TMC 40 gear box oil leak

[waterbuffalo]

I have managed to wrap an electrical cable around the output shaft of my TMC40 gear box.

Having cleared the cable away I am now left with a leak of ATF from the shaft seal.

Is there an easy way to replace this seal or do I need to remove the gear box etc from the boat? (attached to a Beta 20).

Or is there a good temporary fix?

 

[vyv_cox]

Unfortunately for you there is no simple or temporary way of fixing it. If the flange can be removed from the shaft easily, dependent upon design, you should be able to replace the seal in situ. The actual seal replacement is a doddle, should take about five minutes.

On most boats access at the back of the gearbox is so poor, with shaft and stern gear in the way, that lifting it out may be the only way. A half way method might be to lift the back of the box, leaving the engine mountings in place.

 

[RobbieH]

Sorry to resurrect an old thread but I have a related question. Does someone know if the seal on the shaft is a push/interference fit from the outside or does the gearbox casing have to be split to replace it? I have good access to rear of the gear box and I can slide the stern gear (flange, clamp and shaft) back about 20 cm befor it hits the skeg.

 

[earlybird]

From a cross sectional diagram that I have, the oil-seal appears to push into the gearbox housing from the outside. To access the seal, the output shaft drive flange nut needs to be removed, followed by the flange itself, which appears to be splined onto the output shaft, so should pull off easily, the ID of the seal runs on the drive flange. The seal can then be prised out.
It therefore seems that the job can be done in-situ.
I've got a TMC40 'box on my Beta, but I've never tried this, so can't vouch for the details.
Hope this helps.

 

[doug748]

I changed mine once a simple job, as described.


One point though. If the gearbox filler cap screw is loose or missing it's washer, or it the dipstick is not pushed fully home or the rubber gromit is damaged, you can get leakage which can lead you to suspect the seal, as the errant fluid runs to the back of the gearbox.