Leaking rear seal

[nesdon]

I bought an early Tartan 30 with its original A4. The bilge was very oily, and after topping off the oil, found it running down the rear flange. Obviously need a rear seal, but also have a growl when in gear, likely the rear bearing.

The slop from bad bearings often lead to bad seals, and given how low the oil is in the gearbox, a bad seal might lower the oil enough to kill the bearing. So I’m planning to pull the rear cover and replace the seal and bearing. Anyone have any tips or warnings? Im a very experienced auto mechanic but never been inside and A4, though have fought with the fuel system a few times.

[Peter]

nesdon,

I had a leaking rear seal and it was noisy in gear. Replaced seal and bearing and I was amazed how quite it became.

I found this resource to be incredibly useful - link is to Windows version - there is also a Mac version.

https://moyermarine.com/product/video-tech-tip-oilsealwindows_clip_01_568/

Before ordering parts you may want to get things apart - if the output coupling is not in good shape it can also lead to deterioration of the seal.

Good luck with the job.

Peter

[nesdon]

Thanks for the tip. I purchased and watched the video. I was a little disappointed that there was no mention of the second bearing visible inside behind the output bearing, but I'm going to assume that my repair will follow this common fault case.

I will hold off on getting parts until I have the flange in hand and can decide if it needs to be replaced, meaning I'll probably wait until I'm on the hard for the winter before attempting.

One great thing about the Tartan is the engine access. It's placed amidships under a large cover so that the gear box is completely exposed. The prop is also directly behind the keel, so I expected I could undo the coupling and slide the shaft back more than enough to remove the flange even while afloat. But I think I'll wait for winter and live with the oil leak for the rest of the season. Then I can pull the shaft, check the cutless and san pedro tube, and make it a whole reconditioning of the drive.