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Valve Cover Breather Question?

1160 Views 19 Replies 6 Participants Last post by  SweetEmotion
I recently noticed my bilge was full of that milky water oil mixture. Couldnt find where it was coming from so I took it in. My guy said the automotive breather I installed with a foam filter had clogged up creating pressure. He pulled out the dipstick and said oil was coming out. Does this sound right? If so is there a bigger problem brewing because of this pressure. Note I only ran a few times before I noticed the oily bilge.
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Do you run a PCV valve?Crankcase pressure can push oil out the seals.
Is the oil in the motor milky?
If it is then you have a water leak and when you drove the boat and got the oil/water mix above the boiling point it blew out the dip stick.
No pcv valve
No lucky the oil inside the motor clean
I've never once had a breather clog up. Not on my boat nor my race cars. If one breather is clogged where your other valve cover port going too?
What Im understanding is there is a difference between auto breathers and marine breathers due to a foam filter in the auto breather.
I didnt know that. I just run a cheap Breather from Autozone and a PCV valve which is ran to a modified port on my Edelbrock Marine carb. No issues , no condensation, no nothing.
See I have no pcv valve. I was told the condensation I had which helped clog the foam filter is a result of my engine not getting hot enough to burn up that condensation.
I had same problem. Thats why I added a PCV. Now, with just hoses running to the flame arresotr you should have no problems.
You mean forget breather altogether and run a hose straight from covers to arrestor?
Thanks for the info, I ll let ya know how that works out
You need some type of crankcase ventilation or you will blow oil out of the tube and/or seals.

The factory setup (older) doesn't use a PCV valve and has hoses connected from the valve covers to the flame arrestor. The vacuum created by the air rushing into the arrestor during high-speed operation is enough to pull the air (and reduce pressure) in the crank case.

When switching to a larger flame arrestor or eliminating the hoses, there is no longer vacuum to pull vapors and reduce pressure, and then you end up with a mess.

You can keep the nice open element breather, but add a PCV valve to the other valve cover. You will be fine from there.
Sweet, these are what you want:

The bretahers have internal baffles to stop oil from blowing out.

You will find them on most of the well known engine builders engines.

Crank case pressure is normal and allot of the automotive type breathers and K&N breathers will collect oil in the mesh/filter element. When they are full the crank case pressure blows the oil out. They are meant to breath air, not oil. If your valve covers do not have baffles under them the problem is even worse.

Some people even go as far as puke tanks to collect the oil. Others will have problems with oil blowing out of the dip stick tube. One of the above on each valve cover will solve the problem.

It sounds like your oil is clean, so I doubt you have heating/cooling issues. Most motors will show small signs of milky oil on the underside of the valve covers since the engine heat dissipates before getting to the top of the valve cover (especially aluminum) As long as your engine gets to or above 145deg. when running, you are fine.
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Thanks Twin I was hopping to hear from you. You always have the answers to my questions. I did buy a new larger flame arrestor too. This all makes alot of sense now
I noticed a loss of a few mph could this be a reason why? I was doing 60-61 now 57 :confused:
Are you gonna be on the river this weekend? We may come down to the gravel pits late sat. afternoon and party there for the night. If not then we may run down on Sun.

Not sure on the speed...It could be, but I would think weather conditions might be the culprit since it has been warmer and much more humid than the past weekends.

See Ya!
Weather doesnt look all that great, now I gotta run to Detroit to pick my boat up. Thats where the engine buliders located he warrantied it for me I called him with concerns that it was a rear main so he came and picked the boat up last Wed. Called yesterday to tell me oil came from my dumb a**, all in all he didnt sound happy hopefully I dont get stuck with a gas bill :confused1

Im planning on getting it Friday night, just head out after work. If Saturdays nice I`ll see ya out there.
Ut Oh!

How did it come from you?

Sounds like a great warranty!
Because I put those wrong breathers on and the larger flame arrestor that created the problem.

I was very impressed with the builder backing his work enough to come get the boat. His name is Lenny he owns Millennyum Marine on Lake St. Clair. Cann`t say enough about those guys and their work.
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