oil dripping from vent tube coming off check valve in oil line from remote tank to reservoir

[doctorchuck]

Noticed oil in water outside my 175HP Mariner. Pulled the cover and quite a bit of oil pooled in the housing. Started the engine and noted a frequent drip of oil from the vent tube. Took off the in line check valve, put some carb cleaner thru it , dried it out, put it back together and still leaking from the vent tube when the engine is running. Engine runs fine. Thoughts? Do I just need to replace the check valve, I believe it is a 2 or 4 PSI valve. Anything other than a faulty check valve cause this to happen?

 

[Faztbullet]

Pressure check valve that supply air to oil tank not bleeding off. In 40 years only seen 1 of these bad..

 

[doctorchuck]

Thanks for weighing in. Would anything other than a faulty valve cause oil to drip from the vent tube? I did some more research and it is a 4 PSI check valve. They are not widely available. Is there a way to clean it better than w/ carb cleaner squirted in? Should I just find one somewhere and replace it? Any thoughts appreciated.

 

[Faztbullet]

I doubt its the valve and its doing it job. The likely culprit is the pressure fitting on engine block that supplys air pressure to boat oil tank. It has a small hole that bleeds pressure off when engine is at rest. if oil tank overpressures the check valve will open and the result is what you are seeing.

 

[doctorchuck]

I doubt its the valve and its doing it job. The likely culprit is the pressure fitting on engine block that supplys air pressure to boat oil tank. It has a small hole that bleeds pressure off when engine is at rest. if oil tank overpressures the check valve will open and the result is what you are seeing.

So, help me understand how it all works. The crankcase pressure pushes oil from the remote tank up to the reservoir on the engine. Does the crankcase check valve just prevent the pressure to the remote tank from being more than ?2or4 PSI, or is it the opposite and it maintains the pressure at 2 or 4 PSI even when the crankcase pressure is lower than that? I really appreciate you educating me on this. Is there a way to test that crankcase check valve? Blow in one side or the other? Should be resistance 1 way, right? Or, should I just replace it? Thx again for your patience and help.

 

[Faztbullet]

Just replace it...

 

[doctorchuck]

Just replace it...

OK, I'll order the crankcase check valve. Will let u know if it fixes it. Appreciate the advise.