Oil spewing out of breather tube !!!

[floridafishing]

2005 250hp Yamaha runs great , at 3000/3500 rpms spews oil out of breather tube , been to certified shops can't find issue . Passed leak down test , changed oil pump , can't find problem need help !

[floridafishing]

can someone help me???

[boscoe99]

2005 250hp Yamaha runs great , at 3000/3500 rpms spews oil out of breather tube , been to certified shops can't find issue . Passed leak down test , changed oil pump , no oil on plugs , can't find problem need help !

I am presuming this is an F250 (four stroke) and not a 250 (two stroke) Yamaha.

Blow by out the breather tube generally indicates a worn cylinder and/or piston rings.

A leak down (sic) differential pressure test can be a teat on a boar hog.

Think about it. With a differential pressure test the piston rings are at the upper most part of the cylinder. Where the wear in the cylinder will be the least. The rings may be sealing just fine there, but not sealing so well at all of the areas of travel down below.

Perhaps the cam shafts need to be removed so that all valves remain closed while another differential pressure test is performed with the piston somewhat down into the cylinder.

Or, maybe a bore scope should be sent down the spark plug hole to check the condition of the cylinder walls. Maybe one or more is scored down below which might not effect a top dead center differential pressure test.

Where the hell is rodnut?

[pstephens46]

No oil on plugs?

[pstephens46]

Hopefully Rodbolt is not meeting with Evan again?

[fairdeal]

2005 250hp Yamaha runs great , at 3000/3500 rpms spews oil out of breather tube

I'm puzzled. I'm not picturing what the "breather tube" IS -

much less, how one would see what it is doing at 3000 rpms

[TownsendsFJR1300]

Piston ring blow by, worn rings..

The crankcase is being pressurized by compression from the top end blowing oil out..


Had it on a dodge slant 6 that would blow 5 quarts out the dip stick hole in 10 miles.. Rings had an end gap of about 1/4". A new set of rings, it was just inside spec's. BIL drove the car for many years after that..

[robert graham]

If this is a 4 stroke motor doesn't the crankcase have some type of ventilation valve or line????

[pstephens46]

Maybe he can tell us what he refers to as breather tube? Or has he disappeared?

[TownsendsFJR1300]

If this is a 4 stroke motor doesn't the crankcase have some type of ventilation valve or line????

Same thing. Should be venting into the air intake (for re-burn & emissions)

[boscoe99]

[robert graham]

Would a malfunction of this system give the OP his oil spewing problem?...seems like this system would be a good place to start checking?...

[boscoe99]

Would a malfunction of this system give the OP his oil spewing problem?...seems like this system would be a good place to start checking?...

I can't imagine how the system itself would malfunction. It is just a tube from the crankcase to the air intake.

I am guessing the oil is being spewed out of the breather tube and into the air intake system and causing the motor to run like crap and/or making a mess of the throttle valve. So much gas is escaping so quickly that the air/oil separator function of the motor cannot do its job.

Reminds me of '62 Ford Falcoon I once had. Every time I stopped in traffic I was surrounded by billowing exhaust smoke. To minimize my embarrassment I tried routing the breather hose to the intake but it made a mess of the carburetor in short order. Damn those were the good ole days.

[robert graham]

Maybe tube is plugged up, cracked, broken?....just thinking....

[zenoahphobic]

Maybe tube is plugged up, cracked, broken?....just thinking....

It wouldn't then blow oil!

Go with worn ring/bore until proven otherwise. Which cylinder and how? The OP's certified shops should be uncertified!