The amount of damage to your motor and drive from freezing will be more dependent on the amount of water in your motor and lower unit than on how much grease you used.
If your motor is a closed cooling unit
, which means that it has a heat exchanger and antifreeze, there is a good chance that the damage will be minimal if at all. On the other hand, if your motor is an open cooling system
, which means that it pumps sea or lake water through the motor, there is a good chance that you will have a cracked block, which will unfortunately be expensive to repair. You will know very quickly in the spring when you start up your motor.
If your drive was left in the trailered position
, there is a good chance that there will be water trapped in the lower gear case, and this could cause cracking in this area. If it was left down as the manufacturer recommends
, there is a good chance that most of the water will have drained out and you may be lucky and no damage will result.
Other problems that you may encounter are seized pistons from not fogging the cylinders. Rust will form on the walls above the cylinders and when you start up your motor, if it will even turn over, you could crack the rings and or score the cylinder walls. This will require an engine rebuild. In addition to fogging the cylinder walls with fogging oil. It’s also important to change the engine oil in the fall to remove contaminants and properly lubricate the lower end of your motor. Old engine oil contains contaminants, which when mixed with water from condensation, turns to acids, which attack the metal in your motor. Old gasoline in your carburetor turns to a varnish type sludge which can impede the performance of your engine. This is why the manufacturer tells you to use fogging oil in the carburetor and to run the motor until the reservoirs in the carburetor are dry, if possible.
It's also important to change the oil in you drive unit for the same reasons as above. Plus this is a good time to check if the oil is milky, indicating that you have a leak which is allowing water into your gear case. This is not good as it will cause overheating of the drive line and eventual wear or seizing, again requiring very expensive repairs.As to what you can do at this time to mitigate any further damage:
• First make sure that the drive is lowered.
• If you can, change the oil and inspect it for the presence of water. There is a small magnet attached to the lower plug. Inspect this for the presence of undue amounts of metal.
• If either of these conditions appear, you would be wise to consult a good marine mechanic.
• Remove the propeller, if you have not already done so and grease the shaft and hub.
• You can then reinstall the propeller or store it indoors until the spring. This a good way to prevent theft if your boat is stored outside.
• This is a good time to inspect the propeller and schedule repairs if you see any dings or other damage.
As far as the motor is concerned, most of the Mercury motors used with the Alpha drives were open cooling types, so I will assume that yours is as well. You probably won’t be able to tell if the block is cracked until the spring, because they can crack in many different places, including internally. If there are no obvious cracks, I would proceed as if there were none and do the following to salvage your motor:
• These motors have frost plugs and if there is water in your motor and you are lucky they may already have popped out to relieve the pressure.
• There are also stop cocks in the lower part of the block. Open these and leave them open.
• If you are able, suspend a 100 watt light bulb in the engine compartment. This will slowly start the melting process and allow some of the water to drain out of the stop cocks.
• Remove the sparkplugs and spray the inside of the cylinders with sprat type fogging oil.
• Do not try to turn over your motor or start it until the fogging oil has had a week or two to penetrate any rust and free up the piston rings. It will be difficult to change the motor oil until you are able to run your motor again.
• This will warm it up and reduce the viscosity so you can pump it out. When you do this, be sure to change your oil and fuel filters.
• If you can, add fuel stabilizer to your fuel tan and top it up with fresh gasoline.
Gasoline will deteriorate in the tank when left to sit for long periods of time and the temperature differences will also cause condensation to form, resulting in water in your fuel.
If this happens, your motor may not run very well, if at all in the spring and you may have to remove the fuel, clean out the lines and replace it with fresh fuel. The stabilizer and top up can help prevent this.
You will not be able to do much more until you can run your motor. At that time, change the oil and filters as soon as possible to eliminate further damage and do a thorough inspection and maintenance. Lack of proper maintenance of you motor and drive unit will shorten their life considerably. Compared to the cost of repair or replacement, maintenance is very cheap.
Hope this helps,