Yamaha '04 90hp 2 stroke oil tank leak from low level indicator cap?

[CaribSurf]

I went through 3 of the engine oil tank level gauge units on my former 2004 HPDI's , over 450 hours of ownership. I found the heat of the engine,plus daytime heat that builds up under the engine cover slowly softens the rubber.Also at +$150.00 a time,its a significant amount of maintenance cost, in such a short amount of hours.

[southpac]

Oil tank sensor leak

Greetings from way down in New Zealand. My Yamaha 90 2 stroke has the same leak just developed after 370 hrs. I'm really grateful for your thread on this fix and wonder how it has lasted? I realise this thread is a bit old now. How does the sensor assembly remove? Just pressed in or threaded? Rotate to remove? I think there has been mention of an alignment lug or some such? Welcome any input and help!

[WhalerGirl]

Same here!

I have the same issue on my 90 2 stroke, but i tried the zip tie and it didnt help, it only leaks when motor is tilted up

Same here- only when the motor is up. This happened to my 1991 90 2 stroke. I can't afford a new or used motor, so I had the stupid expensive cap replaced. I'm thankful for every year I get out of this engine at this point.

At least I can tilt my engine out of the water and not have an oily slick in the front of the bottom cowl.

Good luck!

[NCFD#078]

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Here ya go and it did the job! The other ugly is heating expands the air inside the tank forcing the oil up the gap around the alarm and past the failed seal and then cooling contracts to pull in air for the next round. With the seal secured, the pressure will take path of least resistance and "burp" the rubber tank cap instead.

Good luck and keep us posted.

Question, I'm having the same problem as everyone else on this old thread. Did you wrap the seal and then slide the white tube up to the seal or did you wrap the seal and the white tube together? Also I'm having a hard time getting rubber cap back on the oil reservoir. Any help would be much appreciated.

[hydraman]

Oil tank leak solved

I have a 2004 Yamaha 90 2 stroke with 72hrs on the clock, which developed the same problem that everyone else on here, and many other forums, has had. I have asked two Yamaha dealers locally and they were of little help. The oil leak problem is two fold, which I guess is why others are having trouble solving it.
Firstly, over time the one way diaphragm valve in the centre of the filler cap has become clogged, or as in my case gummed up with oil residue. This valve should let air into the tank as the oil is used up but not let oil out when the motor is tilted up. Failure of this valve will result in either of two things - oil leaking out when the motor is tilted up or pressure building up in the tank to the point where oil is pushed out under the push in low oil level sensor seals. To clean this valve, pry the hard plastic cover out of the centre of the filler cap then carefully remove the valve under it. Wash this in petrol and reassemble, making sure the valve is sitting in position carefully, and all airways are clear.
Secondly, and more importantly, the low oil level sensor (which pushes into the tank) has two raised o ring type ribs on it to seal on the inside of the tank where it pushes in. The height over these ribs was 25.4mm and the bore in the tank was 26.2mm. So effectively they were doing nothing and all the sealing was having to be done by the outer rubber lip which goes over the rim on the tank. I solved this by machining a small o-ring groove between the two raised ribs on the sender to suit a standard 118 o-ring. This will give an outside dimension when fitted of 26.9mm which will give the correct amount of crush when pushed back into the tank. After reinstalling the sensor, I made sure that the outer rubber lip was over the moulded rim on the tank and secured it with a very small electrical zippy tie. I would suggest that any machine shop could supply this o-ring and machine it's groove in the sensor for under $20.00. All the best. Kevin

[Bwerley61]

Tie wire solution

Home depot and Lowes sell 16 gauge tie wire in 300' rolls. It's used for tying rebar in concrete. You'll need about a foot long piece. Use it like a zip tie except when you twist the wire with pliers it'll get much tighter than a zip tie. It has taken my leak from a nasty mess to about 95% stopped. I wrap an absorbent cloth around it to deal with the rest.

[christerd]

I have a cheap possible solution that have been working on my 40 hp. Buy some thin nitril gloves and cut of a finger and put it over the sender tube close to the top. It is easier to get the rubber over the tube without braking the rubber if you first make a ring of the rubber finger and after it is positioned on the tube you can work it out evenly.