3 Steps To Winterize A Boat Engine


You might not realize just how devastating a quick freeze can be, but trust me when I tell you that winter can cost an unprepared boat owner a repair bill in the tens of thousands. Please winterize your boat engine!

Here is my own tale of terror: Being a California native, I didn't think much of moving to Michigan. We were going from saltwater to freshwater so I assumed not much preparation was needed. Little did I know that I needed to winterize my boat engine. It just wasn't something people in my sphere had ever talked about. 

I wasn't totally clueless, I knew there would be a freeze so I dry-docked my vessel. Little did I suspect that might have been the most expensive mistake of my life. Spring finally rolls around and I'm ready to hit the lake, but my boat wasn't. She was in literal shambles due to my carelessness.

$5,000 dollars went down the drain due to a cracked manifold just because I didn't know how to simply winterize a boat engine. Don't end up like me. Here are three steps that you can use to winterize a boat engine and ensure that you steer clear of potential disaster.

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Antifreeze, A Friend Indeed

Propylene glycol antifreeze is probably the easiest fix around to avoid costly engine repair. You can also use ethylene glycol but it is quite toxic. Think of the planet and please go for the propene-based antifreeze. Thanks.

If you're going to winterize a boat you'll need around a five gallon bucket and two gallons of antifreeze to protect your engine and all related plumbing. Why a five gallon bucket for two gallons of antifreeze? Simply because the antifreeze needs to be diluted with water.

How diluted the solution needs to be depends on your locale and the brand of antifreeze, but generally a 50/50 combination can get the job done just fine. If your antifreeze is dirty, you must change it completely.

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Adding new antifreeze to the old stuff will obviously result in a ratio higher than the magic 50% and at lower temperatures the antifreeze could gel together which defeats the purpose. 100% antifreeze will gel at just -8 F.

Another alternative is to dry your engine completely, but that can quickly become a battle of wills. I vastly prefer simply running some antifreeze through the engine for a while to opening the engine and searching for wayward water.

If you run your boat in salt water you are going to make sure you run some salt removing solution through your engine.  We are biased but recommend our De-Salt solution.

Ensure that you run your engine long enough for the antifreeze to reach every part of your cooling system, not just the parts upstream and you'll be ready for the next step on our journey of how to winterize a boat engine.

You also will need a flushing kit to run it through your engine.  We offer a great engine flush kit as well.  

If you want to see a video of the whole video of how this is done you can click here to see a video about flushing and de-salting your boat engine.

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Go Fog Yourself

If you have a gasoline engine, you will need to fog it in order to winterize your boat engine. You'll need engine fogging fluid of course, but you should also come prepared with some plastic sheeting and duct tape. Once the antifreeze has been run entirely through your engine, prepare the fogging fluid.

During around the last 10 seconds of engine operation you'll want to spray your fogging fluid directly into the flame arrester on the carburetor. Wrap the flame arrester with duct tape and add some plastic wrap once it has cooled down decently. This will allow the fog to stay where it needs to be.

This process will prevent corrosion on your engine parts while the boat isn't in operation. While it might not have as much negative effect as skipping out on the antifreeze, your engine is not something that you want to roll the dice on.

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At the end of the fogging process your engine might end up stalling, and that is completely alright. Keep the plastic sheeting in place during storage, but remind yourself with a note of some kind so you don't ponder why your engine seems dead come springtime.

There is really no reason not to fog the engine while you winterize a boat engine. No matter what, just fog your engine. It could hardly be any cheaper. You can pick this fluid up for a little over ten dollars and it just might save your bacon.

Fogging your boat's engine has never been easier, or cheaper!

Storage Wars

So once your engine is full of fogger and antifreeze, the question remains of whether to leave your vessel in the water or dry-dock. I'll spoil the surprise right off the bat and reveal that you should probably dry-dock if you can afford it.

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If you can snag an indoor dry-dock you'll be in the best shape possible, but it can be pricey and may or may not be available in your area. Regardless, indoors is better than outdoors but you might have to make do with what you have access to.

Storing your boat out of water can actually make an unpredictable cold snap even worse if you haven't taken time to winterize your boat engine. Water cools much slower than air, so ensure that you're ready for a freeze before you're out of the water.

Keeping your vessel in the water isn't a much better prospect to be honest. One of the biggest troubles is hull blistering. Frozen water can create cracks in your resin and allow said water inside once it freezes. Now that's a costly fix.

Either way you want to make sure you keep moisture down to a minimal.  We recommend you use boat dehumidifiers to reduce the moisture under your cover.  We offer a refillable boat dehumidifier as well as dehumidifier bags and disposable dehumidifier buckets.  

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Winterize A Boat Engine Conclusion

We might cover how to prepare the rest of your boat for winterization in another article, but this should be enough to winterize a boat engine for starters. It is certainly leagues ahead of where I was when making my tragic mistake.

I hope I've managed to stress how important and how absurdly easy it is to winterize a boat engine. It is amazing how many claims are made for improper winterizing of a boat. While this guide is not a be-all end-all, it should get you started on the right track!

Keeping your boat running is only half the battle. Keep your boat looking great on the outside as well as the inside with The Better Boat's line of premium boat care products!