Small engines can be difficult to diagnose when it comes to temperature, as many do not come with any sort of temperature monitoring gauge. This is unfortunate, as not paying attention to the temperature of the engine can cause catastrophic damage. An overheating engine can cause components to seize up or, in extreme cases, engine combustion.
The primary cause behind engine overheating is a dirty engine. Dirt and debris can get into the vents and block the air intake, meaning that cool air cannot flow over the engine and cool it. Take off the mower casing and clean out all of the debris inside. Use blasts of compressed air, a vacuum, or a toothbrush to knock debris loose.
If this doesn’t fix the overheating problem, the next most common cause of the problem is a low oil level. A low oil level means that lubricant is not circulating through the engine enough, meaning that friction is not being reduced – one effect of friction is heat. Allow the engine to cool down, then add enough oil to bring the level up to a sufficient point.
Next on the list is damaged or missing cooling fins or a damaged shroud. The cooling fins and shroud help to dissipate heat, moving it away from the engine and into the airstream. Broken or missing fins don’t direct the heat away, increasing the potential for overheating. Fix or replace the fins or shroud to solve your overheating problem.
If these simple fixes don’t solve your overheating issues, it may be something slightly more complex. The next thing to check is your fuel-air mixture. A lean mix means there is more air than usual in the combustion chamber. More air translates to detonation of fuel instead of combustion, which causes more eat to be created. To fix this, you will need to consult your owners’ manual and adjust the carburetor for a mix that is heavier on fuel.
The final most likely cause of overheating in your push mower or riding mower engine is a leaky gasket in the carburetor. A leaky gasket will have the same effect as a lean fuel-air mix, but unintentionally so. A leaky gasket creates a gap that allows fuel in and air out, leading to a lean mix. To fix this, your carburetor will need to be overhauled, which you can do yourself – see your manual for directions – or, more likely, send off for repairs.
So don’t allow your engine to overheat for too long – what could be a simple fix that only takes moments of your time could lead to equipment failure that could call for expensive repairs or even the need to replace your mower.