Low Oil Pressure

[JDFester]

A couple of weeks ago while pulling a couple of kids on the tube, I got a low oil pressure alarm and speed limiter kicked in. Stopped and checked the oil; it was low. (My fault, I had gotten complacent and hadn't checked it as often as I should...). Added oil to middle of range on dipstick, started and tried again. Same thing after running about a minute at speed with the tube. Pulled in the tube, rechecked oil (no change, still middle of crosshatch on dipstick). Close to ramp, so rode back at low speed and called it a day.

We had not really wintered this year, so I had not done my usual annual oil change, so I did that yesterday morning. Got oil as close as I could on the trailer, but then ran, stopped and let it sit a couple min in water, and rechecked; added oil up to center of crosshatch region, started, and tried to take off. Almost immediate low oil pressure alarm. Check oil again, where it should be. Start again, and try accelerating more slowly. (i.e. ~1000 RPM steps, and run at that speed a min or so then bump up another 1000. This seemed to work things out, as I was up and running full speed like always, able to start, stop, everything like normal. Run up and down the lake for an hour, then head over to a park and dock for a couple hours. When leaving the park, we idle out of the long no wake zone, then try to accelerate, and almost immediate Low Oil Pressure alarm. Start trying the slow increases again, and notice that when I would bump up, it would drop a couple hundred RPM (i.e. I go to 4K, and after a couple of seconds, it drops to 3800 and stays there). Get to 5K, low oil pressure alarm. Did this twice, then idled the rest of the way back to ramp and pulled boat.

Can anyone give me other ideas of what I should check next? Thank you!

 

[Cobra Jet Steering LLC]

Just guessing but you may have a bad sensor or a bad wire connection or a bad filter but doubtful on the filter. When I change my oil on my 1800 engines I have a way to get 4 quarts out and I use a bigger oil filter Fram TG-3600 so it holds 1/2 quart , when I measure it I am at 4.5 quarts of oil , I am also using synthetic oil so I only do changes every 100 hours and it looks like it did when it was new.
Try cleaning the wire connections and the engine ground wire where it bolts to the block, sounds more like a malfunction of the sensor than low oil .

 

[JDFester]

Thank you! I will try to hunt for a electrical fault, and wondered if it could be a sensor, but since the issue seems to be tied to engine speed wonder if there are small passages that might get clogged, and if so, if there is a way to clean them.

When I change my oil on my 1800 engines I have a way to get 4 quarts out

I would love to know more about this method! When checking the oil yesterday, the oil did seem to be darker than I recall from previous oil changes, making me wonder if the old oil had gotten burned/degraded from getting too low, or if there may be some some sludge buildup, etc. Seems like a flexible tray that would funnel through a drain plug hole, allowing an actual drain, should be a thing!

 

[Cobra Jet Steering LLC]

Thank you! I will try to hunt for a electrical fault, and wondered if it could be a sensor, but since the issue seems to be tied to engine speed wonder if there are small passages that might get clogged, and if so, if there is a way to clean them.


I would love to know more about this method! When checking the oil yesterday, the oil did seem to be darker than I recall from previous oil changes, making me wonder if the old oil had gotten burned/degraded from getting too low, or if there may be some some sludge buildup, etc. Seems like a flexible tray that would funnel through a drain plug hole, allowing an actual drain, should be a thing!

Being an intermittent issue and no obvious cause to confirm the warning is accurate I suspect it is a sensor or a bad connection or a dirty fuse connection I would clean every wire connection And spray them with silicon spray Especially if you hose down your engine bay I was told to do that many years ago and I had lots of electrical issues so I decided to spray down the entire engine and all the wiring connections with white lithium grease and I put dielectric grease on the spark plug boots plus I add never seize to the plugs and gear lube to the intermediate bearing housing all before it hits the water for the very first time I am now also using synthetic oil and the oil filters I motioned as these are larger and very strong with walls most filters are thin walled I have seen several thin walled filters rust and leak at the crimp . Since doing these things I have had no issues so far , Also I am only in salt water and over 100 hours per year use. I keep all my new ideas close to my chest so I can not share the oil trick just like them intake grate trick.

 

[JDFester]

Being an intermittent issue and no obvious cause to confirm the warning is accurate I suspect it is a sensor or a bad connection or a dirty fuse connection I would clean every wire connection And spray them with silicon spray Especially if you hose down your engine bay I was told to do that many years ago and I had lots of electrical issues so I decided to spray down the entire engine and all the wiring connections with white lithium grease and I put dielectric grease on the spark plug boots plus I add never seize to the plugs and gear lube to the intermediate bearing housing all before it hits the water for the very first time I am now also using synthetic oil and the oil filters I motioned as these are larger and very strong with walls most filters are thin walled I have seen several thin walled filters rust and leak at the crimp . Since doing these things I have had no issues so far , Also I am only in salt water and over 100 hours per year use. I keep all my new ideas close to my chest so I can not share the oil trick just like them intake grate trick.

Good call on the sensor; replacing it appears to have been the cure. Thank you!

 

[JDFester]

Good call on the sensor; replacing it appears to have been the cure. Thank you!

Well, seems I posted a little too soon. Boat ran great for about 2.5 hours, now back to low oil pressure alarms if I cross 4000 rpm, limping back to ramp…

 

[Cobra Jet Steering LLC]

Ok look at the oil level on the water or with the hull flat, I put a small lever on top of the engine if the oil reads low you have a leak. Remember the limp mode is never a safe mode running slow with no oil will still damage or destroy it. Be sure the oil filter is not leaking Had that happen to me years ago. Glad I found the issue and I did not drive back , I got towed in. I believe that one was a 2013 NA 1800 engine like yours.

 

[JDFester]

Ok look at the oil level on the water or with the hull flat, I put a small lever on top of the engine if the oil reads low you have a leak. Remember the limp mode is never a safe mode running slow with no oil will still damage or destroy it. Be sure the oil filter is not leaking Had that happen to me years ago. Glad I found the issue and I did not drive back , I got towed in. I believe that one was a 2013 NA 1800 engine like yours.

No leaks, nothing abnormal sound or smell-wise. Oil level at top of cross-hatch with boat in water.

Looking at the diagrams, it looks like there is a connector somewhere in the line that comes from the oil pressure switch; I was not able to find it when swapping it out, as it must be wrapped up in a loom/harness somewhere. Guess I will look more for that, and possibly see if I can find an actual oil pressure gauge that I can hook up where that switch screws in to watch…

Still somewhat suspect there may be some sludge or something in the oil pan, are there any additives that could help flush that out if I were to do another oil change?

 

[Cobra Jet Steering LLC]

Why don't you find the ground wires , disconnect the ends clean them and re tighten them in place and spray the electrical connectors with silicon spray to keep them from shorting out if they get wet

 

[Cobra Jet Steering LLC]

2013 Yamaha AR190 (RX1800BMB) OEM Parts, Babbitts Yamaha Parts House look in here for a list for the part you are trying to locate

 

[2kwik4u]

, are there any additives that could help flush that out if I were to do another oil change?

If you do find some low oil pressure and suspect sludge clogging the passage ways. The Audi guys have been finding good success with BG Engine Flush procedures to clear carbon deposits on the oil control rings in the 3.0T. I would suspect a treatment or two with that system would be a relatively low risk, low cost test to see if you could clear any blockages just from running the engine.

If you already have low oil pressure, there isn't much chance of hurting the engine any further.