Old Tecumseh Engine-oil coming out of overflow under load
 

I was just given an old Jacobsen Snowthrower. It seems to be a good old
workhorse but when it gets under a load it seems to blow oil out of the
overflow tube. I don't have a manual for it. But it is an old Tecumseh
engine...probably around an 8hp.
Any ideas as to what might cause this?

Thanks in advance,
tom

Old Tecumseh Engine-oil coming out of overflow under load
 

TomM in NY wrote:

I was just given an old Jacobsen Snowthrower. It seems to be a good old
workhorse but when it gets under a load it seems to blow oil out of the
overflow tube. I don't have a manual for it. But it is an old Tecumseh
engine...probably around an 8hp.
Any ideas as to what might cause this?

Thanks in advance,
tom



Assuming you haven't filled it with beyond it's capacity, then:


It sounds like a lot of "blowby" from the combustion chamber around the
piston and into the crankase. Could be just stuck piston rings, but more
likely it's wear on the cylinder bore.

It's not really economical to pay someone else to repair a worn out
single cylinder engine these days. You can buy a whole new engine for
under $300 if you shop around.

Jeff

--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone
to blame it on."

Old Tecumseh Engine-oil coming out of overflow under load
 

The other fellow had some good ideas. Namely to pull the dipstick and see if
the engine oil is over full. Total system capacity is some where around 16
to 20 ounces. Might want to drain it and change the oil anyway.

Let me add one more option.

It's been awhile since I worked on a Tec 8 HP. But.... on the same side of
the engine as the carbeurator should be a small access plate, about an inch
high and three inches left to right. It is held on with two bolts which are
tiny (1/4 or 5/16 nut driver). There may possibly be a small tube which goes
from this plate, to the air intake.

This "plate" is a check valve. It is designed to allow air out of the
crankcase, but not allow it back in. So when the piston is going up and
down, the crankcase can operate at a very slight vacuum, but not under
pressure. Sometimes these check valves get dirty,a dn they don't work right.

Take the valve off, and spray it out with carb cleaner, or maybe soak it in
gasline and very gently brush the crud off of it. Put it back (careful,
there is usually a gasket under the plate,a dn the gaskets are usually dried
and brittle). See if that helps.

--

Christopher A. Young
Join Alt-Hvac Moderated
A free, easy to use Yahoo! group



"TomM in NY" wrote in message
...
I was just given an old Jacobsen Snowthrower. It seems to be a good old
workhorse but when it gets under a load it seems to blow oil out of the
overflow tube. I don't have a manual for it. But it is an old Tecumseh
engine...probably around an 8hp.
Any ideas as to what might cause this?

Thanks in advance,
tom

Old Tecumseh Engine-oil coming out of overflow under load
 

It's been awhile since I worked on a Tec 8 HP. But.... on the same side of
the engine as the carbeurator should be a small access plate, about an inch
high and three inches left to right. It is held on with two bolts which are
tiny (1/4 or 5/16 nut driver). There may possibly be a small tube which goes
from this plate, to the air intake.

This "plate" is a check valve. It is designed to allow air out of the
crankcase, but not allow it back in. So when the piston is going up and
down, the crankcase can operate at a very slight vacuum, but not under
pressure. Sometimes these check valves get dirty,a dn they don't work right.

Take the valve off, and spray it out with carb cleaner, or maybe soak it in
gasline and very gently brush the crud off of it. Put it back (careful,
there is usually a gasket under the plate,a dn the gaskets are usually dried
and brittle). See if that helps.


that's a briggs. techumseh had a seperate breather . if the breathe
got plugged anyway it would blow a crankcase gasket or seal.
what the OP has is a worn out motor.
Chip

Old Tecumseh Engine-oil coming out of overflow under load
 

Whoops! Like I say, it's been a while. Thanks for catching my misteak.

--

Christopher A. Young
Join Alt-Hvac Moderated
A free, easy to use Yahoo! group



"Chip Stein" wrote in message
om...

This "plate" is a check valve. It is designed to allow air out of the
crankcase, but not allow it back in. So when the piston is going up and


that's a briggs. techumseh had a seperate breather . if the breathe
got plugged anyway it would blow a crankcase gasket or seal.
what the OP has is a worn out motor.
Chip

Old Tecumseh Engine-oil coming out of overflow under load