175 Vmax HPDI oil in air intake

[msobie64]

So I fished for a few hours this past weekend and the motor smoked a bit. After some investigation it seems the oil reservoir overfill drains into the air intake (pulled it and found a good amount of oil in bottom). I drained the oil reservoir in the motor via the nipple and turned the key to on position. As expected I got the low oil alarm but it slowly filled and turned off at the low mark on the reservoir but continued to fill to the max line then stopped. I suppose with the trailering in the up position it could have leaked on the way to the lake. Is this normal? Should I disconnect this overflow before trailering? Also is it possible if the key is left on it will continue to pump oil in the up position?

[99yam40]

some motors disable the pump when tilted over a certain amount,
I have no idea which ones, so that would be something to check on

[boscoe99]

With one exception the oil pump should never operate with just the key in the on position. In your model the motor has to be running for the automatic oil transfer system to work.

Have you been able to verify that the oil level in the tank got to the point where the tank was completely filled such that oil flowed out of the vent tube and on to the air intake silencer?

In a normal situation oil should never flow out of the vent tube.

[msobie64]

Well thats no good, all I did was turn the key to on position and the alarm sounded until the tank filled. I haven't been able to recreate the oil level going above max but it seems to be possible is sloshed around in the full tilt position however.

[boscoe99]

If the main tank is empty and the remote tank is filled, that is the one exception. Referred to as the initial fill mode. When the motor was new.

[boscoe99]

If the boat was parked down hill on a 45 degree slope and the motor was tilted fully up then maybe some oil could flow to the intake silencer. Was that the situation?

[msobie64]

No definitely not the case. It's trailer stored and is always down unless on the move. The drive was only 30min to the lake and yes over a pretty steep grade but not for long. I did notice today that the oil linkage bar wasn't adjusted properly. The lever wasn't totally against the stop even at idle or just out of gear (now I did quite a bit of idle/low speed motoring around as I normally do when the kids are onboard), not sure if that could have caused it or not. I adjusted it today and plan on cleaning out the silencer and cowl this afternoon of any residual oil. I also have a new oil sensor unit & check valve on order just in case it's starting to go.

[boscoe99]

Three switches in the main oil tank sensor. When the top switch closes it applies a ground to the ECU. Telling the ECU to stop the transfer of oil. A bad switch, or more likely a fault in the ground circuit, could cause a delay in the pump turning off. Or failing to turn off at all.

[msobie64]

In my test the sensor worked fine and cutoff right at max which I’m assuming is normal. I’m going to swap it anyway just in case. I cleaned out silencer with my compressor and noticed the oil overflow port passes air fine but the siphon port that goes to the intake barely passes any air. I’m assuming this is by design?

[msobie64]

I got my order from SIM Yamaha over the weekend and replaced the oil lever sensor/oil filter that runs between the pump and the VST. All tested fine. After some further investigation I'm convinced the excess oil pooling in the silencer was due to two issues. #1 the Siphon port on the bottom of the silencer was obstructed (would not pass any air even when compressor was connected, this has been cleared), #2 the oil pump linkage was not adjusted properly even at idle or just out of gear the lever was not resting on the stop and actually was pretty far off I'd say 1/8th inch so I'm convinced I've been over oiling when at low speeds which would explain the state of my plugs every year. Both of these have since been remedied and i'm hoping to get the boat out this weekend for a hard running session to confirm my findings.