Bow Thruster Oiler Questions

I seemed to have noticed more of a "grinding" noise coming from my Bow Thruster in the last year. Rather do not remember it being so annoying since I had bought the boat about 2.5 years ago. I have topped off the reservoir about once a year with the recommended 90 wt gear oil. I have suspected it leaks more than it uses.

There has been a lot of oil seepage from around the bottom of the container and hose end near the clamp for probably many years, and I have cleaned up the hull area there a few times. Finally, I decided to look into it closer and try to fix the leak. The feed hose is rather short, so I have limited options of trimming it back. The plastic/rubber part appears to have become quite stiff over the years.

Examining the reservoir more closely, I noticed that the oil was of a deep "forest green". I seem to remember gear oil as a very dark brown. The bottle of Pennzoil that I have been topping it off with turns out to be yellow upon closer examination, so maybe the green is a combination of the colors. In any case, the green seemed most unusual. Has anyone ever run across Green 90 wt gear oil?

My bigger concern was the accumulation on the bottom of the bottle of some kind of white? powdery substance. I have no idea what this is, but chose to take the bottle and hose out and clean the entire thing with the intent of replacing it with clean lube.
To my great relief, it does appear that oil was flowing freely through the hose at least; cannot say how much was actually getting to the gears. 90 wt oil seems a bit heavy to me for this application considering that it is not a "closed system", like a transmission.

The bottle calls for a Super Heavy Duty Gear oil, whatever that is. Anyone care to make a recommendation as to what I should refill the bottle with? I had just picked up the Pennzoil for "topping off" a couple of years ago until I got around to servicing the oiler.

Thanks folks.

Lucas oil has work well on my bow thruster and a buddy boat both these thruster are 20 years old. Noise drop was considerable!

Thanks funangler,

Never heard of Lucus, but I see it on Amazon, so I can track it down. Appreciate the tip.

BTW, I originally came from your neck-of-the-woods before I escaped the snow a few decades ago. Grew up in Conneaut; father was a Mate on the ore boats fifty years ago.

When my Side power reservoir emptied its contents into the anchor chain locker in heavy seas, I topped it up with EP 80-90 from the local Volvo people. Seems OK so far.

My Sidepower bow thruster had seawater intrusion into the gearleg due to improper installation (whoever installed it did not mount it using two exterior gaskets nor sealant per instructions). This led to corrosion of the shaft, a worn shaft seal, constant loss of oil and lots of noise. Had to buy a new gearleg.

The new ones are sealed and do not require an exterior oil reservoir. The new gearleg also came with Sidepower's new "Q" prop.

Much quieter.

Thanks again funangler,

I took the whole reservoir out, dis-assembled and cleaned it thoroughly. Turned out there was a somewhat "crushed" O-ring in the big nut at the bottom contributing to the leak. I think the stress had also begun to crack the bottom of the canister as well; polycarbonate, I think.

I cleaned it all up and did my best to epoxy the cracks on the bottom - anybody's guess how long that will last. Put in new O-ring and patch to the hose.

Flushed out the hose and Thruster entry with lots of WD-40 before running a bunch of that Pennzoil back through it, followed by the Lucus.

Put it all back together, filled it up and checked for leaks - so far, none.

Exercised the Thruster for short periods during the day and it just got quieter and quieter. Fantastic results!
I think I can rest much better now knowing it is all cleaned out and has new premium gear oil in her. The results speak for themselves. Hopefully the Thruster will still out-live me.