Re: Bowthruster Gear Oil

James Alton


   Ahh, so it has finally cooled off in Greece. But what a nice October we had this year eh?  As you have already suspected I am sure that the difference in the flow of the oil is just the viscosity has increase from the temperature.  This is the same reason that changing engine oil with the engine warm, much easier.  In the future if you have the same problem,  just put some gentle heat on the unit such as a 100 watt clamp light or a small thermostatically controlled heater  (in a pinch a hair dryer, but keep an eye on these things, not rated for continuous use) .  No need to get anything really hot, just bring the oil up to 100F or so and it will be much thinner and should flow.  It might take hours of gentle heating to accomplish this, especially if the 54’s have fibreglass cases on the lower units of the bow thruster which does not conduct heat very well.  Hope you also had a good season in Greece this year.

SV Sueno
Preveza,  Greece
Also now high and dry..

On Nov 10, 2019, at 9:15 AM, ngtnewington Newington via Groups.Io <ngtnewington@...> wrote:

I recently hauled out and decided to drain the gear oil from the Bowthruster, the oil was good and not cloudy but after two years needed changing.

Then after replacing the oil drain screw filled up the oil reservoir with 90 weight gear oil. The problem is that the gear oil will not flow. There is obviously some kind of air lock. I managed to get about 250ml in by Blowing into the reservoir, i.e. pressurising it. 

I have now left the boat for the winter and maybe the oil will work its way down by gravity. 

I looked for a bleed screw to let the air out but found nothing. 

Does anyone know if there is a air vent bleed screw? Or is there some trick?


AML 54-019 ashore at the Bazimakoplou boat yard Kilada Greece

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