Oil coming out of Breather on 4cy 3.0. Is this normal?

[Redphone107]

Hey there. another quick question. I have a 2004 mercruiser 3.0 with the 90 degree breather elbow on the valve cover. I have noticed that after running the motor all day at the lake pulling the kids on the tube that there is a small amount of oil blowing out of the breather. Does anyone else's motor do this? It looks like there is a place on the elbow to hook up a hose. Is there suppose to be a hose on it? And if so, where would the other end connect? I didn't see anything on the parts diagram about a hose. I have checked the oil and it is not overfilled. Thanks.

 

[Bt Doctur]

there usually is a hose directing it to the flame arrestor

 

[888]

Very little oil blowby is normal but excessive blowby is usually signs of a bad cylinder. Time to get the compression tester out

 

[RaceCarRich]

Mine has the hose to the flame arrestor and does leak a little around the vc grommet. Not enough to worry me but more than I would like.

 

[stonyloam]

21 here should do it, but check with dealer : https://www.mercruiserparts.com/Sho...r=2330&bnbr=60&bdesc=Fuel+Pump+and+Carburetor

 

[Redphone107]

Thank you all. I don't think I explained very well. There is no oil near the carburetor. On the valve cover, there are two openings. One is the large opening with a cap. That is the opening for putting oil in during an oil change. The other opening is a rubber grommet with a plastic elbow that is a vent for the motor. Same as in car engine. Only with a car engine, a PCV valve is usually in place of the open vent that we have on the boat engines. The oil that I am seeing is coming from the breather vent to the motor, not the carburetor. Does anyone have a pipe that attaches to the motor vent elbow that keeps the oil from coming out.

 

[Viking62]

Yes. My 2008 has a hose from that fitting to the flame arrester on the carb as was mentioned above

 

[Redphone107]

Thank you viking62. Where on the flame arrestor is a fitting for the hookup. I will search the manuals for the fitting. thank you again. I didn't understand what you were saying before.

 

[Viking62]

It's like a tab on the side of the flame arrester that the hose fits over

 

[havoc_squad]

For peace of mind, get those cylinders compression checked. Excessive blowback is an early warning sign you don't want to ignore.

Just use an auto parts loan-a-tool program for their compression tester, all it costs you is a very small fee and some time.

1. Make sure ignition coil is unplugged from power
2. label each spark plug wire with white tape with the cylinder number.
3. Remove all spark plugs
4. Test each cylinder for 2 to 3 compression strokes.


I believe if the compression builds up dramatically after each compression stroke, that's likely piston rings.

If the compression remains about the same for each stroke, that could be another issue (valves, head gasket, etc.)

 

[Redphone107]

No Title

Viking62. I watched some youtube videos of these engines running and I see some that have a tab on the flame arrestor. The pipe, about 3/4 inch dia., attaches to it. My arrestor does not have that. Others just had an "L" shaped hose coming off and angling straight up. I guess that is what I need. Just so that oil that jumps around in the valve cover does not come out. I have attached a photo of the breather tube (90 degree elbow). The way it is in there, it sits really low and no wonder oil is coming out.

Havoc. I have a compression tester, but I have a little problem. Plug hole number 4 was stripped out by the previous owner. He re-tapped it and put a spark plug insert into the hole and then the plug into that. I replaced the sleeve and plug recently and used red RTV between the sleeve and new tapped hole. Problem is that if I pull the plug again, I'm sure the sleeve will come out with it even though it is not suppose to. I have checked the hole for leaks and it is sealed now. Those sleeves are like $12 and a pain to thread and insert. I will start by testing compression on cylinders 1-3 and if they all look good, then I will get a new sleeve insert and pull the old on and try to test that cylinder. Thanks for the advice on the compression. Fingers crossed that its not a matter of compression. That would be really bad.