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Has anyone ever had this problem. I have a Briggs and Stratton OHV 15 Hp that runs great except under a load PTO engauged and driving oil comes from breather hose to airbox and runs back into carb and causes it to smoke under load. Not sure why it does this?
 

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Has anyone ever had this problem. I have a Briggs and Stratton OHV 15 Hp that runs great except under a load PTO engauged and driving oil comes from breather hose to airbox and runs back into carb and causes it to smoke under load. Not sure why it does this?


i would check the crank case vent ...Its building presser in the base could be over full with oil also
 

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The first thing that I would check is the breather,a blown headgasket won't cause excess crankcase pressure,worn rings would but the breathers job is to stop the oil and only allow crankcase emissions to get to the carb to be reburned.If it's only smoking under load,it's a good possibility that the rings and or cylinder are getting some wear,if it's not smoking to a point of killing bugs or using a lot of oil,it should go for a while yet.
 

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...a blown headgasket won't cause excess crankcase pressure...
I'm not familier with a Briggs and Stratton OHV 15 Hp engine to say for certain, but if the valve pushrods run through the head gasket, a blown head gasket can pressurize the crankcase. I suspect worn rings though.
 

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Jersey Mechanic
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The first thing that I would check is the breather,a blown headgasket won't cause excess crankcase pressure,
Please explain how a blown head gasket between the cylinder and valve galley (the most common place that they blow) on an OHV engine WILL NOT cause excess crankcase pressure?

To the OP, 90% of the time it is a blown head gasket on that OHV engine, rarely you will see a plugged breather, if you remove the air filter and watch the vent hose as you run it, if it is pushing oil through that hose, you have a blown head gasket.

Dan
 

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Please explain how a blown head gasket between the cylinder and valve galley (the most common place that they blow) on an OHV engine WILL NOT cause excess crankcase pressure?

To the OP, 90% of the time it is a blown head gasket on that OHV engine, rarely you will see a plugged breather, if you remove the air filter and watch the vent hose as you run it, if it is pushing oil through that hose, you have a blown head gasket.

Dan
that is where the head gasket will usually leak, good news is it's easy to replace.
 

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like i said before i would check the vent IE..the breather . is the air filter clogged with crap if i t is it will case a suction and suck the oil in to the carb .when was the last oil change is it over full ..
 

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If enough oil is coming through the breath tube it can oil soak your air filter and that doesn't help the motor to get enough air. Try washing out the breather and check oil level. then see what happens, maybe a simple fix.

I`ve had people push their mower over to me asking me I hit something and I changed the blade and now it wont start. first thing I look at is the air filter and it`s oil soaked, I remove the air filter and it starts right up. I tell them they tipped it over the wrong way, that is why its oil soaked.:fing20:
 

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Id check the head gasket. Pull the valve cover off put the cylinder on copression stroke and put 100 psi to it and look for a leak. You are going to have to find a way to hold or keep the crank from moving. A cylinder leak tester is what I use. a old spark plug with a air fitting welded to it will work..
 

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DITTO Blown Head Gasket
 
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