Tohatsu MFS6B - Oil Pressure Light illuminated dimly

[rsnyder518]

I have an MFS6B Sail Pro motor and it's run well all season. Last night we motored over to a restaurant and left after dark. I started the motor and the oil pressure light came on brightly for a few seconds and went off which I believe is normal. However, it didn't really go "off" it remained very faintly illuminated and it slightly flickered in time with engine RPM. It remained the same in and out of gear and at all RPM. It may have been doing this all year but it was so dim that I'd never be able to see it in daylight. Is this normal or is there some other issue? Thanks!

 

[Sea Rider]

If the engine has the correct amouint of oil in the crakcase, not an issue. If so, probably a faulty oil switch/sender or even an oil pump pressure issue ?

Happy Boating

 

[rsnyder518]

I got the motor new in 2010 and it's on a sailboat, so not a ton of hours. Professionally tuned up by our own pvanv at the beginning of the season. I'll check the oil level in case the motor used some, but I'd be very surprised given the small number of hours that I use this motor. Same thing if it's an oil pressure issue. That'd be hugely disappointing on such a relatively new motor with such low hours. Like I said, it's very faintly illuminated. In daylight I'd never ever see it. I only noticed it because it was dark out. When that light is truly "on" it's very bright. and visible in daylight. So some issue with the sender I hope? I was even thinking that maybe it was somehow "normal" but I guess not.

 

[pvanv]

The LED is very sensitive to small leakage currents -- even some water on the wiring can cause a faint glow, even though everything is working as it should. The fact that it comes on brightly at startup and then goes out tells me that you are probably OK. You may never see that faint glow again. In some cases, it's actually ambient light from a dock light or street light (around sunset especially) reflecting through/off the red lens of the LED. We can put a mechanical oil pressure gauge on the motor when you bring it in for off-season service and verify that the pressure is OK.

 

[rsnyder518]

It definitely wasn't a reflection. It was dark that night and at idle I could see the light pulse in time with RPM. Somehow it seems that the ignition is inducing a current in the light.

Hoping to sail this weekend and pull the boat for the season on Monday. I'll take a look for anything obvious like exposed conductors or corrosion. Then as you said Paul, we can check oil pressure during off-season maintenance. But I'm pretty confident that this is an electrical issue and not a mechanical one.

Thanks everyone for the advice.

 

[pvanv]

Yes, the CD powers the LED, so any minor leakage current can cause a dim light. Often, it can't be seen in the shop. In that case we can turn off the lights to see if it's lighting.