oil pressure sensor

[yvescheung]

hi all, anyone knows where is oil pressure sensor located on a nc31?

having oil light stays on all the time (oil level is ok) so i like to check if it is a faulty sensor or i really have low oil pressure.

the light is on when ignition is on, it's off when i press the starter and it's on again when the bike started.

welcome any ideas/ thanks in advance.

[tomigun]

Αt the left side of the photo you can see the upper body of the engine.I mention the oil pressure sensor as number 2.It is locate right under the carburators.

[yvescheung]

thanks for the handy picture!! it is very helpful. will be looking at my bike tonight.

To be specific - is it something like below?




(pictures from internet...not my bike)

Thank you again!

[bludclot]

I hope it's your sensor and not a worn pump....

[tomigun]

Yes,you must remove this rubber-plastic protective cap.You will find,if i remember well a 6mm bolt and you must unscrew it to remove the sensor wire.To unscrew the sensor you will need 24mm socket key.

[yvescheung]

Can't remove the plastic cap last night, it is too tight. maybe i need some tools to do it, i will try it again tonight.

Have you guys heard faulty oil pump / main bearing clearance problem on cb400sf? Nothing mentioned on the internet about this.

I rode my bike to two mechanics nearby. One said if you have enough oil you can ignore it. Another said it could be bad oil pump but he is not sure.

I half suspect there is oil pressure because if there is really low pressure the engine could have be dead when i'd ridden to the mechanics. And I've been checking oil level - when the bike runs for a while, oil level is lower so the pump is working? Am I correct?

Cheers

[billgrundies]

hi, on my 400sf the cap over the pressure switch is made of rubber and just pulls off. I've only had a worn oil pump on a high mileage machine. your right about the oil level it will show low after a ride due to it being pumped and being picked up by moving parts. the switch is easy to see but awkward to get at. things to check before removal. take off left side panel and you will find a clear plastic bell shaped connector cover, there is a 2pin black connector the dark blue/red wire is the pressure switch, the pale blue/red wire is the neutral switch. check this is clean and a good fit. on the switch itself pull off the cover check the terminal on top is clean, tight and no corrosion. if you have to remove the switch to replace put a dash of sealer on its thread on fitting. don't over tighten the terminal on top. hope this is of some help.

[yvescheung]

Thanks for the reply.

I finally took the sensor off.

The connection is clean because light is off when I remove the wire from the sensor.

I also tried to test the sensor. Applying air pressure to the sensor the light goes off. So it seems working.

I am abit lost because I started the engine without the sensor, the oil comes out (a lot) from the hole where the sensor supposed to sit in. So I should have pressure (maybe not enough??)

I will go buy a manual pressure gauge to see. I will update. Any advice? Your help is appreciated.

[yvescheung]

Hi Bill, the oil level is right on the "max" line of dipstick when it's cold, it's on "low" when I check the oil level right after I run the bike for a while. After few minutes oil flows back to the pan and again it's on max. Seems this is evidence of that the pump is working and engine has enough oil pressure??

[billgrundies]

hi, good idea to check with gauge [warm engine approx 5bar 7000 revs] in the past I've had my xs11 oil light come on when damp, riding in the rain and after a wash. sorted by a shot of wd40. also my old cb550 light came on and proved to be a blocked strainer in the oil sump. if pressure is ok it will be your switch. if not it will be sump off, check sump and strainer for dirt ,check pressure relief valve, condition of oil etc. is it the correct oil and is it good. is the light on from the moment you turn the ignition on and always stays on?. sump gasket will be required. cheers.