Water is the second most destructive contaminant that can invade your oil. Continue reading to find out:
- How to find out if you have water in your oil, even if you can’t see it.
- What is an acceptable amount of water in the oil
- How does the water get in the oil
- What do you do if you find water in the oil
- Why you should change your stern drive oil at the end of the season and not the beginning of the season
Most people will recognize if the oil is milky or cloudy that there is a problem. But most people do not know that a bearing can lose 75% of its life before you can even see the water in the gear oil.
If water get into your engine or gear box 3 things happen:
- Viscosity changes and film strength reduces lessening the ability to lubricate
- Corrosion occurs on gears and shafts which in turn causes bearings to wear faster
- Additive depletion Oil brakes down causing acid formation, varnish and sludge
How to find out if you have water in the oil.
The first thing to do is look at the oil. If it’s cloudy or milky you have water and you must get it out ASAP.
If you suspect water might be getting in or if you have a gear box under water (stern drive or outboard motor) you should check it frequently.
If you can’t see any cloudiness you can do what is called the “crackle test”. This is a test that factories have been doing for years and it is still a good field test even if you are getting regular oil testing done. It is usually done with specialized equipment but you can do it with your wife’s coffee maker. Or you can save your marriage by getting a used coffee maker at the local thrift store. The idea is to bring a heat plate up to a temperature about 220°F – 300°F. I checked my coffee maker and it comes in at about 240°F, perfect.
The type of coffee maker I’m talking about is the standard drip coffee maker with a burner on the bottom that heats up the usually glass coffee pot. The burner is usually controlled between a maximum temperature and minimum temperature.
Turn on the maker and wait until all the residual water is boiled out of the reservoir. You can hear it gurgle. When the gurgling stops, place a drop or 2 of the oil in question on the center of the plate. If nothing happens your oil is water free. If it crackles or you can see any bubble form you have water in the oil. It happens fast so you need to watch carefully (see the video).
Degrees of water contamination:
- 0.025% oil appears normal – bearing life can decrease by 50%
- 0.1% oil appears normal to the eye – bearing life can decrease by 75%
- Greater than 0.1% oil may appear cloudy or milky depending on temperatures and additives – bearing wear is substantial
How does water get in the oil
On some older models of stern drive, there was no vent or reservoir for makeup oil. Therefore when the oil gets hot pressure builds up inside the gearbox and if there is any weak seal, the pressurized air will leak out. Then when the gearbox cools down, a vacuum is created which the sucks air or water through the wear seal. If the weak seal is under water you get water in the oil. Many times it is the o ring on the drain plug that is under water.
Check all your seals regardless of the age of the boat. In fact the o ring on the drain plug should be changed whenever it is used.
If you start thinking about it you might figure out the best time to change your oil is whenever it gets contaminated. Check it often and check it before you put the boat up for any length of time.
Simple as that.