Oil leak from Bukh DV20 Gearbox

[Finbar]

Over the winter the oil seal at the output shaft on my gearbox (attached to a Bukh DV20 ) has failed, and I have a steady oil leak. The boat was laid up, so could have been the extreme cold. Anyone replaced this oil seal? I particularly want to know if I need to take the gearbox out and get it on a bench, and if this can be done without shifting the engine.

Do I need to break the gearbox to get at the seal to remove it? I am working to a deadline as the boat goes back in on Easter Sunday.

All advice based on experience gratefully received

 

[VicMallows]

I can answer your question in great detail in respect to a Sadler29 ! (BUKH 20). A Sadler32 may be a bit different in terms of access but I would guess essentially the same.

No, you don't need to separate the gearbox to replace the rear output shaft oil seal. All you need to do is separate the shaft coupling; undo the nut attaching the the gearbox flange to the gearbox output shaft; withdraw the flange; prise out old seal; replace.

First difficulty is likely to be undoing the flange nut. Originally it was staked into the shaft . The mild-steel nut may have rusted. You need a good socket wrench with a long lever, and need to make up some form of holding bar. Whatever some people may say, the nut has a 'NORMAL' (RH) thread. (ie, turn anticlockwise to remove). My nut just manged up. I eventually removed it by drilling holes in the nut and using cold chisels......all done with mirrors in very confined space. (I now have great respect for dentists).

From now on easy!... the splined flange just fell off; seal replaced in minutes.
You will need a new flange nut. Be prepared for an eyewatering price from BUKH. The thread is metric-fine and although unusual, you should find S/S ones on EBAY for a few pounds (they seem to be used on LandRovers). I just used a strong grade threadlock rather than staking which has been fine for several years.

PM if I can help any further.

Vic

 

[rhumlady]

How do you get a part that is used on a Landrover for a few pounds? A few hundred surely?

 

[Finbar]

Thanks Vic, just what I needed. Will pm you

 

[onespeed]

Hi, please can anyone tell me the size of the metric fine nut on the end of the gearbox output shaft. About to do the same job (change gearbox output seal) on a Sadler 32 with a Bukh dv24.

Thanks
Simon

 

[VicMallows]

It's M20 metric fine. All the other details of replacement in my post above. (I see that was 7 yrs ago, and yes, everything is still fine).

 

[onespeed]

Thanks Vik -that’s very helpful. Going to buy a spare but before starting this job based on your experience...