Engine troubleshooting

Iveson

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I have an old (1965) McLane edger with a B&S either 2 or 2 1/2 HP motor. It means a lot to me after all these years. My problem is that it starts easily and runs well for about 8 to 10 minutes, then begins to smoke a run roughly, then dies.

I have replaced the sparkplug.
Cleaned the carburetor.
Cleaned the gas tank, good clean gasoline in it.
The gaskets are good.

After all of this, again it starts normally. Runs solidly, good throttle response. After 8 to 10 minutes it starts sputtering, throwing out a little blue smoke, then kills. I have no idea what else to try. Does anyone have a suggestion? I would most appreciate it.

Iveson
 

Boobala

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I have an old (1965) McLane edger with a B&S either 2 or 2 1/2 HP motor. It means a lot to me after all these years. My problem is that it starts easily and runs well for about 8 to 10 minutes, then begins to smoke a run roughly, then dies.

I have replaced the sparkplug.
Cleaned the carburetor.
Cleaned the gas tank, good clean gasoline in it.
The gaskets are good.

After all of this, again it starts normally. Runs solidly, good throttle response. After 8 to 10 minutes it starts sputtering, throwing out a little blue smoke, then kills. I have no idea what else to try. Does anyone have a suggestion? I would most appreciate it.

Iveson

You did.nt mention the OIL level. and if it's clean or not, did you remove the engine "shroud" and clean the cooling fins ..?? is the plug covered with black carbon ?? what color smoke is it emitting , black or blueish white,what gaskets are you referring to ..??
 

Iveson

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The oil level is fine. Changed not long ago. The smoke when it gets hot is blueish/white. Have not attended to the cooling fins, and do not know how to do that. The gaskets I mentioned were the gasket sealing the carb to the engine housing and the gasket connecting the fuel tank to the mount. The engine shroud is off. Tell me more about these cooling fins please.
 

Iveson

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Forgot. The spark plug following the engine dying is indeed wet and a bit blackened.
 

bertsmobile1

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Spend $ 20 on a red neon tube in line spark tester and fit it to your mower then go mow.
If the tube flashes iregularly when the engine starts playing up and does not flash when you are cranking after it has stopped but still hot then the ignition module is toast & needs replacing.
If you get good strong flashes then it is a different problem.
Give it a go then get back to us
 

cpurvis

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The oil level is fine. Changed not long ago. The smoke when it gets hot is blueish/white. Have not attended to the cooling fins, and do not know how to do that. The gaskets I mentioned were the gasket sealing the carb to the engine housing and the gasket connecting the fuel tank to the mount. The engine shroud is off. Tell me more about these cooling fins please.

Cooling fins are thin projections, cast integral to the cylinder barrel and cylinder head. Their purpose is to increase surface area of the exterior of the cylinder and head so that heat will radiate from them. Air is drawn in through the screen under the recoil starter by the fins atop the flywheel and is pushed into the sheet metal shroud which is shaped to direct the airflow over the cooling fins. This is how air cooled engines work. Some air cooled engines don't need the fan and shroud, such as motorcycles and airplanes.

Obviously, anything such as dirt, clippings, grease accumulating on these fins acts as an insulator and reduces their efficiency. Cooling fins need to be clean.

FWIW, ALL engines are air cooled. "Liquid cooled" engines just have a middleman (the radiator) which transfers the heat to the air.
 

cpurvis

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Cooling fins are thin projections, cast integral to the cylinder barrel and cylinder head. Their purpose is to increase surface area of the exterior of the cylinder and head so that heat will radiate from them. Air is drawn in through the screen under the recoil starter by the fins atop the flywheel and is pushed into the sheet metal shroud which is shaped to direct the airflow over the cooling fins. This is how air cooled engines work. Some air cooled engines don't need the fan and shroud, such as motorcycles and airplanes.

Obviously, anything such as dirt, clippings, grease accumulating on these fins acts as an insulator and reduces their efficiency. Cooling fins need to be clean.

FWIW, ALL engines are air cooled. "Liquid cooled" engines just have a middleman (the radiator) which transfers the heat to the air.

I left out probably the most important detrimental effect of dirt, clippings and grease accumulating on the the cooling fins--it blocks airflow over them.
 
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