How to tell if your chainsaw has seized?

What happens, why and how to fix it

/ Inspirations


Estimated reading time 3 minutes

Seizure occurs when mechanical components in contact lock up due to becoming lodged against each other, instead of moving in harmony with one another. Internal combustion engines can seize up when poor lubrication causes the piston to overheat, expand and come into contact with the cylinder.

Seizure affects both 4-stroke and 2-stroke internal combustion engines, and not just in cars, motorcycles and scooters, but in gardening tools too. What are the possible symptoms of a seized engine? What happens when a chainsaw seizes up? Your chainsaw may have seized if:

  • Carburetion is erratic at different RPMs.

  • The machine is difficult to start.

  • The pull cord locks up, preventing the machine from starting.

The first two cases are generally symptomatic of minor lockups, whereas the third indicates a more serious problem.

A frequent cause of engine seizure is overheating, which can have various causes. In 2-stroke engines, such as those found in chainsaws and other gardening power tools, seizure can be caused by:

  • Inadequate lubrication due to an incorrect quantity of oil in the mixture or insufficient or low-quality oil, such as mineral oils. On this subject, you can read our article on lubricants for garden tools.

  • Inefficient cooling: This can happen when the air intakes on the casing become clogged, or when the cylinder fins, which help to disperse heat, are covered by a layer of dirt, which acts like an insulator.

  • Incorrect carburetion: Incorrect setting of the carburettor’s mixture and air percentages can cause an increase in temperature, higher engine RPM and a lower quantity of oil, impairing the efficient lubrication of the components.

  • Non-original spare parts: This can compromise the reliability of the engine.

How to prevent seizure of 2-stroke engines?

  • Choose a quality oil for the 2-stroke engine mixture: Follow the manufacturer's recommendations in the user manual (for Oleo-Mac petrol chainsaws, we suggest EUROSINT 2 EVO or PROSINT 2 EVO engine oil).

  • Prepare mixture to the correct oil/petrol ratio: Check the user manual (by way of example, our 2-stroke engine products require 2% engine oil, i.e. 20 ml or cc per litre of petrol). On the subject of mixture, here's how to prepare it.

  • Use fresh, high-quality petrol: check the user manual for further details.

  • Clean the crankcase vents and cylinder fins regularly to ensure efficient air cooling.

  • Always consult an authorised service centre if you don't know the correct carburetion setting.

Maintenance is essential for the proper functioning of chainsaws and all other gardening power tools. Read our overview about chainsaw maintenance, or find out more on guide bars and chains in the articles what to do if your chainsaw cuts crooked and how to sharpen the chain.

We should emphasise that checking for seizure is a procedure that requires excellent technical knowledge of the product in hand, so we advise you to always have it done by an Authorised Service Centre, to avoid misdiagnosis or actions that exacerbate the problem.

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