# Briggs and Stratton



## treystevens57 (Aug 31, 2014)

My Briggs and Stratton 16.5 twin is shooting oil out of the hose that goes into the air filter box and I can't figure out how to fix it can anyone help please


----------



## GTcollector (Dec 27, 2010)

treystevens57 said:


> My Briggs and Stratton 16.5 twin is shooting oil out of the hose that goes into the air filter box and I can't figure out how to fix it can anyone help please


That would indicate you have high oil pressure in the crankcase, that could indicate blow-by caused by bad rings or valve guides, either way it probably means an engine tear down.


----------



## treystevens57 (Aug 31, 2014)

GTcollector thank you I'll have to look into that any extra info on where to go into the motor at


----------



## jhngardner367 (Apr 5, 2011)

You have a blown head gasket,and it's pressurizing the crankcase.


----------



## GTcollector (Dec 27, 2010)

jhngardner367 said:


> You have a blown head gasket,and it's pressurizing the crankcase.


Not sure how a blown head gasket pressurizes the crankcase, wouldn't the air escape out between the head and cylinder? It would seem that since the piston travels upwards toward the top of the cylinder, it would force air out the bad gasket, and not the crankcase, any air allowed into the crankcase could only come from bad valve guides or bad rings, but again, still wouldn't a leak between the head and cylinder allow the pressure to escape there just as much as anywhere? I'm not saying your wrong, I just need some clarification on why. I've never seen a blown head gasket on a car pressurize a crankcase either, but I've never owned a Chevy.


----------



## phogbound (Jan 16, 2012)

Is the oil level too high? Was the dipstick changed - too short? If any air leaks into the crankcase, the air goes out the breather and takes oil with it. Check the seal on the dipstick and the crank seals. They might not leak oil out but leak air in. The breather might be bad and not control the crankcase vacuum. If it is an overhead valve engine, it could have a leaking head gasket(s).


----------



## phogbound (Jan 16, 2012)

*On a header*



GTcollector said:


> Not sure how a blown head gasket pressurizes the crankcase, wouldn't the air escape out between the head and cylinder?
> 
> On an overhead valve engine, the thinnest and least supported part of the gasket is between the combustion chamber and the push rod chamber. If the gasket develops a leak there, combustion gas enters the crankcase.
> I own a Ford and it had a head gasket leak. Combustion gas entered the cooling system when it was running and coolant leaked into the combustion chambers when it was shut off. That was an expensive repair and a very common Ford V6 problem.


----------



## GTcollector (Dec 27, 2010)

phogbound said:


> Is the oil level too high? Was the dipstick changed - too short? If any air leaks into the crankcase, the air goes out the breather and takes oil with it. Check the seal on the dipstick and the crank seals. They might not leak oil out but leak air in. The breather might be bad and not control the crankcase vacuum. If it is an overhead valve engine, it could have a leaking head gasket(s).


So overhead valve engines with blown head gaskets pressurize the crankcase? and non OHV engines do not, or they do? Can any one tell me why? Thanks


----------



## jhngardner367 (Apr 5, 2011)

Flat head engines don't ,because the valves are the only area that lead to the crankcase ,and the breather is located BELOW the level of the leak.
With the OHV,there is a pushrod passage from the crankcase,right up through the head . There aren't any cylinder head bolts in this area,and this is the weakest spot on the gasket. As the engine runs.gasses flow out,and go through this passage,and pressurize the crankcase .
At the same time,each time the intake draws fresh fuel/air mix in,it also sucks in oil ,and causes smoking .
Since the flat head doesnt have this passage,the pressure is pushed outside the engine case.


----------



## GTcollector (Dec 27, 2010)

jhngardner367 said:


> Flat head engines don't ,because the valves are the only area that lead to the crankcase ,and the breather is located BELOW the level of the leak.
> With the OHV,there is a pushrod passage from the crankcase,right up through the head . There aren't any cylinder head bolts in this area,and this is the weakest spot on the gasket. As the engine runs.gasses flow out,and go through this passage,and pressurize the crankcase .
> At the same time,each time the intake draws fresh fuel/air mix in,it also sucks in oil ,and causes smoking .
> Since the flat head doesnt have this passage,the pressure is pushed outside the engine case.


So it's a good guess, the posters engine is a OHV, because it's a 16.5hp (didn't see the .5 at first). Makes sense now. I have 12 kohler Kseries, 2 Briggs CI singles, 1 Tecumesh, and 1 Wisconsin, not really versed at all in late model OHV engines or Chevy's (lol) Thanks for 'splainin it to me. Just wondering if the head gasket is good what might it be?


----------



## jhngardner367 (Apr 5, 2011)

Plugged crankcase breather,or too high of oil level,or timing.


----------

