# Briggs and Stratton burning oil



## billick01

Hi,
I have a ride on mower with a 17HP Briggs and Stratton Intek OHV engine.
The mower is 10 years old.
Earlier this year, prior to the start of the cutting season I replaced oil, oil filter and air filter. Oil (SAE30) was filled to the correct level.
During the second cut of the year, whilst mowing up a short slope, (10 yards long), the exhaust blew out a lot of black smoke. I got the mower to a level section and let it cool down. It started OK, with no repeat of the smoking incident.
However, over this cutting season I have noticed oil is getting burnt, and I am having to top up every cut.
The engine pulls well and does not falter.
I have checked the rubber breather tube between air filter and breather unit and it is not blocked.
I removed the breather valve on the side of the engine and checked that there is no blockage from the breather valve mounting recess into the crank case.
The spring loaded valve in the inner face of the breather does open when light air pressure is applied. 
After reassembly, the engine is still burning oil.
Should I replace the crank case breather assembly, or is it rings or blown head gasket?.


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## kjms1

Its NOT the head gasket 
doesnt that breather valve have a hose hooked to it that goes to the upper part of the engine and gets vaccum


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## billick01

Thanks for the quick reply.
This is how the breather valve is connected.
Starting at the air filter housing, there is a rubber hose that connects from the air filter housing to the top of the breather valve unit. The breather valve unit is rectangular in shape and bolts directly onto the side of the crankcase by (2) screws.
The rubber hose is not blocked.
When you remove the two screws and take off the valve and its gasket, there is a rectangular recess in the side of the crankcase. 
There are two holes in the recess. One hole (small) is in the bottom right hand corner of the recess, and the the other (large) is in the top right. Both of these holes feed into the crankcase. I checked with some flexible twine that these are not blocked.
I checked the breather valve operation by first pressing on the spring loaded valve that is on the face of the valve unit that goes into the recess. I also blew gently on it to ensure it opens. It is a very light spring.
I did run the engine with the air filter and the housing removed so I could see where the crankcase vapours come into the intake of the carb. There was oil vapour being emitted.
Either the breather valve unit is faulty, or something is generating excessive crankcase pressure.
Note that this has happened since the short (and I do mean short) uphill incident with the excessive smoke I experienced earlier in the year.


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## kbowley

If it were me, I would purchase a breather kit as they are cheap. New reed valve, sponge, seals and gaskets...maybe 20 bucks. However, i wouldn't get my hopes up as this is most likely not the cure. Based on your statement that you could see that the breather is exhausting visibly, that means blowby at the rings. However, i wouldn't let it bother me...just run it and add the oil as needed. If it gets so that the engine is visibly smoking out the exhaust after warming up, I would simply look on Craig's List for a trusty 12 HP I/C flathead briggs. They run forever, produce as much torque as the 17 HP OHV and it would drop right in. You can usually find those for 100 bucks or so. If you choose, you can purchase a new replacement for around 450.00.


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