How to Service a Petrol Lawnmower

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By Adam Woolcott

Why Do I Need to Service My Lawnmower?

Servicing your lawnmower is important for various reasons. It will extend the life of your machine, keep it running at its optimum performance level and reduce the risk of mechanical breakdown. We also highly recommend taking your lawnmower to a certified Webb dealer once every 12 months to keep your 3 year warranty valid. But most importantly, when you service your mower, it will keep your lawn looking its best.

Here I will show you how to carry out a lawnmower service, demonstrated with a Webb WER18HW4.

What do I need to check?

Fixing your Nuts & Bolts on your Lawnmower

Firstly, put on some gloves and then just generally check the mower. All fixings and fastenings should be secure. Lawnmowers vibrate with use so there’s potential for nuts and bolts to loosen up or fall off.

How to Fix a Broken Pull Cord

Pull cord check during a lawnmower service

Check the pull cord by gently pulling it all the way out. Make sure that there isn’t any fraying at either end. This will be where it’s attached to the handle or where it’s attached to the engine. If there is any fraying or it looks tired, you may want to replace it. It is a pain to try to start the machine and have the cord snap – so although it’s a rare issue, replacing the cord before it snaps will save time and frustration.

How Do I Replace a Spark Plug

Spark plug change during lawnmower service

As you move down towards the engine of your mower, it’s really important to remove the spark plug before further inspection. While it’s removed, you should also check the plug itself. If it’s black, covered in soot or oily – then it’s best to replace it. Especially if you’ve been finding it difficult to start your machine – an old or worn spark plug is often the cause. Also, when replacing the spark plug, make sure you only tighten to the point at which you feel resistance. Any over-tightening and it’s possible to shear off the top and ruin the spark plug.

Check Your Mowers Air Filter

Air filter check during lawnmower service

Something else that’s important to check when servicing your lawnmower is the air filter. If this has become clogged, oily, or very dusty then it can affect your mowers performance. Once removed, if it looks generally clean, give it a gentle tap. This should help to remove any dust or build up. However, if it’s soiled and oil stained then it might be best to replace it with a new one.

How and When to Replace Lawnmower Oil

Changing oil during a lawnmower service

Probably the most critical thing to check is the oil. Too little, too much or very old oil can severely damage your machine. If the oil is black, very thick or very low then it’s essential to replace it with brand new oil. Make sure that it is lawnmower oil and the correct grade for your mower. This information should be in the manual.

When replacing the oil, run the machine for a few minutes. This will heat up the oil in the machine and make it easier to drain. Remove the oil cap (this will usually have a dipstick attached) and then tilt the mower on its side. Be sure to do this over a receptacle for collecting the spent oil as it pours out. Once the old oil has been full removed, bring the machine back to the upright position. Wipe away any oil on the machine and take the oil to a registered point for disposal. When adding fresh oil, it’s very important to add the specified amount in the manual. You may find it easier to use a funnel and add the oil gradually. Once added, replace the oil filler cap.

Clean Your lawnmower Collection Bag

Now that the engine part of the servicing has been completed, it’s time to check the collection bag/box, the underside of the deck, and the blade. Wet or fresh grass in the spring can be sticky and build in certain areas. When it dries up it can be very difficult to remove. Wash out the inside of your collection bag regularly and allow it to completely dry before using again. This will maintain optimum airflow and make sure that the grass clippings are properly collected – with the grass bag filling to the top.

To remove old grass from under the mower, tilt the mower backwards. Do this by pushing the top part of the handles towards the ground, never to the side. Make sure the spart plug has been removed and then scrape away all of the old dried grass. Finally, check the blade. If the blade is slightly chipped or blunted then you can sharpen it yourself with a file. However, a really damaged blade should be professionally sharpened or replaced.

There are simple procedures that will keep your mower in tip-top condition and ensure many hours of hassle-free mowing – so you can really enjoy your garden this year.

Happy gardening,

Adam Woolcott

Adam Woolcott has over 30 years of experience as a professional gardener and has many accolades, but is probably best known for his four Gold Medals at The Royal Horticultural Society’s Chelsea Flower Show and his three BBC/RHS People’s Choice Awards at the show (of which he is particularly proud) which he won as one half of Woolcott & Smith.

2 thoughts on “How to Service a Petrol Lawnmower

  1. Peter Trevor Rice says:

    Has my Webb Mower got a fuel overflow pipe as there is petrol coming from a small hole which is part of the carburettor, I only notice the petrol coming out when I have just filled up with Petrol, it does not seem to leak when 50% full.
    I would be very grateful for your help in this matter.

    • Nathan Dukes says:

      Good morning. Two of the many causes of this problem could be old or contaminated fuel being put into the machine. We do not recommend using any fuel that is more than 28 days old (purchased from a petrol station, more than 28 days ago) or fuel that is in any way contaminated. Both of these can cause a blockage in the carburettor, that essentially floods and causes the problem you are experiencing. You may find that emptying the fuel and filing with fresh fuel resolves this issue. Alternatively, having the machine inspected by a service and repair agent to see if the carburettor needs cleaning. Kind Regards. Webb Garden Power

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