idlerboat 116 Posted September 29, 2011 Share Posted September 29, 2011 This is something that i just posted on www.metalboatbuilding.org such a simple thing with dire consequenses ... thought it was worth sharing. Drip...drip...drippeople who have read my posts for awhile know that all the gear on my boat systems is new. That also includes the gearbox. It was a difficult decision at the time because my build was a shoe string budget. So I used a super market bollard for my wheel and so many other "cheats".....in fact the boat is full of them . The engine train, the steering...the best that I could...all brand new. Engineered to the highest tolerances, the most important thing being reliability. Let me remind all that that the gearbox is something that is completely neglected. It is a bit of kit that is installed and for forgotten. Let me remind you that if it fails, the results are the same as any other fail of the long line of engine/transmission . So now it is obvious that something happened..... It is so simple and dangerous. A tiny drip of gear box fluid. The drip ran under the gear box and then dropped onto the keelson steel. Nothing obvious, as the gearbox only holds 500ml of ATF all up. It dripped into my "dry" bilge. Hands up who checks their "dry" bilge after it has been dry for 18 months ? Needless to say I didnt. Pure luck had it, that I stored my fuel tank dip stick in the bilge. (yep dip stick...I said it was a budget operation). I decided to check my rear tank for no reason other than it is habbit from the "big voyage"...and there it was. The end of the dip stick had RED....now steering is green and diesel is a soft yellow. There was no question that it was gearbox fluid. On checking, the month sitting in the marina had drained ALL the fluid into the bilge. I think luck is on my side !! TECH STUFF. My gear box is a very well known mechanical gearbox. It is well rated to the engine HP. This type of gearbox uses a clutch pack of multiple discs and detent balls to provide the transition from stop to go. They have a very robust gear train. If there is one "Achilles heel" it is that they rely on a brass thrust washer to take the lateral force of the prop. Up to a point the gear train could be expected to take a reduction in fluid, but the thrust washers need all the help that they can get. This is indeed a fact for me now because I have met many people who have had failures in this part of the box. (My rebuild manual came from someone who had gone through just this) (( you do collect rebuild manuals for your gear ?..If you are a technical person..now is the time to start reading....if something goes wrong...you may find it harder to get good information than spare parts !! Collect them and add them to your ships technical folder.....you do have a technical folder in paper ...dont you ?)) SOLUTION ? The original alluminium drain hole washer for some reason that I still dont understand simply wont seal, It has been torqued to factory specs and I wont go more due to the possibility of stripping the gearbox case threads. That is a complete nightmare. The machined face looks fine. I swapped the identical filler washer, but to no success. The next thing I tried was a very high tech O ring. It worked fine.....for a few hours and then split. I could not have tightened it less and been confident that it would have not undone under normal vibration. So *I had a choice of three left. A crush brass type..dissimilar metals: a larger aluminum one ...maybee: a high tech plastic one. my present choice... At this stage there is no leak. FINAL... I now am worried about something that I wasnt. Such a simple thing, but to lose a gear box in the middle of nowhere is a big problem. Check your fluids often...it took 18 months for my problem to occur.... glad I wasnt 500 nautical miles from home... cheers Martin idlerboat Founder Link to post Share on other sites
wheels 543 Posted September 29, 2011 Share Posted September 29, 2011 IB, if you were going to have a problem with the thrust washers, you would know already. Once you have some of that slippery stuff back in there, they will be OK. You must have had a good lub in there and one of the reasons it is worth using a good lub and one of the reasons why I use Amsoil as the Lube ion mine. If the level drops or water gets in, hopefully the box will work OK till my next service check where I will pick up that there is a problem. Strange about the bung not sealing though. I do like Fibre washers or copper, never been a fan of Ally ones. Link to post Share on other sites
Guest Posted September 29, 2011 Share Posted September 29, 2011 I always thought bilge dust was a myth!!!!! Link to post Share on other sites
Guest Posted September 29, 2011 Share Posted September 29, 2011 Yes can't check enough. I was taught to check the engine oil partly because the level may rise due to ingesting water. Link to post Share on other sites
idlerboat 116 Posted September 30, 2011 Author Share Posted September 30, 2011 ...Hope you are right wheels...The thought of having to rebuild the box fills me and my pockets with dred...as to the ally washer...beats me ! Short of polishing the face of it I cant figure why else it leaks. It is more an oooze than a leak, but nevertheless it added up to a big oops. .......dust and dog hair...... unless I leave the hatch open when it rains or spill something... Link to post Share on other sites
wheels 543 Posted September 30, 2011 Share Posted September 30, 2011 I always thought bilge dust was a myth!!!!! Not if you have a slipping Drive Belt. Link to post Share on other sites
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