Gearbox on Swan 41
We have water in our gearbox (original Borg-Warner) with badly emulsified oil. Any clues as to how this might be happening would be welcome. Also can we dismantle the gearbox without removing the engine (access from the aft cabin seems quite good)?

Rob Ellis

Swan41 'Jaka'.

Dear robellis,

On my previous boat I experienced the same problem.  The mechanics all told me that engine and transmission were worn out and that I should repower.  Well, the water had gotten in from the top at the dip stick, so, with a few "baths" of ATf and changing every 10 hours 3 or 4 times, the transmission was fine.  I did send samples of both the ATF and engine oil away for analysis until a trend was established and I was certain that all was fine.

So, the first step is to determine how the water got into the transmission.  Then, contact an oil analysis firm and ask for recommendations about number of samples; etc.

Chris

We had the same problem, but it came from the transmission cooler which had developed a hole (winter frozen??) and allowed sea water in the oil of the transmission. This, incidentally was detected as a lady sunbathing on the deck while we were under engine, saw some kind of "yoghourt" droplets in the water coming out of the exhaust. The oil in the transmission was a nice pure white emusion.
Remedy was first to isolate the oil cooler (black 60mm diameter & 50cm long tube) sitting on top of the transmission, and change the oil. We came back home avoiding use of the engine (as obviously the transmission was heating a lot.
When the cooler was repared we changed the oil again, and since then everything is fine (but a bit noisy...).
The question is finally how long was your transmission lubricated with the sea water mixture...?
Kind regards and fair winds.
Philippe V/ 41/022

Thanks for those helpful responses. We have now identified the problem as the gearbox heat exchanger and an excellent French mechanic (we are in at Sainte-Marine in Brittany) has got hold of a replacement which he is currently fitting. So lots of oil baths for the transmission and crossing of fingers.

Anyone know whether we can get the gearbox out without lifting the engine?

Same problem in my 411 with a Perkins 4.108 due to a failure in the heat exchanger raw-water/ATF-fluid.
I changed the heat exchanger, flushed the transmission with new ATF fluid untill the fluid remained red (something like 5-6 times) and that was it. It happened 8 years ago and I have had no problem since.
To unmount the gearbox you have to: undo the shaft flange bolts, take care of the wiring/tubing, put one or two strong wooden planks under the engine, unscrew the bolts that keep the silent blocks fixed to the hull and pull the engine forward until you have access to the gearbox.
A tackle from the boom is a handy help.

Daniel, 411/004

Thanks for that Daniel. We are back in our home port now, and the transmission seems fine. The oil will be changed again (and again).

Rob