can find mix ratio information in the service manual (typically it’s 50:50 or 60:40). Also, do not forget to bleed out the air bubbles out of the cooling system. I have written a complete guide (with pictures) about refilling a coolant and removing any trapped air bubbles in your snowmobile.
In the end…
Congratulations! Now that you have successfully flushed your cooling system, your snowmobile is going to perform at its best. Every snowmobile is different, and depending on your snowmobile’s model, some steps might vary for you. I have tried my best to explain each and everything thoroughly. If you still run into a problem or confusion of any sort, ask in the comments down below. Also, do not forget to check your state laws about how to dispose of coolant.