How to Rebuild a Lawnmower Engine in 6 Steps

What You'll Need
Socket Set
Piston Rings
Cylinder rings
Oil Seals

Rebuilding a lawnmower engine can help to improve the efficiency and speed of your engine. Rebuilding a lawnmower engine without the manual for the engine can be challenging to say the least, however with a bit of common sense you shouldn't have any trouble.

If you follow the basic steps below then you should be able to rebuild any lawnmower engine. You may also have to do other individual steps in some circumstances depending on the model and type of lawnmower you have.

Step 1 - Disassembly

The first thing that needs to be done is disassembling the engine. This is actually quite easy and the only complicated bit will be trying to remember where everything goes. Remember to drain oil from the engine before disassembling it and put the used oil into a safe container so you can take it to an authorized disposal site later.

When you've finished draining oil, take the engine apart. As you remove each part, you should wash it with soapy water. Check the condition of the pieces as you remove them to ensure that there is some life left in them. If the parts are too badly damaged or worn then they will need replacing.

Step 2 - Extra Components

Once you have decided what you can and can't use you can then go about purchasing the extra components required to rebuild the engine. Make sure that you buy the very best quality components available.

Step 3 - Sealing Cylinders

Check the size of cylinders used on your engine. If any of the cylinders are larger than standard, then standard cylinder rings won't be any good. You could bore the cylinder so that it is slightly bigger than standard so that an oversized cylinder ring can be fitted.

Step 4 - Replacing the Gasket

The gasket needs to be replaced now, if you're using a new gasket then check that this seals the entire engine. If the gasket leaks or exposes the engine then this will make damage much more likely during normal operating conditions. This will mean that you may have to rebuild your engine more often.

Step 5 - Replacing Air Filters

Now the air and oil filters will need replacing. After this the spark plugs can be replaced. When you are fitting new spark plugs you need to ensure that they are tightly done up. If one of the plugs is loose then this can stop the engine from firing and working properly. It's important that the spark plugs are tight to ensure the engine works as it should.

Step 6 - Testing

Now all you need to do is check that the engine still works. Try to turn the engine over and then run it on full throttle for a couple of minutes. Allow the engine to cool down and check the oil. It's useful to change the oil after running the engine the first time because it will help to remove any bits of metal which were dislodged when doing the work; if these are left in the engine then they could cause lots of damage.