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J.R., Small Engine Technician
Category: Small Engine
Satisfied Customers: 7445
Experience:  Owner of outdoor power equipment business, repairing all makes and models.
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21hp model331877-0805-e1 25 hrs on motor, riding mower yearly

Resolved Question:

21hp model331877-0805-e1 briggs (2007) 25 hrs on motor, riding mower yearly regular maint air oil etc sears wont cover warranty 3 wks past date. it started pumping blue smoke and using oil under a load no smoke at any rpm when not under load good power easy start no misfire or other symptoms? air cleaner, muffler all clear no obstruction what is the valve clearence supposed to be? I do see small evidence of smoke in the crankcase when i remove the dip stick to check oil
Submitted: 7 years ago.
Category: Small Engine
Expert:  J.R. replied 7 years ago.
The valve clearance should be .003" on the intake and .005" on the exhaust.

To adjust the valves perform the following. Remove the valve cover. Rotate the engine CLOCKWISE until the piston is at top dead center on the compression stroke (both rocker arms will be loose). You will then need to use something to measure with and then turn the engine until the the piston travels down 1/4" in the cylinder bore. Use a pencil and stick in the plug hole and find a reference point and put a mark on the pencil. Pull the pencil out and then put another mark on it 1/4" higher. Put the pencil back in the plug hole until it touches the piston and then turn the engine CLOCKWISE until the top XXXXX XXXXXnes up with your reference point. Once you have the piston set at this position you will need to check your clearances. You will then want to adjust the clearance accordingly with the adjustment screw.
Customer: replied 7 years ago.
my major concern was the oil consumption and blue smoke is there any other possible cause other than a broken oil ring it also exhibits suction at the fill cap when removing and replacing the dip stick with the engine running and oil spatters out the dip stick hole did not know how this pressurized oil system works this is not correct i assume i could not find any crankcase breather system i found valve clearence on line and they were within specs
Expert:  J.R. replied 7 years ago.

See attached link. The breather is item 584 in the picture(upper right). It is under the flywheel.

Customer: replied 7 years ago.

thankyou for the breather location but??? could this be the source of the oil consumption problem? before i start tearing it apart this is a very new motor with limited dust condition in its short operational life span also i am a reasonably skilled mechanic

can i replace the oil rings with the engine in chassis my question still goes to the oil consumption (very sudden) and blue smoke

Expert:  J.R. replied 7 years ago.

The breather could be plugged or a ring could have broken. The engine will have to be pulled to change the rings.

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