If your lawn mower bogs down in thick grass or under any other heavy load, there are a couple of possible reasons for it. Fortunately they are also things you can fix yourself.
The quick temporary fix
The quick temporary fix almost everyone eventually stumbles upon is to tip the mower up just when you start to hear it bog down. This helps the mower discharge the clippings under the deck and save the engine, but it’s usually only temporary. If it starts happening early in the job, you can expect to have to tip the mower more and more frequently until you get it done.
Cleaning your deck to stop your mower from bogging down
The most common reason why lawn mowers bog down, especially mulching mowers, is grass clippings sticking to the underside of the deck. If your mower packs in too many clippings, there’s not enough room for the clippings to cycle and the blade to keep turning.
Fixing this is easy enough, it’s just a messy job. Pull the wire on the spark plug, then flip the mower over. Scrape away the clippings stuck to the underside. I typically use a putty knife, then come in with progressively smaller screwdrivers to scrape out anything that’s left. Then I follow up with a stiff brush.
After cleaning the deck, apply a bit of oil to it to keep the grass from sticking to it. Cooking spray is the cheapest option and works fine.
Adjust your mower height
Trying to cut too much grass can also cause it to bog down. You should only be cutting the top 1/3 of the grass. That’s best for the grass’ health and that’s what the mower is designed to cut. So as tempting as it is to lower your mower height all the way down so your cut lasts longer, doing so isn’t good for your grass or your mower, especially if it’s rained recently and the grass is wet.
You don’t have to use precision instruments to determine it. Just roll the mower onto the grass, then adjust the height of the mower until about 1/3 of the grass height is over the lower lip of the mower. That’s close enough.
Be sure to check one more thing
There’s one more thing you want to check if your lawn mower is bogging down. Check the oil. Especially early in the season, if you forgot to change or top off the oil, you’re prone to be low. Being low on oil along with these other issues isn’t a good combination, so make sure you’re got enough oil. And if you haven’t changed it this season, go ahead and change it, don’t just top it off. Topping off dirty oil won’t do your mower any favors. Instead of going to the hardware store, go to the auto parts store and buy some 10W30 synthetic. You’ll only need 20 ounces of it, but that just means you’ll get three oil changes out of two quarts.
And while you’re at it, if you don’t use Marvel Mystery Oil in your mower, I recommend you start. Here’s why.