Name this part - my Universal M-25XP

[dustintodd]

It's just embarrassing that after 3 years of ownership I am just noticing this but you know what they say. I always say there are no stupid boat questions, just clueless owners (like me). There is a hose dangling down the right hand side of my motor that is releasing exhaust gases into my engine compartment. The hose is attached here at the top of the motor:
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Then the hose dangles down the side here:
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What is this and why are hot engine exhaust gases and maybe some oil escaping from it? So much to learn, thanks in advance.

 

[treilley]

That is positive crancase ventilation. It is allowing gases to be released from the crankcase usually caused by blow-by of the pistons. Nothing to worry about unless becoming excessive. Then do a cylinder head test to ensure your compression is up to par. If not, this could indicate time to rebuild.

 

[dustintodd]

Ah!

Quick read on the internet tells me the amount of escaping exhaust is sign of the condition of the piston rings. So the compression test will tell the tale of ring condition?

- Dustin

 

[treilley]

Basically, yes.

If you have low compression, piston rings could be one of the factors. Worn valve seats could also cause low compression. However, if piston rings are worn you will have low compression.

 

[Sven]

Isn't the positive crankcase ventilation supposed to be fed into the air intake ?

-Sven

 

[dustintodd]

Smoking gun

I see a regular flow of exhaust gases out of the hose. A healthy engine would show little or none?

 

[treilley]

Isn't the positive crankcase ventilation supposed to be fed into the air intake ?

-Sven

In most engines but not on many diesels used in tractors, etc. Feeding it into the intake manifold is more a function of emissions than crankcase ventilation. These engines are not covered under normal DOT emissions standards.

Dustin, some gases escaping is normal. Only a marine mechanic can tell you if yours is excessive. I have never seen none.

 

[Loren Beach]

By the time the Universal M25xp engine evolved to the current model M23XPB series, that hose changed to a pre-formed version that makes a quick 180 degree loop (at the valve cover exit) and is led back over the fuel injection tubing to discharge against the air filter for the intake.
This sucks those smelly crankcase gases back into the air flow to the intake manifold.
Matter of fact, I recently made this hose change over on our '88 M25XP. Another E owner in my yacht club has previously done this on his M25.

After a good run under power last Saturday to check things out, I can report that the engine compartment seems to have no more obnoxious "oily odor" after opening it up. As advised by our mechanic, we do also run the blower all the time the engine is running, so no change in operating procedure.

So far, so good.

Loren

 

[treilley]

Loren, some photos of your installation would be great. This project is on my to-do list and seeing your solution may move it to the front.

 

[Sven]

In most engines but not on many diesels used in tractors, etc.

I think even our 30+ year old Perkins has the PCV plumbed to the air intake, but I could be mistaken. I sure wouldn't want exhaust fumes blowing into the bilge even if it is just the small amount that might get past the rings :-(


-Sven

 

[dustintodd]

Vaporized oil

I was told that the mechanical motion in the crankcase vaporizes a small amount of oil which then ends up getting discharged out this valve. Is it ok for the oil mixture to enter the air intake?

- Dustin

 

[Emerald]

Feeding crankcase vapors back into the intake is common and OK. Unless your engine has something like really excessive blow-by, and you would have other issues going on, like the massive blue cloud emanating from your exhaust, you shouldn't have an amount of oil to worry about, even after many years of use.

 

[dustintodd]

Picture of the m-25xpb setup?

Anyone have a picture of how it's fed into the air intake filter on the B model?

- Dustin

 

[Loren Beach]

Photos, as requested

I believe that I saw a display engine last year with the hose now plumbed into the intake manifold, but am not completely sure.
My photos show my installation of the newer standard hose and the angled cut-back to match it, crudely, to the shape of the air cleaner and is exactly like the hose on a new M25XPB I saw on display about 5 years ago.

So... I cut off the end of the new hose and seized it in place by tie-wrapping it to the fuel injection piping just like that new engine I once saw.

The front view shows the hose but not a good look at the 180 degree turn it does after being clamped to the down-facing elbow on the valve cover.
Hope this helps a little bit.
(I certainly lack Mainesail's expertise with close-up digital photography!) :nerd:

Note: when you buy this preformed hose from the Universal dealer, it is straight-- with the 180 degree turn molded into one end, kind of like a swimmer's snorkel.

Cheers,
Loren

 

[dustintodd]

Worth a thousand words

Ok now I get. The hose just ends "near" the intake. Totally unrelated: I need the crazy bronze colored engine paint to touch up my motor. But I need something I can paint on not spray. Any pointers?

 

[mherrcat]

I tried something similar on my M-18; terminating the hose next to the intake "snout" (couldn't think of a better term!) on the air filter housing. I noticed, however, that the suction into the air filter housing didn't seem sufficient to catch all the vapor from the PCV hose. I'm thinking of adding a fitting to the filter housing to attach the hose to. (My motorcycle uses a similar setup to vent crankcase vapor into the carburetors via the air filters.) Previously the PCV hose was actually inserted into the filter housing intake; probably not as originally designed.

 

[Maine Sail]

This is how I fixed it..

I found a K&N filter at a motorcycle shop with the same diameter as the intake throat on the M-25. Sorry I can't remember the part number but just measure the intake throat with some calipers and then find a K&N to fit.

The arrow is pointing a 90 degree brass fitting I drilled and inserted into the bottom of the K&N for the PCV valve I made.

Here's a picture of the PCV set up I made. The hose runs from the valve cover to a 3" long X 1" dia brass nipple with barbed female fittings on either end. Inside the brass nipple I rolled up some oil absorbing pad, loosely so as not to restrict flow. The design of this is to absorb any stray oil or oil mist escaping the valve cover so it would not pass to the intake.

I would simply change this piece of rolled up bilge pad at each oil change. By adding this PCV valve I no longer had any oil smell in my engine compartment after running the engine.

The factory set up just vents the crank case into the engine compartment. This equals smell. If you add a K&N make sure you have enough room in the underside of the filter for the 90 degree fitting for the PCV hose. My K&N was off set slightly giving me room to drill through the bottom and insert a fitting on one side.

I purchased all the brass fittings at Home Depot and did the whole project, including filter, for under $50.00.

 

[mherrcat]

Those are the same filters on my bike. Here is a picture of the setup; the hoses on the tops of the filters are from the crankcase. K&N sells the hose barbs and rubber grommets. I have also seen vent collector bottles that make it easy to drain collected oil.

I also found an article on crankcase venitlation here:
http://seagrant.uaf.edu/bookstore/boatkeeper/crankcase-filters.pdf

 

[dustintodd]

Crankcase ventilation filter

I have been looking at ventilation filters online and they offer a port to drain the collected oil back into the engine block.
http://www.maesco.com/products/racor/r_ccv_intro/r_ccv_intro.html
On our Universal where would it make sense to connect this?

 

[treilley]

I believe the M25XP already has a foam filter element in the valve cover to reduce the amount of oil coming out. I would also think if you ran the breather hose vertical out of the valve cover oil would drain back into the engine by gravity.

If you have so much blow-by that it is spitting that much oil, use your money for a rebuild, not an oil collection system.