Damaged piston

[chainsawMal]

Hi, this damage has happened to my mates strimmer.

 

Any ideas on the cause?

 

Its relatively new and used it for about 3 times for 30 minutes each and failed to start by the end of the 3rd time?

 

Thanks for help

[MrNick]

Possibly wrong spark plug causing damage by the electrode hitting the piston at tdc

[chainsawMal]

But its not exactly on top of were the plug is and there is no damage to the plug!

[Stumpy Grinder]

Pre-ignition

•Pre-ignition occurs when the air-fuel mixture is ignited by a hot object/area in the combustion chamber before the timed spark event occurs.

•When the spark plug firing end (tip) temperature exceeds 800°C, pre-ignition originating from the overheated insulator ceramic can occur.

•It is most often caused by the wrong (too hot) heat range spark plug, and/or over-advanced ignition timing. An improperly installed (insufficient torque) spark plug can also result in pre-ignition due to inadequate heat transfer.

•Pre-ignition will dramatically raise the cylinder temperature and pressure and can melt and hole pistons, burn valves, etc.

SG

[MrNick]

A point source of heat where the fuel ignites plus a rubbish piston. What make is it? What about warranty?

[Lazurus]

A point source of heat where the fuel ignites plus a rubbish piston. What make is it? What about warranty?

 

I have to say the piston looks like its made out of plasticine, funny looking alloy

[spudulike]

My guess would be either pre ignition or the piston had been damaged by a piston stop but the latter usually causes drop of compression and that usually stops the engine before this sort of damage occurs.

 

The engine is probably destroyed, all that aluminium has ended up in the main bearings and will knock them out unless a thorough flush out will sort them.

 

What make is it and are they OEM parts? The piston may just be of poor quality but I have never seen this sort of damage in the past - real carnage:thumbdown:

[chainsawMal]

another pic

[chainsawMal]

Its Chinese and he can take it back for replacement.

 

I have the exact same model for 4 years, mine did brilliant!

[spudulike]

You pays your money and takes your chances....looks like poor materials or the coil/flywheel had some crazy advance on it that preignition did for the piston.

 

Possibly the piston had a poor Aluminium/Silicon ratio in its construction and it didn't stand up well.

 

I could tell you how to measure ignition advance but it would put the whole of Arbtalk to sleep:lol: