C-28 check engine oil light on

[boaterjoe]

I have a 2015 c-28 and just completed my 200 hour service. At lower RPMs, under 1000 my check oil light comes on. As I build speed the oil pressure rises and the light goes off, only to come on again when entering the harbor at 5 knots. I checked the oil and it registers near the max line. Any suggestions?
thanks
boaterjoe
Flying Turtle C-28
Bainbridge Island

 

[Rednuke1]

I know this sounds simplistic, but I’ve got to ask the obvious: when you changed the oil, did you also replace the oil filter(s)?

 

[boaterjoe]

Yes, I did change the filters with volvo filters. So I think it is a bad connection at the engine? does anyone else have any ideas?
boaterjoe
Flying Turtle C-28

 

[Brian B]

I had a similar situation with the Yanmar 4BY2 about 2 years ago. After an oil and filter change the oil pressure gauge was erratic. I ended up replacing the oil pressure sensor after testing the resistance of the original sensor.

 

[knotflying]

I am not very familiar with the Volvo. Most oil sensors work using ohm resistance and then the computer interpolates ohms to pressure. The first usual question is what did you do last that may have changed? Did you use the correct oil viscosity and type? If so I would first make sure all connections from the sensor are clean and in good order. I would then put an ohm meter on the sensor terminals and see what reading you are getting at idle and increased RPM. There should be a reference somewhere from Volvo indicating ohms at specific RPM. If that checks out okay there is a communication issue with the computer. If it does not check out okay it could be the sensor or an actual low pressure. You can eliminate that question by installing a temporary mechanical gauge. Or you could just change the sensor and see what happens. I am sure the sensor is not cheap, so pick your poison.

 

[BB marine]

I agree with Mike. If you didn't have the issue before the oil change go through the steps. Correct viscosity oil, correct oil filter, correct oil level. It sounds like you are using Volvo products. I personally would replace the oil filter again, I would confirm proper viscosity, Check the oil level and check the attitude of the boat with a level bow to stern and port and starboard. My oil level on the stick is different on the trailer with the boat level compared to in the water. If all oil change items check off good time to look at electrical issues or mechanical issues.





This is the troubleshoot procedure for oil pressure.



. Too low engine oil level.
• Blocked oil filter.
• Engine oil contaminated or too thin (low viscosity)
• Faulty sensor.
• Faulty pressure reduction valve.
• Blocked oil suction pipe.


1 Check the oil level in the engine. Be sure not to overfill the engine.
2 Check that no oil leakage occurs.
3 Check that the oil filter is not blocked by changing the oil filter. Change the oil.
Be sure not to overfill the engine.
4 Check the oil pressure with a manometer to verify the function of the sensor. Please, refer to “Lubrication system, Workshop manual where to connect the manometer.
5 Replace the pressure reduction valve located after the oil cooler. Please, refer to “Lubrication system, Workshop manual.
6 Check that the oil suction pipe isn’t blocked. Replace the oil pump. Please, refer to “Lubrication system, Workshop manual.




There may be a way of measuring the sensor with resistance, most sensors used Volvo post the resistance values. The oil pressure sensor resistance values are not given. A .5 volt reading is a satisfactory value (static) and max 4.7 volts highest pressure.

This is the test procedure from the manual.

Checking the oil pressure sensor
Tools:
88890074 Multimeter 885675 Break-out cable

1) The measurement can also be performed using brake- out cable 88890122 with measuring box 9998699.


2) Cut the current with the main switch.
a. Connectbreak-outcable 885675 between sensor and EECU.
or
b Disconnect the EECU and connect 88890122. Connect the EECU to 88890122.

3) Use multimeter 88890074 for voltage measurement.


4). Turn main switch on.
Measurement points

Nominal value 2 – 4 (888675)
A93 – A56 (88890122)
U ≈ 0.5 V (ignition on)

 

[boaterjoe]

Thanks to all who responded and had good ideas. After talking to Ronnie at Bellingham Yachts i discovered that the check light was actually the coolant sensor (volvo dashboard light is not that visible) and that the sensor is VERY sensitive to coolant levels. I checked and put in approximately two cups of Volvo mixed coolant and the alarm light is off. Problem solved. Goes to show you have to ask the right question to get the right answer.
boaterjoe

 

[Cutwater28GG]

You should check the hose clamps on the back of the heater by the helm and where they join at the forward end of the engine. just give them a tighten. this is where coolant usually likes to take a walk