oil comming out of crank case breather

R

rocky4

Active Member
Joined
Jul 16, 2014
Threads
23
Messages
71
I have a B&S 331707 0115-B1 17.5 HP engine. Has oil being blown out through crank case breather passage. No blue smoke coming from exhaust.
Oil is not over filled and does not smell of gas. Removed breather passage assy and was full of oil. The reed is in place. Any help?
Thanks in advance
 
gfp55

gfp55

Well-Known Member
Joined
Mar 13, 2014
Threads
23
Messages
860
rocky4 said:
I have a B&S 331707 0115-B1 17.5 HP engine. Has oil being blown out through crank case breather passage. No blue smoke coming from exhaust.
Oil is not over filled and does not smell of gas. Removed breather passage assy and was full of oil. The reed is in place. Any help?
Thanks in advance
Click to expand...

Is the reed valve working correctly. Did you have the mower tipped up like when cleaning the bottom or changing/sharpening the blade. If yes, sometimes the oil will fill the breather passage with oil and blowby will blow the oil out when the engine is run. Keep us posted.
 
R

rocky4

Active Member
Joined
Jul 16, 2014
Threads
23
Messages
71
gfp55 said:
Is the reed valve working correctly. Did you have the mower tipped up like when cleaning the bottom or changing/sharpening the blade. If yes, sometimes the oil will fill the breather passage with oil and blowby will blow the oil out when the engine is run. Keep us posted.
Click to expand...

Thanks for replying
This is a murray riding mower. I just finished rebuilding the motor.Had to replace the piston and rod. I looked at the reed,looks ok but not sure what to look for in way of not working. Motor runs great and has 80 lbs pressure. What is the purpose of the reed and how does it work? Could a bad piston ring cause this problem?
 
gfp55

gfp55

Well-Known Member
Joined
Mar 13, 2014
Threads
23
Messages
860
rocky4 said:
Thanks for replying
This is a murray riding mower. I just finished rebuilding the motor.Had to replace the piston and rod. I looked at the reed,looks ok but not sure what to look for in way of not working. Motor runs great and has 80 lbs pressure. What is the purpose of the reed and how does it work? Could a bad piston ring cause this problem?
Click to expand...


80 psi seems kinda high, if the oil pressure is too high and the reed valve is only good to 60-65 psi then you will get oil coming out the breather. What is the max oil pressure for that engine? What are the specs for that engine? Yes a bad ring will cause blowby and high oil pressure, because gases are leaking passed the rings into the crankcase. Does the engine have a fuel pump? If yes what type?
 
M

Mikel1

Well-Known Member
Joined
Jul 21, 2013
Threads
10
Messages
897
rocky4 said:
What is the purpose of the reed and how does it work? Could a bad piston ring cause this problem?
Click to expand...

The breather valve aka reed maintains crankcase pressure. On piston up stroke closes and on piston down stroke opens.
Did you reuse the old rings?
 
R

rocky4

Active Member
Joined
Jul 16, 2014
Threads
23
Messages
71
Mikel1 said:
The breather valve aka reed maintains crankcase pressure. On piston up stroke closes and on piston down stroke opens.
Did you reuse the old rings?
Click to expand...

Yes, I did use old rings.
 
R

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
55
Messages
14,763
Did you make sure that the ring end gaps were 120 degrees apart when you installed the piston. If the end gaps were near each other, that would create a lot of blowby and be the cause of your problem. Also, did you check the end gap before installing them on the piston. If they are too large, that would be another cause. This is an overhead valve engine, did you replace the intake valve seal? Could also be a blow head gasket. Too many possibilities. This is going to make you into a detective to solve this one.
 
R

rocky4

Active Member
Joined
Jul 16, 2014
Threads
23
Messages
71
gfp55 said:
80 psi seems kinda high, if the oil pressure is too high and the reed valve is only good to 60-65 psi then you will get oil coming out the breather. What is the max oil pressure for that engine? What are the specs for that engine? Yes a bad ring will cause blowby and high oil pressure, because gases are leaking passed the rings into the crankcase. Does the engine have a fuel pump? If yes what type?
Click to expand...

I really don't know what the specks are. Has no fuel pump. Its a B&S, 17.5 ohv, 331707 0115-B1 engine.
Does anyone know what the compression should be on this engine?
 
gfp55

gfp55

Well-Known Member
Joined
Mar 13, 2014
Threads
23
Messages
860
rocky4 said:
I really don't know what the specks are. Has no fuel pump. Its a B&S, 17.5 ohv, 331707 0115-B1 engine.
Does anyone know what the compression should be on this engine?
Click to expand...

If I were you I would get a service/shop manual for your engine. I don't want to insult you but if you are going to "rebuild" an engine you don't reuse rings. A engine service/shop manual will give you a step by step run down to correctly rebuild an engine. It will have all the info you will need. Did you reuse the head gasket? Did you torque the head bolts in the correct order? I see others are helping you also now.
 
You must log in or register to reply here.

Footer Links 1

Top