Yanmar KM4A gearbox

[kilmaine]

When I turned over the engine recently raw water came out of the gearbox filler! It seems the oil cooler had sprung a leak. I have removed the gearbox and ascertained that the copper/brass outer tube of the oil cooler is leaking into the box. This part is shown as a separate item to the casing in the parts book but these is no clear indication how to remove it. Has anybody managed this and if so how? Also having removed the gearbox I find the splines input shaft extremely tight to turn which doesn’t seem right to me. Can anyone confirm this? Thanks

[skipperpete]

Ease the o ring out of the groove , then the spacer, then the next O ring and you should be able to move it enough to free up the other end.
The transmission being sticky is a more pressing concern, it probably has corrosion on the bearings as well as the clutch cone and gear surfaces, especially if she took on salt water. It’s a very easy reversing gear to work on but you’ll need a special wrench for the gearbox output flange nut.

[kilmaine]

Thank you I will have another go. Luckily it cant have sea water in t as only been operated on the non tidal Thames.