3.0L valve cover vent

[Kessi]

OK, so I'm not a total dummy with an engine, fact is I work with all kinds in many fields but I have to question the engineering behind my 1994 mercruiser 3.0L valve covers vent.
I have seen them with or without a tube running to the flame arrester (mine dose not have one) but there doesn't seem to be anything to prevent the oil vapor from simply blowing out the vent hole and getting all over the place.
Is there something that should be on the inside of the valve cover to prevent this, or at least reduce it?
If not is there any kind of modification anyone has come up with to deal with this?
Talked to a couple of techs and they just shake their head and say welcome to the boating world.

 

[Don S]

Re: 3.0L valve cover vent

It should still have a hose to the flame arrester. Probably just a couple of pieces missing.

http://dougrussell.com/partscatalog...10,19,11,16,15,17,20,26,12,24,25,18,2,3,4,1,8

 

[Kessi]

Re: 3.0L valve cover vent

Don,

I have the 23A set, doesn't have the tube or connector to the flame arrestor, and in any case if it did I would still have quite a bit of oil vapor coming out.

 

[Don S]

Re: 3.0L valve cover vent

if it did I would still have quite a bit of oil vapor coming out.

The oil vapor only comes out of the engine when it's running. When it's running, the air is sucked into the carb thru the flame arrestor. Which the hose is very close to and the vapors go into the carb.
It's been working for a LOT of years on a LOT of diffrerent boats.

 

[Kessi]

Re: 3.0L valve cover vent

OK, I fully understand the principals with the system that they have, not to mention how an engine/fuel system operates. My questioning is the amount of oil that is being dispersed through the vent.
I am used to PCV valves or a suction plate at the base of the carb, not a direct (which again, I have seen with and without the tube connection to the flame arrester) to the outside where it would possibly cause a buildup.
Even my older engines that vented direct to atmosphere had a course filter to trap the oil vapor in the filler cap.
True to point, the flame arrestor my have been replaced and the one I have now is incorrect (just bought the boat) and I fully accept that the system works, just wanted to know if there is a way of reducing the actual amount of oil that is being discharged through the system, and I mean the whole engine compartment is covered with a fine layer of oil, thought it will keep things from getting corroded
Thanks Don for your help and the parts diagram

 

[Don S]

Re: 3.0L valve cover vent

just wanted to know if there is a way of reducing the actual amount of oil that is being discharged through the system,

Rebuild the engine! If there is that much blow by, it must be wore out.

 

[Kessi]

Re: 3.0L valve cover vent

10 Hrs. on professional rebuild, not a fly by night or backyard job. No operating or power issues at all.

 

[Alumarine]

Re: 3.0L valve cover vent

Mine is 35 years old and I've never had any oil mist issues.

I know I've inspected the flame arrestor but I don't recall having to clean it.

 

[cheburashka]

Re: 3.0L valve cover vent

If it's hooked up correctly, there won't be any mist problems since the mist is drawn into the intake. It may oil up the flame arrestor, but I think that's part of the design. I've had a lot of smaller engines that used an oil-impregnated mesh air cleaner.

It seems that the OP's problem is related to the fact that there are parts missing from the fa assembly, allowing the mist to fly around the engine compartment. Hook it up right, and the problem is solved.

 

[NautiDog]

Re: 3.0L valve cover vent

Don S.,

I have the rubber tube that runs to the spark arrestor, but it keeps vibrating off of the valve cover. I have attached a clamp and it is tight enough that I can not pull it off, but it still manages to become loose as the engine heats up and runs. How critical is it that I leave it attached to the valve cover or is it alright to be left off loose. I am getting a little oil misting on my engine compartment cover.

Thanks.

 

[JustJason]

Re: 3.0L valve cover vent

I've never seen them pull off easily unless they the hoses are 100 years old...
replace the hose and glue it in place with some perfect seal... and then clamp it if your having that many issues....

 

[NautiDog]

Re: 3.0L valve cover vent

Thanks, I will apply some glue on it and reclamp it.