Repair of a Honda Mower (Honda Izy) steel deck.

This webpage details the steps taken to repair the deck of a Honda Izy 46cm (18") petrol driven lawnmower.

In early 2022 I was given a Honda Izy lawnmower, with the expectation that I would either scrap it, or purchase a new steel deck at a cost of 150 (!). As expected, the engine seemed to be perfect - it started first time and ran smoothly. But it was nearly 15 years old and not worth the expense of a new deck. Many steel deck lawnmowers suffer a early death simply because people do not clean off the grass and soil after each use. This wet material acts as a poultice, promoting corrosion long after the machine has been returned to storage.

A convenient way to clean mowers after use is to wedge the handle under the exhaust pipe of a car, leaving the front wheels of the mower high off the ground (see picture below). Once the mower engine has cooled down, a hosepipe can be sued to remove all the layers of soil and grass clippings that will have accumulated. Once clean, the deck will dry in storage and corrosion should be minimal. This method is quite safe with electric mowers also - but care needs to be taken not to direct the water jet into the motor. All mowers should be run briefly after their undersides have been washed, to help dry off the surfaces. Most people don't bother to clean the undersides of mowers after use - and hence steel deck mowers last typically 10 to 15 years whereas Honda engines in particular would probably last 50 years or more, provided their oil was changed every few years.

Very few spare parts are available for petrol driven lawnmowers - and certainly not at a reasonable price - a standard ploy to encourage people to buy a new mower.

One advantage of high quality HONDA lawnmowers is that the engines are more efficient than cheaper models, and also they are considerably quieter.

This one has a dB rating of 94 - which is very considerably quieter than many machines that are rated at 97 dB.

It was manufactured in 2008 and probably neglected all its life. It as given to me in early 2022.

Metal decks used in lawnmowers are made from very thin but strong (high carbon) steel. This makes them relatively lightweight but prone to corrosion once the paint layers on the underside have been degraded.

Some pictures of Honda Izy mowers for sale on eBay show the complete front axle and deck section detached from the main body. In these cases only careful TIG welding would likely suffice as a repair.

On the mower shown, the area circled in red was (fortunately) still adequately strong - it served at least to hold the front and rear sections of the deck together!

The repair aimed to enhance the strength of the deck in this critically stressed area.

As received, there was extensive corrosion and weakness all along the front of the mover deck but (again fortunately) not extending all the way across to the edge of the deck.

This again served to keep the front section properly aligned with the main body of the deck.

Close up of the gearbox used for self-propulsion. The belt drive from the engine turns the pulley all the time, the spring loaded lever acts to engage the drive to the rear wheels.

The plug shown is for topping up the oil level - although the units are considered sealed for life.
Metal repair panels were cut out from the side casing of an old desktop computer using an angle grinder, cardboard templates having been made to the rough shapes required..

Never throw anything away - you don't know when it might come in useful.

To provide a 'key' for the resin used to bond the repair panels in place, all paint and corrosion was ground off substantial areas of the mower deck. These areas were then wiped with solvent to remove any metal dust.
View of the underside with the metal repair panels glued into place but before much of the corrosion had been removed from the body of the deck in preparation for painting.

it was judged that hammering off some of the the thick corrosion would best be done after the deck had been reinforced by the repair patches.

The repair patches glued into position using Fischer resin of the type used to bond steel fixings into masonry and concrete.

I usually have several tubes of this available - I used it to build my own garage and later my conservatory many years ago, and I am always finding new uses for it! It sets in about 5 minutes, bonds very well to metal and concrete, and is immensely strong.

Underside of the deck with rivets in place and prior to priming.

Thick corrosion has been removed by hammering and then the surface cleaned with a power wire brush and solvent.

Not all the resin filler and fibreglass patches have yet been applied.

Long rivets were used to extend through the thickness of resin (3mm in some areas) and also through the stainless steel washers shown.

I could have made a much better job of bending the repair panels into shape if I had an anvil - but that is one workshop tool I do not possess!

The curves were formed by hammering the repair panels around lengths of steel tube 50 and 75m  diameter.

Some of the rivets are shown in place.

One of the most difficult jobs was drilling the metal deck of the mower. The steel was so hard it blunted ordinary HSS drills so I had to buy some 4mm diameter cobalt drills - and those were little better. Several of them snapped and others needed sharpening every few holes. I sent them back to the eBay seller - complaining that they were of insufficiently high quality.

Showing the rivets and the 15mm diameter stainless steel washers. These had a 4mm hole size to match the rivets. A high quality metal primer was applied, followed by many layers of gloss paint - from an old can that was going to be thrown away.
Final assembly - such an arrangement can also be used to remove or replace the blade without tipping the mower onto its side. this can risk oil leaking into the air filter, which leads to extra complications.

Some types of 4-stroke petrol mowers must not be turned onto either side - only tilted backwards on their rear wheels. This again is to prevent excess oil getting into parts of the engine where it could cause damage!

Generally, 4-stroke mowers can be tipped onto the side containing the oil filler. This is a standard way of draining the oil in designs where no drain plug is provided.

How to clean just about any lawnmower - petrol engines should be allowed to cool down.

Some petrol types (including the model shown here) must only be tipped up as shown, never onto their sides. The handle can be wedged beneath a convenient exhaust pipe!

This gives safe access for judicious use of a hose pipe to remove all accumulated grass and soil from the underside.

Ideally, the blade should then be smeared with oil after being allowed to dry.

In case you are wondering - yes, the repaired Honda did start first time, despite having been given only a few dregs of old petrol.

It did misfire and stall several times during its first outing, but this was likely caused by a partially blocked fuel filter located in the base of the tank.

Repair costs:

Rivets 4
Washers 2
Metal primer 2
Cobalt drills - 0 (refunded via eBay)
Gloss paint - 0 - an old can destined for scrap.

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