Hi everybody. I am running twin Arneson 15A1Ls and having carried out lubrication oil sampling, one of the samples indicates 0.4% of water in the oil.

I am not sure if this is water that is coming through the rubber boot as it seems like a very small amount, or if it could be consequence of lying still for more than 5 years.

The other tank has no water at all in it.

Anybody here know if this amount is acceptable or is it imperative that I get the boat out of the water and pull out the shaft?

Many thanks

The rubber boot is just to keep marine growth off the ball and socket most of the time I have seen water in the thrust tube it came in through the prop shaft seals , how were you able to check the oil in the thrust tube with the boat in the water ?

[QUOTE how were you able to check the oil in the thrust tube with the boat in the water ?[/QUOTE]

By taking an oil sample out of each oil tank.

By taking an oil sample out of each oil tank.[/QUOTE]

Sorry about that my arneson set up does not have an external oil tank like yours that allows you to check the oil level while in the boat, but I still think you have a leak in the prop shaft seal or the seal under the nut that holds the ball socket in place I would think any water in the oil is bad and will only get worse

I dont know anything about arnesons but are you saying thats a reservoir tank or a sump tank. Does it just hold extra fluid like a brovo or does it circulate ?

Chris

You can contact Arneson direct for the 100% accurate answer directly through the company website info or private message RIK on here... he is one of the same

The 0.4% water is VERY small amount and can be merely from the sweating of the castings when the temperature of the environment changes.

It's not something to be concerned about at that level.

There's only 5 points whereby oil can enter/leave the drive and the same for the water.

Oil reservoir. Long shot
Input shaft seals
Prop Shaft Seals
Ball Seal/Packing
Drain plugs

The boots are not meant to be water tight, only sunlight tight to keep marine growth off the ball as Green Lighting stated.

Where are you located?

Rik

South of France.
Many thanks for the valuable information.
The boat is a twin MTU 16V2000M91 (2,000HP) powered Mangusta 80,
With this boat I'm always concerned that some small parameter change can degenerate into a bigger problem,
I have to say that I highly appreciate the subtleness of the ASD and how very small trim inputs will greatly affect the speed and efficiency of the ride on such a big boat.
The other challenge is to keep the trim gauge reading accurate.