Volvo QL BP800 Bow Thruster Help

[JoeBeneteauOceanis]

If anyone else is having a leak on the gear housing from oil lip seal this might help. My end cap flanges were badly damaged by electrolysis. So I had them machined off and new bronze plates bolted back on with a gasket. It's all together and has been pressure tested and is oil tight. It was £150 and I didn't have to remove the leg just the end caps. A lot cheaper and a lot easier than a whole new bow thruster.
Hope it's useful.

 

[shortjohnsilver]

If anyone else is having a leak on the gear housing from oil lip seal this might help. My end cap flanges were badly damaged by electrolysis. So I had them machined off and new bronze plates bolted back on with a gasket. It's all together and has been pressure tested and is oil tight. It was £150 and I didn't have to remove the leg just the end caps. A lot cheaper and a lot easier than a whole new bow thruster.
Hope it's useful.

Great job.
I imagine electrolysis is why I cannot remove one of the end plates, it’s just completely seized on. Also, I suspect it’s a shaft bearing/seal that’s failed rather than the plate lip seal and the plate has to come off to get at that.

 

[JoeBeneteauOceanis]

Great job.
I imagine electrolysis is why I cannot remove one of the end plates, it’s just completely seized on. Also, I suspect it’s a shaft bearing/seal that’s failed rather than the plate lip seal and the plate has to come off to get at that.

The end cap was very difficult to get off. What I did to get it off is was use a hammer and a long screwdriver to rotate it slightly just so the bolt holes are no longer in line. Then I gave it a tap on each of those bolt holes alternatively from the other side to push it out. Once it gets started it should move. I'd also suggest using some heat on it to see if that helps if you're really struggling.

 

[VandKoala]

I have replaced mine with a new Sidepower thruster.
If someone needs a well working motor, new relay block or inner parts of the gearbox (the gearbox housing is corroded) send me a PM. It is in Denmark

 

[ck36]

Thanks for posting your experience with this thruster, it's been very helpful....mostly in dissuading me from attempting to remedy my own oil leak on a BP1200. A question I have is what good is that little head tank in the compartment below the waterline? If there's any seal leakage this allows water into the gearbox instead of oil out. I recognize that oil shouldn't be allowed into the water, but at least this could be located to provide a better head to balance with the external pressure. All ships I ever worked on had their thruster hydraulic tanks well above the water line.

 

[Plum]

Thanks for posting your experience with this thruster, it's been very helpful....mostly in dissuading me from attempting to remedy my own oil leak on a BP1200. A question I have is what good is that little head tank in the compartment below the waterline? If there's any seal leakage this allows water into the gearbox instead of oil out. I recognize that oil shouldn't be allowed into the water, but at least this could be located to provide a better head to balance with the external pressure. All ships I ever worked on had their thruster hydraulic tanks well above the water line.

I agree that that tank, being below the water level can have no function in maintaining a seal against water ingress. The shaft seals are normally two seals, back to back, one keeping the water out and the other keeping the oil in, but still, no obvious benefit from a header tank of oil. Most boat thrusters do not have such header tanks, I have only seen them on the larger QL BP thrusters (which are no longer made). We are talking here about electric thrusters, the function of a header tank in a hydraulic thruster is very different.

 

[shortjohnsilver]

I agree that that tank, being below the water level can have no function in maintaining a seal against water ingress. The shaft seals are normally two seals, back to back, one keeping the water out and the other keeping the oil in, but still, no obvious benefit from a header tank of oil. Most boat thrusters do not have such header tanks, I have only seen them on the larger QL BP thrusters (which are no longer made). We are talking here about electric thrusters, the function of a header tank in a hydraulic thruster is very different.

The small header tank to my BP800 is mounted above the water line, but only five or six inches or so. Since discovering the leak I have. Loosely monitored the header tank level and can say that there has been no loss of oil.

When ashore having removed the props I found that the oil seeped very slowly along the shaft. This oil was good and showed no sign of contamination by sea water.
However, the flange is totally corroded onto the gear housing facia flange and impossible to get off without likely causing serious damage.
So, I’ve re assembled everything topped the oil and relaunched.
Im very hopeful that the inward pressure of sea water has equalled the oil pressure leaking out along the shaft and as there has been no change (drop) in the level as the header tank, I believe this is the case.
Obviously this is the situation when the boat is sitting static in still water. And the bow thruster is not being run.
Anyway just thought I’d share this.