DF225 Oil in air intake

[linesider04]

I have 2005 DF225. I see lots of oil residue in the air intake collector such that it get all over the throttle bodies and back of the motor. I remove the collector, clean it all up and after some time it accumulates again. Any idea why this is happening.
For the record there is no PCV valve on this motor regardless of whet the diagrams show. I believe that was add to later models.

[artdf175]

Not that familiar with your engine as I have a '06 175
However is there a breather hose off the top of the valve cover?
Should feed into the throttle body
That is how oil vapors from inside the engine get burned off
Inspect the breather hose for the presents of unusual oil
Are you using a good marine grade oil made specifically for outboards?
No overheating issues the would/could cause excessive oil vapors?
Art

[linesider04]

Breather hoses are in good shape and no overheating issues. Thermostats have been replaced and issue persists. I run Mobil 1 which is as good as any oil out there.

[Harper]

Have you done a compression check? A leakdown test? Check for anything that would cause excessive crankcase pressure, such as combustion blow-by. Also make sure the crankcase is not over-filled. And since you say you use Mobil 1, "as good as any oil out there (?)," how long have you used it? Have you owned the motor since new? Did you take it through the break-in period? Did you break it in with the Mobil 1?

[artdf175]

I used to use Mobil 1 until it was explained to me that outboard formulas are designed to work at the lower temps that outboards operate at vs the much higher temps of auto engine do
This is a comment from doing a search

You should be using an FC-W oil for 4-stroke outboards. Modern automotive oils have been reformulated for increased fuel efficiency and catalytic converter protection. They no longer meet outboard engine manufactures specifications regardless of the year that an outboard was manufactured.

Advice for what it worth

[linesider04]

I have performed a compression test and checked out according to suzuki specs. I have not performed a leak down test.
I bought the motor used so I did not break it in. Other than this the motor has been rock solid and worked great 7yrs that I have owned it.

[Harper]

Okay, that helps a little. So I take it this oil in the intake is something new, and not happening for the entire time you've had it. You didn't indicate what you oil level looks like right now. Can you describe how much oil we're talking about? Is there enough to be sucked into the combustion chambers and burn, causing any smoke in the exhaust? Bit of a mystery. Can you tell where the oil comes from? What is the collector that you refer to?

[linesider04]

The oil residue is not anything new. It has been present since I have owned the motor. I believe the proper name for is the silencer and not the air intake. I the oil level is between the high and lo marks on the dipstick so the it is not over filled. The oil I'm seeing is a thin film that is all inside the silencer not such that it is pooling up but leaves a messy oil residue all over the silencer and throttle body. I assume the oil is coming from the breather tubes but the inside of the breather tubes do not seem very oily. Is it possible that oil vapor is passing through the breather tubes and condensing out inside the silencer in the presence of the cooler air?
Looking through the parts diagrams I can not understand is why the DF225 does not have a PCV valve while the DF250 has one. There is a bung on the valve cover for one but it is not drilled out. I wonder if adding a PCV valve will fix my problem and relieve some of the crankcase pressure.

[Harper]

I figured you were referring to the silencer. Well, my best guess would be that you have a problem with oil control past the piston rings. There are usually three piston rings (I'm guessing our motors have three also). Two of the rings are compression rings and one is for oil control. The oil control ring is the three piece one (two thin outer rings with a wavy ring sandwiched between). So what you have is probably a bit higher sump pressure than normal caused by compressive gasses blowing by the rings. The higher sump pressures push more oil vapors and tiny droplets out the breather hose than would normally take place. Either the beak-in period was not adhered to as well as it could have been, or the initial oil changes were not performed as diligently as should be. This was the reason that I initially asked if you'd had the engine since new. You have no idea how well the break-in was handled, and as frustrating as it might be, there's probably not much that you can do at this point other than to accept the fact that it will continue, or to do a ring job on the motor. The best thing is that the condition should not get any worse than it is at this point.

[linesider04]

Harper, Thank you so much for your time and evaluation. Do you have any idea why the 225 do not have a PCV valve? seem like this could alleviate some of the problems.

[Harper]

To my knowledge, none of our outboards have PCV valves. And to be honest, I don't think a properly operating outboard engine should need one. If any of the newer models have a PCV or CCV systems, it's probably to quiet the dogs at the EPA.