Oil Light On At Higher RPM

Hello,
I have a 2010 BF30 Honda Outboard. Great motor until now. At low RPMs it runs great. If I increase the RPM's it runs for about 2 to 3 minutes and then the oil light comes on with alarm and it lowers the RPM's to what I am assuming is a safe RPM. Spoke to a couple mechanics and they all agree that it probably is not the oil sender. I am thinking it could be. Any thoughts would be appreciated.

A little confusing, the oil light should be on all the time when the engine is running, you sure it's not an overheat issue?

The red light for oil only comes on when the alarm sounds. The temp light is on and green. When I check the water coming out it is cool so I am thinking not a heat problem but I am no expert for sure. I had a mechanic suggest I take out the oil sending unit and clean it, have you heard of cleaning an electrical sensor? Thank you

Oil sensors are routinely cleaned to remove sludge or debris that may be keeping them from working properly. The one wire sensors are electrical pressure switches but do have an internal mechanical mechanism that the pressurized oil pushes against. The very small orifice where the oil enters the sensor can get plugged. Although, I doubt that is what is happening with yours since it seems to work at lower rpm when oil pressure would be at it's lowest value.

If you are running the oil at too high a level, it can be aerated (whipped into a frothy foam). This can starve the pump and cause low pressure at high rpm. Make sure your oil level is below the "FULL" mark on the dipstick.

If you think your engine is "making oil" then there may be oil dilution from poor combustion causing gasoline contamination. This is usually caused by defective thermostat(s) keeping the engine from reaching normal operating temperature.

You may want to check the thrust of the crankshaft. That is the amount of linear travel that the crankshaft has. If it is excessive, it might cause the pressure to fall off. Some Honda engines have had issues with worn crankshaft thrust bearings but I can't say if the 30hp is in that group.

Just a couple of ideas.....I could be way off because many times a condition like you describe can be attributed to an electrical issue. But it is always prudent to determine if the pressure is actually getting low before assuming that it isn't. Installing an accurate mechanical gauge and duplicating the operating conditions is really the only way to know for sure.

Good luck.

Your engine is overheating, red light is overheat, green light off is oil pressure failure. Service your impeller and thermostat

Download an owners manual if you are not familiar with the warning system of your engine, you will find it most informative.

Thanks for the info. However, there is a heat light and a oil pressure light. The temperature light is working as it should and is green. The oil warning light does not light up at all unless the alarm sounds, then it lights up red. While the engine is running I check the water flow and it is cool to the touch, not hot at all. My understanding is if it is running hot the water would feel warm to the touch. I removed the oil sensor and tried cleaning it out but still ended up with the same results. I appreciate all the info.

Mate,read what I have said, ALL hondas have a green light for oil pressure, when the engine starts it should come on and stay on indicating oil pressure is good. If the red light comes on at any point it is indicating an overheat.A cold tell tale is normal even when engine overheats because it is merely an indicator to say the pump is pumping water and is taken off a passage before entering the block, so always cold.Believe me, your engine is overheating for some reason,I would start by servicing the water pump and changing the impeller

I agree that a cool tell tale doesn't rule out overheating. The water you are touching hasn't entered the engine. It is a bypass or branch of the main stream BEFORE it enters the engine block so it doesn't pick up much, if any of the heat of combustion.

Sorry I missed the obvious clue about the red light. Ian is correct although I would still be concerned about the green oil lamp not coming on as it should too.

Could it be wired up incorrectly? Check to make sure the right color wire is going to the right indicator light. I don't have the color codes for that engine. But many times they are published in the back of the owner's manual.

I am reaching out to you again. As you told me it is a heat issue and not oil issue. So.... changed the thermostat and the complete impeller kit, gaskets, housing etc. Still getting the red "hot" light. The water flow is warm to the touch as you said it should be. Not hot at all but warm. Ran the boat with out the thermostat and no alarm, put the thermo back in and the alarm got triggered. Disconnected the heat sensor and no alarm. while running I reconnected the heat sensor and the alarm sounded almost immediately. Could it be as simple as a bad heat sensor? I did test it with a amp gauge and it seems to be acting as it should. Your thoughts would be appreciated.

Is this motor used primarily in saltwater? Have the internal anodes ever been replaced ? If yes and no respectively, you need to remove the water jacket cover on the port side of the block, replace the anode and there is a very strong possibility that the bottom is clogged with sand and or salt thereby restricting the water flow out of the block. You should also remove the intake manifold too to replace the internal anode.