Tohatsu MFS6B Oil Pressure Warning

[rsnyder518]

I launched my boat this weekend and when I fired up the motor the oil pressure light was on. It went off eventually but I have some questions.

1. I test fired the motor at home and the light did not come on.
2. I transported the motor on it's side (tiller down/shift lever up) to the boat and installed it on the mount.
3. The motor sat on the boat for about a week since we were not able to launch due to other issues. I would have assumed this would have allowed the oil to drain back to it's normal "location".

When I launched the motor fired on the second pull and I had turned the choke off when I noticed the light. I immediately shut the motor down and checked the oil level which appeared to be fine. I know to be very careful not to overfill this motor and it is not overfilled.

I fired the motor back up and the light was on. I gave a quick twist of the throttle thinking that quick burst of RPM might help the pump and the light went off and stayed off afterwards. I have not been back to the boat so I don't know if this is going to reoccur.

I read in the owners manual that the light comes on when the motor is first started and stays on for "several" seconds. I have never previously noticed this. Maybe it never did it, maybe I just never saw it. I don't know. But that got me wondering if what I was seeing was just the normal light coming on when it started. How many seconds can this light stay on before I become concerned? I didn't see that information in the manual.

I have the service manual and can go through the diagnostics if this happens again (I'll need an oil pressure guage). But I was just wondering what the collective wisdom here thought? Was I just seeing the normal warning at start up? It seemed like it lasted 10 seconds or so. Thanks in advance!

 

[LudwigO]

Re: Tohatsu MFS6B Oil Pressure Warning

I launched my boat this weekend and when I fired up the motor the oil pressure light was on. It went off eventually but I have some questions.

1. I test fired the motor at home and the light did not come on.
2. I transported the motor on it's side (tiller down/shift lever up) to the boat and installed it on the mount.
3. The motor sat on the boat for about a week since we were not able to launch due to other issues. I would have assumed this would have allowed the oil to drain back to it's normal "location".

When I launched the motor fired on the second pull and I had turned the choke off when I noticed the light. I immediately shut the motor down and checked the oil level which appeared to be fine. I know to be very careful not to overfill this motor and it is not overfilled.

I fired the motor back up and the light was on. I gave a quick twist of the throttle thinking that quick burst of RPM might help the pump and the light went off and stayed off afterwards. I have not been back to the boat so I don't know if this is going to reoccur.

I read in the owners manual that the light comes on when the motor is first started and stays on for "several" seconds. I have never previously noticed this. Maybe it never did it, maybe I just never saw it. I don't know. But that got me wondering if what I was seeing was just the normal light coming on when it started. How many seconds can this light stay on before I become concerned? I didn't see that information in the manual.

I have the service manual and can go through the diagnostics if this happens again (I'll need an oil pressure guage). But I was just wondering what the collective wisdom here thought? Was I just seeing the normal warning at start up? It seemed like it lasted 10 seconds or so. Thanks in advance!

My MFS15C does the same thing every start. I guess its just a way of showing both that the oil pressure may be low when starting, but it also shows that the lamp is working. I read somewhere (not sure where now) that if the lamp doesn't go out in 8-10s there might be a problem with oil pressure.

I always watch the light until it goes out, the same way I always watch the cooling water "pee".

 

[pvanv]

Re: Tohatsu MFS6B Oil Pressure Warning

Yep. The light is on when the pressure is low. It should come on briefly at every start. That time can vary a lot, depending on oil viscosity, temperature, oil level, and how long it has been since the motor was last run. Sometimes enough oil has drained back that it takes a few more seconds to fill the oil galleries.

 

[rsnyder518]

Re: Tohatsu MFS6B Oil Pressure Warning

Thanks guys, sounds like it was probably normal then. It was very hot for the week that the motor sat so maybe the oil was extra thin and in combination with transporting the motor on its side the oil had drained out of the galleries thus taking longer to pressurize as pvanv suggested. I had just never noticed the light being on for any "extended" period before and got concerned.

Hopefully I'll be sailing this weekend so I'll pay extra attention this time to how long the light remains on.