Yamaha Outboard Oil Tank Sensor Leak

Its leaking oil at the reservoir tank ware i think its the low warning oil sensor.

Yamaha outboard oil tank sensor leak.

Piston picture at end. I put thread tape around the two small raised ridges about 3 wraps that are down the tube a little and around the tank lip where the cap snaps over. Eventually the main oil tank overfills and spews excess oil out a vent tube into the air silencer box. I decided to also replace the drain line that comes from the bottom of the oil tank and re enters at the top of the tank.

Yamaha could do a better job of engineering this bit. I don t know whether it is engine oil lower unit oil or something else. Given the head of oil above the part of the tank the sensor sits on it is no wonder this can leak. Troubleshooting the alarm system includes making sure the horn associated with the alarm works making sure the warning light comes on and the horn sounds when the oil level drops below acceptable levels and ensuring the warning sounds if the engine overheats.

The yamaha outboard alarm system can fail just like any other system on your outboard. So my thought is forget tie wraps and replacement of oil sending units i want to fix this thing permanent with an external oil tank like on the bigger outboards. A plastic tie wrap snugged around the rubber lip usually cures the leak. While the outboard is tilted a leaking rubber cap on the main tank can result from improper assembly or from twisting out of place.

Oil sending unit leak i just found this same leak from the oil sending unit on my 06 90hp after taking the boat out of winter storage. I am the second owner of this matching 2007 19ft. I have a 2004 90 hp yamaha ob. Noticed the last few times out that i have an oil leak coming from this area of the outboard see pic.

I cleaned up the rough edges on the oil reservoir neck top and perhaps this may reduce the oil leaking from the low oil sensor cap. Can answered by a verified marine mechanic.