What shall we do with the rusty coupling?

oilybilge

oilybilge

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After seven years in the damp bilges of my wooden boat my shiny split coupling looks like this. I thought I'd better have it off while I still could. The gearbox flange is just as bad.

I know most of the rust doesn't matter, it's just an eyesore, but I'm worried about the mating surfaces where the R&D flexible coupler sits. Aligning the couplings involves tolerances of .25mm, and at some stage the rust will start to make a difference. Has anyone got any thoughts about my best course of action? My idea to get rid of as much of the rust as possible without harming the metal, then slathering it with some heavy duty anti-corrosion stuff, and hoping for the best. Any advances on that?

IMG_1966.jpeg
 
The problem arises from modern engines' unfortunate tendency to not leak oil or diesel as much as traditional ones. ;)

My coupling (traditional, non-Aquadrive type) looks similar to yours from the outside. I've never seen the inside since it's apparently been successfully doing its job for the last 47 years.

oilybilge said:
. . . Has anyone got any thoughts about my best course of action? My idea to get rid of as much of the rust as possible without harming the metal, then slathering it with some heavy duty anti-corrosion stuff, and hoping for the best. Any advances on that?
Click to expand...

Sounds a good course of action. If you felt more motivated you could paint it before applying the anti-corrosion fluid.

Don't forget to grease the bolts before reassembly. Getting those apart, should I need to, is my main worry about my coupling.
 
I dribbled engine oil on mine last year. This year I followed up with sunflower oil and abraded the bits I could get at with aluminium.

I noted what seems to be a split in the flexible plastic bit of the coupling.

I'll probably take it apart to replace that, and for a more thorough rust treatment job in the future, if there is a future.
 
Boater Sam said:
I have 5ltrs of Phosphoric acid on the boat, stuff that looks like that get dropped in it for a couple of days. Comes out black and rustless ready for paint. Doesn't rust again for years.
Taught it a lesson!
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Genuine question not trying to trip you up. - Once you've removed object from the acid, do you wash in water and allow to dry before painting or do you paint straight from the acid wash once it's dried off?
 
Thanks for all these excellent suggestions, chaps. Exactly the sort of low-effort solution I was hoping for. Now I'm off to investigate the 'acids' section at the local supermarket.
 
A few years ago I removed our coupling and took it to a paint shop in Southampton. I asked them to clean and powder coat it. To make life easier for them I said just use whatever colour is in the gun, fortunately it was silver, not pink! Cost a tenner, which went into their tea fund.
Allan
 
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