The engine turn over when you pull on starting rope. It idle smoothly. Then you get whiff of oil mixed with raw gasoline.
There’s a growing dark puddle under the mower deck. No, it didn’t leak during refueling time. Something’s wrong with your Briggs and Stratton engine: The crankcase sealing system have broken.
Oil weep upward into air filter housing. Sometimes it soak the filter. Other times, it mix with fuel vapor.
That’s a fire hazard. The paper filter get ruined, too. Worse yet, it signal that there’s no longer adequate internal pressure.
Fix it now; otherwise, the problem will only gets worse. Early action is often cheap. The number one reason for crankcase pressure are an improperly sealed oil fill tube.
How to Fix Oil Leaks on Briggs Engines
Signs of Crankcase Sealing Failure
This rubber gasket is located at the end of dipstick as it extend into engine block. Over time the chemicals and heat will crack and harden the rubber. When the seal fail, crankcase pressure push oil up.
Since this is air pressure, it take path of least resistance. In many cases that are the air cleaner assembly. It is a small but significant piece of equipement.
Replacing the rubber seal is cheap insurance and eliminates the leak. Obtain proper part for your model. Next up is valve cover gasket.
Fixing the Oil Fill Tube Gasket
Since these engines runs hot, the valve cover gasket located between the valve cover and cylinder head will deteriorate. When it do fail, you has oil leaking down side of engine. That oil collect in crevices which then feed back towards intake.
It’s not as easy to diagnose because it show up on outside of engine. What you notice is there’s wetness on top of engine. Just clean it out and install a new gasket and done.
It takes a little more patience different than replacing the fill seal, but it is same principle. A broken seal isn’t always the issue. First off, check your oil level.
Replacing the Valve Cover Gasket
If you overfill crankcase, the pressure would of have nowhere to go but up! The crankcase breath in order to equalize the pressure. And when it’s full to the brim, that breathing action cause oil to push out any way it can.
One of those ways are the air filter intake. Is the dipstick overfull? Drain some.
Better to drain too much oil then to have to replace seals you didn’t need. Another factor is air filter maintenance. A dirty air filter reduce airflow.
Checking Oil Levels and Air Filters
Reduced airflow cause an increase off pressure/ vacuum differential inside engine. This further impede ability for engine to breathe, making even small leaks worse. Before you pull the seals apart change the filter.
It is cheap insurance. A filter caked in oil or grass mean the engine has to work harder than it should. And that show up in ways you might not expect.
And then there’s the breather hose. It is a little tube that run between your air cleaner and valve cover. What does it do?
Inspecting the Breather Hose
It let the air equalize. When your breather’s hose is clogged with sludge, loose or even has a crack in it, air pressure build in crankcase. And what does it do when it can’t get out?
It push oil past any weak points it finds. Check your hose for damage. A brittle or kinked hose are simple to fix.
Just replace with new one you pick up at the shop. Keeps the oil where it needs to be and vents properley. If you have an oil leak on your Briggs and Stratton mower, take a deep breath, then diagnose and fix it.
You don’t need to run out and purchase a replacement engine. First check: fill seal, then valve cover, then oil level, and finally the breather hose. Chances are it’s just a minor bit of oil being over-filled and/or a tiny gasket.
Mower runs like a champ again. Burnt oil smell dissapears.