Are you noticing your lawn mower leaves a trail of grass clippings in its path? This likely points to a problem in your lawn mower’s suction system. Most of the time, suction problems can be fixed with just a couple of tools and a few replacement parts. So let’s dig in to see what is likely causing your lawn mower to have reduced suction and what you can do to improve it.
Improving Lawn Mower Suction (The Short Answer)
Suction systems rely on the cooperation of several mower parts to complete the suction process. Parts such as blade sails can break down and fail to lift the grass, grass chutes can become blocked, and bag airflow can become limited. If one of these parts has a problem, it will reduce the efficiency of the entire suction system.
The Problems that Poor Mower Suction Can Create
If your lawn mower has poor suction, then you’re going to notice problems with your yard and mower. I’m guessing that you are already experiencing one or two of these already. Here are a couple of problems you could encounter.
- Lawn Not Being Cut Correctly
- Grass Not Being Collected
- Mower Bogging Down
- Engine Stalling
- Mower Engine Overheating
- Poor Fuel Efficiency
What Equipment You’ll Need on Hand
Now that you know some of the symptoms of poor lawn mower suction, let’s look to see how you can make improvements. Here is a list of tools and parts you’ll need to have on hand to complete the fixes successfully.
Tools Required to Improve Lawn Mower Suction
- Scraper
- Flat Head Screw Driver
- Socket Wrench
- Blade Brace
- Water Hose
Parts Required to Improve Lawn Mower Suction
- New Blade
How to Improve Lawn mower Suction (Step By Step)
Now that you have everything you need, let’s look at what could be causing your lawn mower to have reduced suction and how to remedy these issues.
Wet Grass
Avoiding wet grass isn’t really a fix; it’s simply making sure you’re cutting your lawn in the best conditions. Wet grass is much harder for the blades to cut. It also creates the added problem of clippings clumping together, making suction difficult. Heavy, wet grass will give even the best mowers a problem with suction. So before you grab your tools, double-check the lawn is nice and dry.
Worn or Damaged Mower Blades
Blades have two main edges, the cut edge, and the sail edge. The sail edge is the back of the blade that lifts the grass up into the deck once the grass is cut and loose, plus generates airflow in the deck.
Unfortunately, the sail edge can become damaged and worn over time, reducing suction efficiency. To check this, tilt over your lawn mower and inspect the sail edge of the blade. If you find it damaged or worn, you’ll want to replace the blade. Let’s go over how to replace the mower blade.
Remove the Spark Plug
Like any repair under the deck, you’ll need to remove the ignition cable connected to the spark plug and tuck it out of the way.
Tilt Over the Lawn Mower
Next, tilt over the lawn mower. Make sure you tilt it over in the correct direction so that oil doesn’t flow into the air filter.
Brace the Blade
Position your blade brace so the blade cannot move in the direction you’ll remove the bolt.
Remove the Center Bolt
Next, use your socket wrench to remove the center bolt attaching the blade to the spindle or crankshaft.
Install the New Blade
Place your new blade in the correct orientation on the mower. You’ll want to make sure that the blade sail faces into the mower’s deck.
Replace the Center Bolt
Reinstall the bolt and any washers and spacers onto the mower.
Remove the Brace
With the new blade installed, you can remove the brace and check that the blade is installed correctly and moves freely.
Upright The Lawn Mower
Finally, upright the lawn mower and test how the new blade performs.
Clogged Mower Deck & Clogged Grass Chute
Because grass contains water, grass clippings will naturally clog the mower deck even when you mow in dry conditions. Grass clippings will start to collect under the lawn mower in the path to the collection bag.
Again, tilt over the lawn mower and inspect the path the grass takes to the bag. If you find that there is a buildup of grass clippings, you’ll need to use your tools to clean out the mower. Here’s what you’ll need to do.
Remove the Spark Plug & Tilt Over the Mower
Like the previous fix, remove the ignition cable and tuck it out of the way. Then tilt over the lawn mower the correct way to avoid oil getting into the filter.
Scrape Out Grass Build-up
Take your scraper and scrape off any grass build-up. Make sure you work the whole area and get right into the corners. For tighter spaces, I like to use a screwdriver.
Plugged Collection Bag Screen
The final part in the grass’s path is the bag itself. Lawn mower collection bags are made of a material that allows air to flow through them. Over time grass blocks the material and stops the airflow. This has the same effect on suction as having a full collection bag.
A good way to tell if the collection bag is clogged is if you see the bag blowing up like a balloon because the air can’t escape. An additional test is to remove the bag and test the rest of the lawn mower. If the mower throws grass out of the discharge chute well, it is most likely the bag causing the suction problem.
Here’s my approach to cleaning out the collection bag.
Shake Out the Collection Bag
Remove the collection bag and give it a good smack with your hand. Repeat this to free up the loose debris collected in the mesh material.
Wash the Bag
Next, use your hose to wash the bag. I like to use a jet on the end of the hose to get a powerful spray to break down the dirt. Also, it’s best to wash the bag from the outside. This blasts the dirt into the inside and helps get most of the dirt out.
Dry the Bag
Before you use the bag, allow it to dry out completely. If you’re in a hurry, then you can put it back on the mower and allow the air created by the suction system to dry it out. I suggest doing this on a hard surface like the driveway so that the mower doesn’t accidentally put clippings in the bag.
Bagger Not Secured or Attached Properly
Air flowing through the mower’s discharge path is going to look for the path with the least resistance. If your bag isn’t mounted correctly and there is a gap between the mower and the bag, grass will look to escape.
Start by trying to reattach the collection bag. If you find that you are having difficulty, then inspect the mounting points. It’s common for grass to build up and obstruct the brackets.
Lift the Chute Guard
Start by lifting the clipping guard. This is the guard that stops the clippings from shooting straight out when a bag is not in place.
Clean Out the Mounts
Use your scraper and flathead screwdriver to give the area a good cleaning. You should do this the same way you tackled cleaning the mower’s cutting deck.
Damaged Lawn Mower Deck
You may notice that when you are cutting the lawn, the grass is exiting the mower in places it shouldn’t. The lawn mower’s suction is affected anytime that air escapes or is blocked.
If this is the case, your mower’s deck is likely damaged. This is especially common in older mowers as they tend to develop holes in the lawn mower deck.
Start by cleaning out the deck and inspecting it. If you find that your mower’s deck has damage from rust, you could consider carrying out a rusted mower deck repair. This can be done in a number of different ways, including such processes as fibreglassing.
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