How bad is it that I left my lawn mower outside in the rain?

Not if you do the right thing now. You have to make sure that no water is still in it before attempting to start it. The most likely place for water is in through the air intake, it is likely to fill the air filter and flow into the carburetor venturi (air intake). You need to drain and dry that, then remove the spark plug and turn it over. Make sure that no water is expelled from the cylinder and also that none has gone through into the sump. If the oil in the sump is whitish, it will need to be drained and replaced.

I wouldn’t worry about it. I do it all the time. They are designed so water falling down on them won’t get in them. As long as the gas cap and oil cap are on securely you should be fine. Usually the air intake has a cover and is on the side.

I would be concerned if it fell in a swimming pool. Shit, I hose ours down to clean it.

Silly billy

It might be electric! Is it?

Bad.

Not so bad. Was gas cap tight, so no water got in the tank. Was the spark plug cover (rubber thing) in place, if so, shouldn’t have hurt it at all. Forget about the carburetor they are usually under the fuel tank and would take a deluge to get ANY water in the air intake and sump (how the hell would rain water get in the sump!!!!!!) I mow in the rain (live in Seattle after all) and the air-intake is sucking when the engine is running. Never a problem.

@Cardinal (how the hell would rain water get in the sump!!!!!!)

Really easily if water gets into the air intake and you attempt to start the motor. The water gets sucked into the cylinder and then leaks past the rings into the sump. A common occurrence when yard machines are exposed to long term very heavy rain and they have a vertical air intake, such as those on some mowers where the air intake is on the handle to get away from dust.

Water taken in with a motor running does no harm – dissipates as steam immediately. It is often used to “de-coke” a cylinder. To do damage sufficient water has to get into the air cleaner to flood it and reach the carburetor. That usually takes a lot of rain, and usually a bit of wind. The vents are usually on the side, not the top.

It is something I have had considerable experience with, some of it very recently – in those huge storms we had a couple of weeks ago. Water damage to a mower and a wood chipper, but easily fixed.

I started it up and just finished mowing the entire yard! My next lawn care question is going to be related to whether or not I have to bag the clippings.

No biggie. Just don’t make a habit of it. I think you’re biggest concerns would be water in the gas line and your spark.

@DarkScribe seems like the go to guy on this one