Universal engine mod that may help keep oil out of your bilge

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Ryan L

s/v Naoma
Here's an experiment I've been doing for the past year that has turned out well so far...

On our E38-200 there was a crankcase breather hose (I think that's what it's called?) leading to the bilge. Over time it would collect oil and drip it into the bilge. A mechanic friend of mine suggested re-routing the hose to the air intake (common on other engines.) I did that by drilling a hole into the aftermarket filter (see pic). This kept the oil out of the bilge but made the filter more oily than I liked. After a while I found some expensive filters designed to separate the oil from the crankcase air being recirculated back to the engine. They were generally used on larger engines. The experiment was to emulate those filters by attaching a simple sea strainer at the low point of the hose routed between the crankcase and the air intake. It seems to work! Much of the oil is collected in the strainer leaving a much cleaner air filter. The oil in this pic is the amount after around 100hrs of use.

P.S. Please forgive the rats nest of wires in the background. These pics are from last year and the wiring has since been mostly cleaned up... :)

As always I'm open and grateful for feedback, especially if it prevents some unforeseen catastrophe...

NOTE- Not sure why the forum rotated the pics 90 degrees. They are straight on my desktop.

photo-1.jpgphoto.jpg
 
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ref_123

Member III
Hi Ryan,

we did the same, but mostly due to smell of exhaust and not oil dripping.

Our M-25 drips oil from the rear seal - apparently worn out. However, fixing it turns out to be a major PITA (and expense), so mechanic told us to just live with it and replace oil rugs under the engine on a regular basis...

Regards,
Stan
 
Joliba

Joliba

1988 E38-200 Contributing Member
Another fix

Ryan,
What you've done looks good. Much nicer to have a closed system. I trust that the strainer you use is compatible with the temperatures and the oil there.. The Kubota people planned for their engines to run outdoors over land (though our engine blocks were only used in forklifts and marine conversions, never tractors.) They didn't mind a little "oily engine smell" or an occasional drip. I have not modified my breather pipe. I once discussed it with an excellent marine diesel mechanic who told me that many people insert the lower part of the tube into a container and attach it with some sort of sock and a hose clamp. I can see that this will contain and collect the oil, but it does not eliminate the odor. On some days, mine seems to spit out visible water vapor more than it drips oil.
Mike
 
R

Ryan L

s/v Naoma
Joliba said:
Ryan,
What you've done looks good. Much nicer to have a closed system. I trust that the strainer you use is compatible with the temperatures and the oil there.. The Kubota people planned for their engines to run outdoors over land (though our engine blocks were only used in forklifts and marine conversions, never tractors.) They didn't mind a little "oily engine smell" or an occasional drip. I have not modified my breather pipe. I once discussed it with an excellent marine diesel mechanic who told me that many people insert the lower part of the tube into a container and attach it with some sort of sock and a hose clamp. I can see that this will contain and collect the oil, but it does not eliminate the odor. On some days, mine seems to spit out visible water vapor more than it drips oil.
Mike
Click to expand...

More great feedback! I have no idea if the strainer is compatible with the oil/temp but so far there is no visible evidence of discoloration, distortion, etc. If I remember next time the engine is running I'll check the strainer temp with an IR thermometer. One of the 38-200s we looked at while searching for our boat had the sock-in-a-bottle set up. It was a mess and looked like someone was trying to find a quick fix to a mistake.
 
R

Ryan L

s/v Naoma
Christian Williams said:
Here's Maine Sail on the topic:

http://www.pbase.com/mainecruising/m25_air_filter__pcv_valve
Click to expand...


Great link! It gives me a lot of confidence knowing Maine Sail did pretty much the exact same thing... My first impression of the way he attached the hose is that it is more complicated (slightly) with the need to drill/tap and add an additional fitting but maybe by attaching the hose on the engine side of the filter you eliminate the "need" to capture the oil before it gets to the filter? Thanks for posting the link.
 
Joliba

Joliba

1988 E38-200 Contributing Member
More questions

Ryan,
Although simply rerouting the blowby from the crankcase into the intake makes a nice closed system, I wonder about it on this engine. Were the Kubota engineers just doing it the old fashioned way or is there a reason they did not reroute it? When I see water vapor or some other contaminated blowby coming out, do I want to shoot it back into my cylinders? I really do not know enough about it, but would enjoy talking with the Kubota engineers if my Japanese were better. Had you considered a filter such as this rather than a strainer? http://maesco.com/products/racor/r_ccv_intro/r_ccv_intro.html
Mike
 
R

Ryan L

s/v Naoma
Joliba said:
Ryan,
Although simply rerouting the blowby from the crankcase into the intake makes a nice closed system, I wonder about it on this engine. Were the Kubota engineers just doing it the old fashioned way or is there a reason they did not reroute it? When I see water vapor or some other contaminated blowby coming out, do I want to shoot it back into my cylinders? I really do not know enough about it, but would enjoy talking with the Kubota engineers if my Japanese were better. Had you considered a filter such as this rather than a strainer? http://maesco.com/products/racor/r_ccv_intro/r_ccv_intro.html
Mike
Click to expand...


Yes thank you, that filter was the inspiration for the sea-strainer mod. They cost around $200. I asked a trusted mechanic/friend and he explained that he did not believe there was a need for filtering the blow-by on our engine. Knowing that people as meticulous as Maine Sail also route the blow-by in a similar way definitely boosts my confidence. Ultimately maybe this is one of those times where you make your best guess and trust it pleases the engine gods?
 
jreddington

jreddington

Member III
There is a real danger with this setup. Anything connected directly to the intake will have at least a small amount of vaccuum sucking on your crankcase. This could suck oil vapors into the engine enough to keep it running even when you shut down the throttle.

I ran into this with my M-15 which is amazingly hard to get a consistent dip stick reading on. I ended up overfilled. This lets the crank dip into the oil and churn it, spraying out a lot of oil. When this happened engine kept running even when I yanked the throttle back as hard as I could. No good. Then, on instinct, even though my head knew it was the wrong thing to do, I shifted into neutral, which only led the engine to rev up. I did come to my senses a second after and threw it back into gear before it revved too much.

Then dived below and pulled the vent line from the area of the intake. There were spritzes of engine oil all over the place.

Make sure you don't overfill the crankcase and will probably not happen to you.

What I have done is run the vent hose parallel to the horn on my intake, ending at the lip of the horn. That way the end of the vent line is at ambient pressure with no suction running on it. However, vapors coming out can be sucked back in a U turn to minimze any odor.

If I get a chance I'll take a photo of it.

General advice.

NEVER overfill the crank case.
Place crank case vent outlet near engine intake but NOT connected directly.
 
R

Ryan L

s/v Naoma
jreddington said:
There is a real danger with this setup. Anything connected directly to the intake will have at least a small amount of vaccuum sucking on your crankcase. This could suck oil vapors into the engine enough to keep it running even when you shut down the throttle.

I ran into this with my M-15 which is amazingly hard to get a consistent dip stick reading on. I ended up overfilled. This lets the crank dip into the oil and churn it, spraying out a lot of oil. When this happened engine kept running even when I yanked the throttle back as hard as I could. No good. Then, on instinct, even though my head knew it was the wrong thing to do, I shifted into neutral, which only led the engine to rev up. I did come to my senses a second after and threw it back into gear before it revved too much.

Then dived below and pulled the vent line from the area of the intake. There were spritzes of engine oil all over the place.

Make sure you don't overfill the crankcase and will probably not happen to you.

What I have done is run the vent hose parallel to the horn on my intake, ending at the lip of the horn. That way the end of the vent line is at ambient pressure with no suction running on it. However, vapors coming out can be sucked back in a U turn to minimze any odor.

If I get a chance I'll take a photo of it.

General advice.

NEVER overfill the crank case.
Place crank case vent outlet near engine intake but NOT connected directly.
Click to expand...

Thank you, that's excellent information! If I'm not mistaken the arrangement I'm using meets the "safe" conditions you describe as it is essentially set up as you describe (hose ending near the air intake) except on my engine the air intake has a filter around it. In other words while there is certainly suction coming from the air intake it seems to me that it would be mostly bringing in air (through the filter) rather than creating meaningful suction on the hose from the crankcase. The crankcase hose is not a direct lead, it goes through a strainer (acts as an oil trap) so there is even further safeguard against excessive oil entering the intake. There is little oil in the "trap" (or the filter) despite having used this setup for about 100 hours so far. Am I making any sense?
 
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