Best way is to use some kind of heat while doing this. Cold soaking with PB Blaster or MMO is kind of a waste of time. If you can get the piston out and do a proper cleaning....... Rings are not that much if still available. That way you will get a 100% visible on her.
Craftsman 917.28712 runs fine but white smoke
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jlatenight
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Thanks for the replies. If it turns out I do need new rings, do I have to hone the cylinder, or could I try just replacing the rings and see what happens?
mechanic mark
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Absolutely yes use a cylinder hone on the end of a drill.
If you have the time watch Derrick Bieri on youtube "Vise Grip Garage", or Motor Trend "Roadworthy Rescues".
If you have the time watch Derrick Bieri on youtube "Vise Grip Garage", or Motor Trend "Roadworthy Rescues".
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shadetree#1
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White smoke?
and 120 compression does not indicate bad rings.
What is the chance that the engine oil is contaminated with gasoline?
I would do a leak down test and remove the OHV valve cover and listen for air into the push rod galley if it's blue smoke and eating oil. Air going into the push rod galley indicates a blown or leaking head gasket which is common on the single cylinder inteks 31 and 33 series engines.
White smoke usually indicates burning water.
Air cooled engines do not burn water unless ??????????
and 120 compression does not indicate bad rings.
What is the chance that the engine oil is contaminated with gasoline?
I would do a leak down test and remove the OHV valve cover and listen for air into the push rod galley if it's blue smoke and eating oil. Air going into the push rod galley indicates a blown or leaking head gasket which is common on the single cylinder inteks 31 and 33 series engines.
White smoke usually indicates burning water.
Air cooled engines do not burn water unless ??????????
jlatenight
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So I did exactly this and same thing. I replaced the carb (cheap) and same thing. I'm thinking I should crack her open now. Not sure what else to try. When I do, I'll check the rings. if they're stuck, should I just clean and free them, or put new ones on. If new ones, do I need to hone the cylinder? I hope not. I don't have access. If I need to take this to the shop it's going to cost me big $$.
It runs fine, it sounds fine, plenty of power, no oil in the air filter. Just smokes like Chong.
shadetree#1
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If you have not cracked her open yet.
take a oil squirt can and inject some motor oil into the spark plug hole spin the engine over by hand couple turns then do the leak down test again and if it's the rings your 60% leakage will get to less leakage and the compression should go up also if it's the rings.
The motor oil only temporary seals the rings blowby. Another test is to use a vacuum/pressure gauge (compound gauge 0-10 pressure, 0-30 vac, automotive type for about $15) and measure the crankcase vac/pressure. (you can review this test on-line) On a good engine the crankcase will have a slight vacuum, bad rings will produce a pressure. Just another thought you might pull off the breather hose from the carb throat and start the engine and see if you see any smoke or oil coming out of the breather tube. A leaking breather check valve should also not be overlooked. You can review it's operation and how to test on-line.
The 60% leak down test you made is a hint of internal leakage and you are now trying to determine if it's the rings and worn cylinder. You need to have the cylinder mic'ed to see if it's within specs if you are going to re-build/re-ring for yourself. New rings will not do any good for very long if the cylinder is out of spec's.
Sometimes what causes the rings to go away fast is someone when doing carb work accidently left off the breather hose at the throat of the carb and this bypasses the air filter and the engine will suck lots of dirt into the carb throat. This breather hose is in behind the carb throat intake on yours and most Briggs and Kohler small engines and is easily overlooked and not readily apparent that it's off until the engine has already sucked lots of debris into the carb throat bypassing the air filter.
Those engines are also know for head gsket leaking between the oil galley and the cylinder, but you said you replaced the head gasket.
take a oil squirt can and inject some motor oil into the spark plug hole spin the engine over by hand couple turns then do the leak down test again and if it's the rings your 60% leakage will get to less leakage and the compression should go up also if it's the rings.
The motor oil only temporary seals the rings blowby. Another test is to use a vacuum/pressure gauge (compound gauge 0-10 pressure, 0-30 vac, automotive type for about $15) and measure the crankcase vac/pressure. (you can review this test on-line) On a good engine the crankcase will have a slight vacuum, bad rings will produce a pressure. Just another thought you might pull off the breather hose from the carb throat and start the engine and see if you see any smoke or oil coming out of the breather tube. A leaking breather check valve should also not be overlooked. You can review it's operation and how to test on-line.
The 60% leak down test you made is a hint of internal leakage and you are now trying to determine if it's the rings and worn cylinder. You need to have the cylinder mic'ed to see if it's within specs if you are going to re-build/re-ring for yourself. New rings will not do any good for very long if the cylinder is out of spec's.
Sometimes what causes the rings to go away fast is someone when doing carb work accidently left off the breather hose at the throat of the carb and this bypasses the air filter and the engine will suck lots of dirt into the carb throat. This breather hose is in behind the carb throat intake on yours and most Briggs and Kohler small engines and is easily overlooked and not readily apparent that it's off until the engine has already sucked lots of debris into the carb throat bypassing the air filter.
Those engines are also know for head gsket leaking between the oil galley and the cylinder, but you said you replaced the head gasket.
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shadetree#1
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Add to my previous post:
Also something I've encountered when doing a leak down test on a small engine that is a oil burner.
The rings and cylinder is already loaded up with oil already and a leak down test will sometimes indicate that the leakage past the rings is not as severe as it really is due to excess oil already in the cylinder and on the rings.
When I see a small engine that is showing the leak down as on the edge cold, I run the engine to get the oil warmed up and the leak down will sometimes quite a bit lower.
Keep in mind on that engine you need to do the leak down test with the piston 1/4 past TDC. (or remove both push rods to make sure that both valves are closed when at TDC. (at TDC the intake valve can be partly open on that engine)
Also something I've encountered when doing a leak down test on a small engine that is a oil burner.
The rings and cylinder is already loaded up with oil already and a leak down test will sometimes indicate that the leakage past the rings is not as severe as it really is due to excess oil already in the cylinder and on the rings.
When I see a small engine that is showing the leak down as on the edge cold, I run the engine to get the oil warmed up and the leak down will sometimes quite a bit lower.
Keep in mind on that engine you need to do the leak down test with the piston 1/4 past TDC. (or remove both push rods to make sure that both valves are closed when at TDC. (at TDC the intake valve can be partly open on that engine)
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Well I see one problem and that is the 120 psi on single cylinder Briggs with an ACR. It indicates a bad camshaft ACR. Also these 310000 engines are bad about blowing hte head gasket between the cylinder and the push rod galley. When this happen oil is blown thru the breather tube and the carburetor inhales it and the engine burns the oil.
Removing the rocker valve during the leakdown test will show more air escaping from the push rod galley then the dip stick tube.
Also these engine can pass a standard leakdown test and still have a worn out cylinder. It takes a modified leakdown test to fully check the piston stroke in the cylinder. This requires disabling the valve train which is easily done on an OHV engine.
Removing the rocker valve during the leakdown test will show more air escaping from the push rod galley then the dip stick tube.
Also these engine can pass a standard leakdown test and still have a worn out cylinder. It takes a modified leakdown test to fully check the piston stroke in the cylinder. This requires disabling the valve train which is easily done on an OHV engine.
shadetree#1
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StarTech:
Right about the camshaft ACR failures on the 31 and 33 series and also the head gasket leaking into the push rod galley.
I see he has replaced the head gasket maybe twice and no immediate results when he first started the engine.
He has not complained about the engine hanging up on the compression stroke when cranking indicating that his ACR on the cam is bad YET.
He calls that smoke white. I would bet that it's actually the BLUE oil smoke since it's gulping oil.
I've also seen them Briggs engines pass a leak down test if the test is not done correctly, especially a oil burner.
I do not put a lot of money and time into the single cylinder Briggs Inteks 31 and 33 series due to the high failure rates of the engine internals and the usually wimpy carbs. It is also a waste of time and money throwing China parts into them especially the camshaft and the $100 Briggs OEM camshaft has high failure rates and can fail anytime. When it fails small pieces will usually destroy the rest of the engine if the engine is running at a high rpm when the ACR flies apart internally.
I usually just find a good used old model Briggs twin L-head, Single cylinder L-head or even a twin Intek as a replacement for the 31 and 33 series if the tractor and deck is ok and worth the effort the restore, if not it goes to my salvage for parts.
Really a shame how sorry the Briggs OHV 31 and 33 series engines are made.
Briggs should be ashamed of themselves.
Right about the camshaft ACR failures on the 31 and 33 series and also the head gasket leaking into the push rod galley.
I see he has replaced the head gasket maybe twice and no immediate results when he first started the engine.
He has not complained about the engine hanging up on the compression stroke when cranking indicating that his ACR on the cam is bad YET.
He calls that smoke white. I would bet that it's actually the BLUE oil smoke since it's gulping oil.
I've also seen them Briggs engines pass a leak down test if the test is not done correctly, especially a oil burner.
I do not put a lot of money and time into the single cylinder Briggs Inteks 31 and 33 series due to the high failure rates of the engine internals and the usually wimpy carbs. It is also a waste of time and money throwing China parts into them especially the camshaft and the $100 Briggs OEM camshaft has high failure rates and can fail anytime. When it fails small pieces will usually destroy the rest of the engine if the engine is running at a high rpm when the ACR flies apart internally.
I usually just find a good used old model Briggs twin L-head, Single cylinder L-head or even a twin Intek as a replacement for the 31 and 33 series if the tractor and deck is ok and worth the effort the restore, if not it goes to my salvage for parts.
Really a shame how sorry the Briggs OHV 31 and 33 series engines are made.
Briggs should be ashamed of themselves.
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Even if the standard leakdown test is done correctly it will not show a tapered,oval, or both cylinder problems this why a modified version must be done.
Also the heads do warp.
Also the heads do warp.