4 Stroke Lawnmower

[stanbesida]

My lawnmower wouldn't start so I stripped the carburettor down and cleaned the float chamber etc. I re-built it but it still wouldn't start so I removed the spark plug and pulled the recoil cord to clear it and I heated the spark plug up. There was black oil coming out of the hole, and there was oil inside the spark plug, can anybody tell me what has caused this, and how to resolve it please?

[tonyav]

Possibly the piston rings have failed.

[tonyav]

https://www.youtube.com/watch?v=nYjnMm8EkEo

[stanbesida]

many thanks for your help

[jollyroger66]

Had the same problem. Because the sump plug would not budge,To change the oil I tipped the mower upside down. The cylinder then built up with oil. After refilling with oil, the engine would not start and the plug was covered in oil. I used a plumber's torch to burn up the oil through the spark plug hole. Tickled the carb to get fuel through. When it did fire and start up, clouds of black smoke for a couple of minutes and then all back to normal. Hope you understand this, but it is Saturday night.

[tonyav]

By the way what make of engine is it ?.

[stanbesida]

Hi jollyroger66, I think that you have hit the nail on the head as I had to remove the engine to enable me to get to the float chamber, and the oil went everywhere. You say you burnt the oil out using a plumbers torch, how long did that take, and how did you know when it was fully cleared out? I was toying with the idea of squirting some petrol through the spark plug hole to try and clear the oil out of the chamber, but I wasn't sure if that would work.

[jollyroger66]

Hi Only for a couple or so bursts of 2 seconds. Each time black smoke would blow out the spark plug hole. Good look.

[retrocop]

Well done jollyroger. Glad it worked for you. I would never apply direct heat from a blow torch to an engine cylinder head in case of distortion between head and barrel. If I tried that it would of ended in a disaster. :-(

[jollyroger66]

Yes you're right retro. stanbesida, Sorry, you should get professional advice.

[tonyav]

. I would never apply direct heat from a blow torch to an engine cylinder head in case of distortion between head and barrel. If I tried that it would of ended in a disaster. :-(

Especially if it's an alloy head and a cast iron block.

[retrocop]

jollyroger
Not criticising your technique. It worked for you. Just pointing out some pitfalls to those who try it. I am sure I would not have the same luck or success. :-)

[jollyroger66]

Hi, Was curious if you managed to get it running.