Topic: oil pressure light came on while idle(cb350f)

[edmer79]

when the engine idle ,the oil pressure light came on.but went off when bike is moving.what is the likely cause?also is it normal to have white smoke coming out from the engine breather tube?

[Geeto67]

Sounds like you are low on oil, how much do you have in the bike? White smoke out the breather sounds like you are burning something, steam perhaps? maybe oil (if it is blueish and not pure white)?

Change and check your oil and see if you have enough.

[edmer79]

oil level is good.i check it constantly.it consume engine oil slightly but does not require engine oil top off.could it the piston rings?regarding the oil pressure could it be the oilm pump?the pressure switch was change 6 months ago but problem still persist.

[Bodi]

Piston rings will not cause an oil pressure drop.
Making some assumptions either the oil is too thin, the pressure sensor is bad, the oil pump is bad, or there's wear in pressure fed parts of the motor; primarily the crank main bearings. Possibly the oil pickup screen is blocked?
The pressurized oil goes directly to the main bearings and the top end through flow control orifices. The transmission is fed by a second oil pump so that isn't your problem.
Also, where did you get the replacement sensor? The Honda OEM one trips at very low pressure (5-10 psi I think) and automotive ones although they fit fine are generally 20 to 30psi and the Honda system just will not normally give that much on a hot engine at idle.

[TwoTired]

Oil quantity is one thing, oil quality is another.  Worn out or damaged oil loses it's ability the behave as thicker oil when hot.  Also, the transmission gears chop up the long chain molecules in oil formulated for modern Auto engines.  These molecules normally allow the oil to have higher film strength, behaving like higher viscocity oil.

If you are not using an oil formulated for motorcycle use of the correct viscosity, change it to one that is and see if your oil light issue persists.

If it does, then you have and indicator malfunction or a serious oil pressure issue to be sorted.

Cheers,

[amattel]

I went through 2 bone yard oil pressure sensors before I finally spent the $30 for a new one from honda.   MY last one would light up at 20-30psi...  I only know that because I bought a screw in pressure guage that attaches in front of my right foot on the engine...  My  cb750k2 idles at around 25psi when hot...  70+ when cold.  Not sure how accurate it really is but at least I know there is a good amount of pressure.

Adam

[HondaMan]

Honda's spec on oil pressure switches is: OFF at 10-12 PSI on the way up, ON at 6 PSI on the way down.
The CB350F almost required 20w50 oil after 10k miles or so. It revved so willingly that the valve guides took a beating, causing blowby into the crankcase, then smoke out the breather tube.

If you're using Valvoline or Havoline oil in the 350-4, stop it. Try Castrol or Torco, 20-40 or 20-50 weight.

The guides aren't hard to replace....

[Lumbee]

edmer...what is u'r idle set to?  My 750 F2 will trip the oil press. light if I let it idle below 1K RPM.  If u have an unuaually low idle and thats when the light is coming on, I don't see this as a big deal.  It seems logical that when a bike idles low the oil pump is also going to slow thus decreasing pressure.  You wouldn't want the bike to sit with the light on for more than 30 sec or so, but if its just for a few seconds when u'r idling, I don't know that its that big of a deal...

...look at it this way...it lets you know u'r oil press. light is working... 

[MetalHead550]

http://www.sohc4.us/forums/index.php?topic=5325.0 

plus see the link within the link.  We've beat this one to death in the past.