ATF fluid leak

Miles Bidwell <mbidwell@...>

Hi DoodelBug,

I am not sure that this will help, but it might. Two years ago I thought
that I had a leak from the drive shaft seal. The tell-tail red ATF fluid
brought visions of very expensive repairs.

I took the boat to Amel in Hyeres. The mechanic looked at the ATF fluid
dripping down from the joint between the engine and the transmission and
said that he had to go get another tool. He returned with a mirror. After
a minute he stood up and, with a big smile, announced that that leak was
from the shift leaver on the side of the transmission. The fluid was
running down under the transmission so that it appeared to be from the
drive-shaft seal. He said that he could replace the shift leaver seal in
about 15 minutes and he did.

This winter I will sail back across the Atlantic to the US. I will miss the
Amel maintenance. Even worse, I will have to relearn how to do this stuff


Miles Bidwell



SM#331 has the Yanmar 85 HP engine with a ZF Hurth model HSW 250H – 2.8
transmission. The latter has had a small leak of ATF fluid from the
output drive shaft seal. I had a VERY expensive repair made a year ago
with a 45 mm "speedy sleeve". It made no difference whatsoever. The
leak is noticeable under the transmission but I have never had to top
up the fluid between routine servicing. It has been suggested that the
reason that it leaks is that there is no "breather" on the
transmission. It was further suggested that any device that needs a
cooler, should have a breather as no seal is going to withstand the
pressure build up. Has anyone had this problem? Has anyone added a
simple breather?