Many lawnmowers, string trimmers, leaf blowers and other lawn and garden equipment with small engines were inundated during the flooding from hurricanes Katrina and Rita. In many cases, that equipment can be salvaged. It is difficult and expensive to salvage more complicated equipment like cars, trucks and tractors because of issues with electronics, upholstery, etc., but small lawn and garden equipment is much simpler.
It is important to get your small engine dried out as soon as possible. The longer it sits in water (or water sits in it), the greater the risk of major damage. Cleaning and drying the engine immediately may allow you to save it. If the engine has been exposed to salt water, you should wash it with fresh water before drying it. Also, wash off any mud or trash before drying.
You should empty the gasoline tank and dispose of the diluted gasoline at a recycling station. It will be easiest to drain the fuel tank if you remove it first. If you have access to an air hose, blow out the gas tank to help dry it. If not, try to dry it with a small rag. Spraying a little WD-40 into the tank will help dry it.
You will need to drain the crankcase on 4-stroke engines. If water comes out with the oil, add some light oil, rock or shake the engine, then drain it again and repeat until no water comes out with the oil.
Remove the spark plug and drain out any water in the cylinder. Add a teaspoon or so of engine oil through the spark plug hole and then rotate the engine a few times while the plug is still out to coat the cylinder walls. If the engine is frozen, you may need professional help or may have to discard the engine. After turning the engine over with oil in the cylinder, install a new plug or carefully clean and regap the old plug if it is still in good shape. Install the spark plug using the correct torque.
You will need to replace the air filter and remove any water in the carburetor. If the engine has a fuel filter, replace it. Clean and drain the fuel lines before installing a new filter. If you have an air hose, blow out the fuel/air system before reassembly.
If the machine has a transmission case, check for water. If any water is present, drain the case, dry it and replace the gear oil.
If the engine has an electronic ignition module, that might have to be replaced also.
After thoroughly cleaning and drying everything, add clean engine oil and fresh gasoline, then try to start it. Running it will warm it up and help dry any spots you missed.
You just might be able to save your small engine!
The LSU AgCenter and the LSU College of Agriculture