Non-motoring > Smoking lawnmower Miscellaneous
Thread Author: TheManWithNoName Replies: 7
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New Mon 13 Jun 11 13:59 
 Smoking lawnmower - TheManWithNoName
I have a 4 stroke unleaded lawn mower which I fired up on Saturday and cut the grass with.
I'd almost finished when it started running roughly and at slower revs than normal and there was a hint of blue smoke from the exhaust. usually I don't observe any smoke except on start up.

There appeared to be oil in it but I topped up just in case and left it cool.
It was still running roughly when I fired it up again the next morning.

Any ideas what might be causing it?
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New Mon 13 Jun 11 14:08 
 Smoking lawnmower - R.P.
Take out the plug - check it for fouling, give a goof clean, my bet if that doesn't work is that it's either burning oil or contaminated fuel.
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New Mon 13 Jun 11 14:18 
 Smoking lawnmower - Armel Coussine
I would add that the other thing to check is the carburettor and its air filter. Clean air filter, check float level, make sure jets are clear.

If ignition and carburation are more or less correct, it might be something worse. But it probably won't come to that.
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New Mon 13 Jun 11 14:30 
 Smoking lawnmower - madf
Check the cooling airways are not blocked with grass. I ruined a lawnmower like that: the piston partially seized and is was never the same after.

Or blcoked air filter/fuel system/dirt/
Last edited by: madf on Mon 13 Jun 11 at 14:30
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New Mon 13 Jun 11 15:22 
 Smoking lawnmower - Bigtee
Has it been on it's side?

Had one here and found oil in head after falling over, a clean and a mop up new oil sorted.
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New Mon 13 Jun 11 19:55 
 Smoking lawnmower - WillDeBeest
On its side is enough. Mine hadn't even gone right over but our old lawn had some awkward, steep banks and I reckon that's how it happened. It was due for a service anyway but the workshop found nothing wrong and it's had no trouble since.
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New Mon 13 Jun 11 21:14 
 Smoking lawnmower - Harleyman
If it's a Briggs and Stratton engine, or copy thereof, don't sweat. They're side-valves, and therefore designed to burn oil; a good reason to check the level regularly. Plus as said above being on a bank would exacerbate the smoking.

Mucky fuel is often a problem since we tend to fill mowers from cans.
Last edited by: Harleyman on Mon 13 Jun 11 at 21:15
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New Tue 14 Jun 11 08:28 
 Smoking lawnmower - Cliff Pope
There's a right and wrong way to tip mowers when you need to clear compacted wet grass from underneath.
Tip it the wrong way and oil flows into the exhaust manifold and back into the combustion chamber. Then when you start up, you get clouds of blue smoke and it takes quite a while of rough running to clear.

Tip it the other way of course and petrol dribbles out from the carburettor and leaves a dead patch of grass.
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