Lawn mower smoking when hot

[dean]

Hello all,

I have a 10 year old Crafstman (Briggs and Stratton) 1 cylinder rider mower, and its done me well, but now if it struggles at all on long grass, it gets hot and starts smoking. It smokes a little all the time anyway.

I've cleaned the air filter, is there anything else that I could check before trashing it?

Thanks!

DeanB.

[dpb]

If it's burning oil and losing compression, it's basically toast. Using a heavy oil may help a little for a short while, but once they're that bad, there's little to be done.

Depending on the initial quality of the mower itself and what shape it's in, could put a replacement engine on it, but cost of repair of a relatively small horsepower engine is usually so near the cost of a new one I'd not recommend that route.

[Stormin Mormon]

Two t hings come to mind:

1) Remove the motor cover and clean the fins around the spark plug. Actually, clean the entire outside of the motor. May not be cooling properly. 2) Change the oil, and put in Castrol 10 W 30. Castrol is the only brand that quieted the rod knock in my last truck for more than a couple days after an oil change.

If the motor continues to smoke, change the oil again. But this time use two stroke gas mix oil in the crankcase (do not mix it with the gasoline) and check the oil before you start the mower. Every day you run the mower, check the oil first.

[Srgnt Billko]

I was about to say the same thing about cleaning the fins and block.

But I would recommend either straight 30 weight oil or maybe even 40 weight rather than the variable viscosity stuff.

[Steve Barker]

Take all the sheet metal off the engine and clean out the cooling fins. This may help a bit, but it sounds like it's pretty well worn out.

[dean]

The engine has a round wire gauze mesh over the top, which spins round with the engine. This I regularly swish around with my hands to clear off the dust and crap that gets on there. Is there more to clearing the 'fins' than this? Under the mesuh are fan-shaped spiral fins that pull air down over the engine, and they look clean.

[tksirius]

There are fins around where the sparkplug sits. Those fins actually provide the cooling of the motor (with the assistance of the flywheel blowing air across those fins(the item you are washing off))

I would use the mower till it dies. Changing the oil to a straight

30 weight is your best bet. The 10w30 types of oil are designed for winter type temperatures, not for warmer days.

Use the 10w30 in your snowblower, not your mower. If you find the motor burning oil, going to a heavier weight is an option. Others may like the Marvel Myster Oil. (mix a little with your oil in there and give it a go.)

Tom

[dean]

I've been using Mobil 1 oil.

Thanks, I'll take another look at the engine.

Cheers to all,

Dean

[barry]

The fins you're talking about are on the flywheel, purely to move cooling air down past the fins on the head and block. Over years of use, some debris generally gets past whatever strainer is at the air entry, typically lodging between the housing and the top of the block/head fins. Which kinda makes cooling difficult.

What others have suggested is to pull the sheet-metal housing off the engine and blow/scrape/wire-brush the debris off. I'll bet you have lots of cooked-on crud there, as indicated by the smoke.

HTH, J

[dpb]

...

I'm assuming (and betting) the smoke is from the exhaust not from charring of external trash and the cleaning will be of marginal if any benefit to his symptoms (although it can't hurt and is a good idea to remove stuff in general).

[mm]

It's hard to tell how long you mean by long grass or how much more it gets hot or smokes then.

But the cooling fins around the spark plug have more to so with it getting hot than do the spiral ones on the top. When it's cold you can clean much of the junk out of those fins with flat screwdriver, if it is too hard to take off the sheet metal cover above (which only has about 4 bolts, one near the spark plug and one at each front cover), you may be able to clean much of that with the same screwdriver.

P&M

[businessman]

Bore out the cylinder, use an oversize piston and new rings. Good as new!