1992 100 hp Johnson oil alarm

G-Daddy

Petty Officer 2nd Class
Joined
May 3, 2002
Messages
197
Taking the boat to camp this weekend, so I fired her up last evening. I had just replaced thermostats - I do this every season because I always get overheat alarm if I don't. This time I got the woo-woo-woo oil alarm. The motor is a 1992 Johnson 100 HP commercial outboard. It's a V-4 with the big gearcase. Never had an oil problem with it, so I filled the oil tank and premixed until I can see if the pump is pumping oil. If not I guess I will unhook the oil tank and premix. Is that the best option at this time for a 20 year old outboard?
 

G-Daddy

Petty Officer 2nd Class
Joined
May 3, 2002
Messages
197
Re: 1992 100 hp Johnson oil alarm

Here's something new I discovered over the weekend. After sitting for a while after running the motor, if saw some oil dripping out of the lower cowl down the outside of the leg. I'm thinking maybe the oil alarm is that the oil pump is pumping, but the oil is leaking out before being metered into the fuel? Is that possible?
 

rothfm

Ensign
Joined
Sep 26, 2006
Messages
913
Re: 1992 100 hp Johnson oil alarm

That oil down the outside of the exhaust housing is most likely exhaust (unburnt gas/oil mix) leaking from your powerhead gasket and making dark brown/black streaks at the underside of the powerhead down the motor leg. Post up a pic and we can verify. If this is the case at some point you will need a PH gasket, unless its severe, it should be able to hold a bit. More of a ugly visual.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1992 100 hp Johnson oil alarm

I'd check the color of the oil. If it's clearish, it is likely fresh 2 stroke oil. You can do some checking on your own-that engine has a white/clear sight glass in the oil line just before the pump. When you first prime the oil line, it gets bled till the sight glass fills with the dark colored oil, then the hose gets connected to the pump. Once done, normally the sight glass will always show filled with the dark color of oil. Even after it sits all winter..Next time you go to run it, see if the sight glass is still filled with oil, or if some is leaking and the sight glass is lighter in color. If it leaks out slowly, that could be the reason for an oil warning.
 

G-Daddy

Petty Officer 2nd Class
Joined
May 3, 2002
Messages
197
Re: 1992 100 hp Johnson oil alarm

I will be visiting the boat again Friday and will check. Since everything below the cowling is black it is hard t check color of anything dripping down the sides. I will look for a sight-glass, although I do not recall seeing one. I will look more closely at the oil line as it gets closer to the pump.
 
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