Mr1 oil in the intake / filter

[Jgorm]

We know that over filling the oil causes oil to spray out the spark arresters and contaminate the air filter, but where is it coming from?

The center vent on top of the oil cooler goes straight into the valve cover. If the oil reached to top of the oil tank it could flow into the valve cover.

My only theory is that it's filling the heads faster than they can drain. The oil flows past the valve seals into the intake/ throttle body area and sprays out during reverberation. Does this make sense? Is something else going on? I would think the valve seals would prevent this.

I know it's weird filling the oil in these. I've found you need to run it multiple times while you keep checking to get an accurate reading. I did a couple starts, and it was low so I added more until it was at the line. The next day I checked and it was at the top. I pulled out some oil and ran it for a bit on the hose. Then it was way low.

I still don't have a great understanding of the dry sump operation and oil flow paths. Let me know if anyone had information on this.

 

[itsdgm]

I know that your version of the mr-1 is different. Especially with the air intake being up top. But I'm sure the concept is the same with the plumbing set up a bit different. Here's how I believe my 110hp engines can get oil back to the air filter.

It all starts behind the oil cooler, down below the exhaust manifold (where the circle is in the pic). There's a crankcase breather hose down there that goes into a small black box. I believe the box is designed to trap the oil vapors and let the crankcase breathe. It then recirculates any vapors back into the air intake. Through the hose with the arrows. I'm sure your model has a similar breather. So if there's too much oil in the engine, it ends up being forced back into the intake.

 

[Gym]

@Jgorm, when refilling the MR-1 it's important to initially replace ONLY the amount removed from each engine. When this is done you should have some oil indication at the bottom of the dip stick. If not, add a little more until just visible on the stick. You then fine tune the fill after running at cruise speed for several minutes, then at no wake speed for a couple of minutes. Then shut down and bring the level to the full mark. The only time you should see the oil at the full mark is on a completely warmed up motor. This process has worked for me over the last 6 seasons.

 

[Cobra Jet Steering LLC]

Two common issues for the problem are first overfilling the oil either when adding it or changing it, the other is a bad or stuck fuel injector allowing fuel to get in the oil and this excess volume causes the oil level to rise , if it is the injector scenario you will smell a strong odor of GAS in your oil tank .

 

[Jgorm]

@itsdgm makes more sense than my theory. I'll have to look at and see how it's routed on my boat. It's trickier to route vapors in when its individual throttle body. Maybe there is a port on the intake box I haven't noticed.
I did notice that my fx140 ski mr1 has an idle air controller and my boat does not. The boat also doesn't have that black box oil separator. What year is your engine? Is it a 998cc? Is it a 20v?

@Gym that's similar to what I do now, but I do it on a (level) trailer. The first time I didn't realize how much you get to run it to get it up stabilize. It's not like a car where you can get an accurate measurement within a few minutes.

 

[Gym]

@itsdgm makes more sense than my theory. I'll have to look at and see how it's routed on my boat. It's trickier to route vapors in when its individual throttle body. Maybe there is a port on the intake box I haven't noticed.
I did notice that my fx140 ski mr1 has an idle air controller and my boat does not. The boat also doesn't have that black box oil separator. What year is your engine? Is it a 998cc? Is it a 20v?

@Gym that's similar to what I do now, but I do it on a (level) trailer. The first time I didn't realize how much you get to run it to get it up stabilize. It's not like a car where you can get an accurate measurement within a few minutes.

The oil issue has been a real learning curve for all us MR-1 drivers. There have been several instances where dealers have over filled these motors.

 

[Jgorm]

Likely oil inlet on the individual tb mr1s.

 

[Jgorm]

The top of the oil cooler is the vent that goes into the air filler box. Adding a catch can on that line would eliminate oil in the intake.