Bow thruster leakage

hi -

We had similar problem on our 445 with Quick BTR185 thruster - a liter a month maybe, and only when we used the thruster. It turned out that shaft seal was leaked and it looked as if the flange leaked but upon closer investigation it was clearly above the flange - at the shaft. Further we found out that the oil from the submerged part of the gear started leaking (maybe due to some mechanical failure due to some abnormal force on the prop like the rope getting into it or some other thing) and that oil came up in the submerged thruster housing and started eating away rubber shaft seal. So first salt water that seeped inside was a bit oily and dirty and then clear salt water started coming in. Very little of it and only when used. We ended up changing the thruster.

Edited by Konstantin - 03 August 2019 at 11:12

Hi Jon. The seal occurs below the motor shaft and flange. It happens at part #41 on your drawing which is called the drive shaft. It is separate from the motor shaft. The seal is a lip seal part #40. They eventually fail but are readily available and cheap. It needs to be done out of the water. There is another issue though. Once the seal fails, water make its way past the drive shaft and to the motor shaft under the flange. Water can seep out from the flange but can also make its way into the motor which is bad. 

CORRECTION. The oil seal is part #38. Part #40 is the upper bearing. It’s not a bad idea to replace the upper and lower bearings along with the seals, because once the seals fails they are exposed to salt water and will corrode. The entire assembly is available as a part and can be purchased at SVB Germany. Get the part number from Quick Italy, not Quick USA.