smoking crankcase breather....

[degreeoff]

Hello, my lil M25 seems to pur BUT I have noticed smoke coming out of the breather hole. How much is too much and is it a problem? I have no hose attatched to it and was debating running it to the airfilter to suck it back in.

thank you all

Josh

[sailor50]

I would not suggest bringing any breathing hole back in to anything. If you are smoking - I would suggest stopping! Something is not right there!

[degreeoff]

well then what is not right? is it blow by? I mean the engine purrs.

[Faster]

This is in all likelihood blow-by... most Universals have a hose that leads to the air cleaner intake/cannister/filter for pull these fumes back into the engine.

Our son's engine (same one) runs smoothly and reliably as well, but has considerable blowby. Eventually it will have to be dealt with but for now to avoid smelling up the boat he has a hose from the PCV valve to the intake 'snorkel', and has installed a blower on the engine compartment that runs while the engine runs.

[degreeoff]

Thanks, that was what i was looking for. I was thinking a tube to the intake and call it a day. The sad part is this engine only has 417 hours on it! i wonder if it could be because I have not put a good load on it yet? I just bought the boat in Oct and will be floating her in week or so for the first time.

[r.furborough]

Normally the crankcase breather is routed to the air intake so that the crankcases gases are burned in the combustion chamber and not vented to the atmosphere. If blowby is excessive and oil in a heavy vapor is also present, then it is an early sign of piston ring wear and will require attention at some time.

Every engine has a crankcase breather, even todays more modern engines, the gases are normally recycled. Adding the hose to the air intake filter is OK.

[KeelHaulin]

Sounds like the rings did not properly seat in. I would try and run the engine for at least an hour or two with a good load on it; maybe towing warps or against a drouge. You might also want to run an engine break-in oil for the next 100 hours or so to help increase the cylinder wall friction.

[saildog1]

I stuck the breather hose into a plastic coke bottle on my 25XP. It didn't smoke but it did drip oil.

[Capnblu]

The crank case breather goes to the air cleaner, like you said. If it were meant to be shoved into a 2L bottle, that is how the MFG. would have supplied it. But since they did not, stick to connecting it correctly. If you want to know the condition of your "new" motor, do an oil analysis, and a wet and dry compression test, and of course a thorough visual. With this information, you could then diagnose any problems. Without this information, you will simply be , guessing and chasing Murphy.

[olson34]

The stock crankcase breather on the late 80's M25XP was vented straight down and the short hose terminates just behind the motor mount. This lets some smelly crankcase gases out that show up inside the boat even with the exhaust blower running.

The next version of that engine series, the M25XPB, had the hose routed back over the top of the engine, with the end of the hose cut at a slant and pushed up against the air cleaner.
I made that upgrade/change on our engine.

Later they must have routed it directly into intake manifold, perhaps.

L