Replace rear seal on transmission 7.4 L inboard mercury

jase34242

Cadet
Joined
Jun 3, 2023
Messages
19
Same old story - this time it's my turn.

Bought an old boat (1997 37 ft Egg Harbor Convert.) to use as a liveaboard in the FL Keys, 1 year into ownership I end up getting a great deal on an apartment (unbeatable deal). I start thinking about selling it, put it up for a pretty cheap price (20k, negotiable, hoping for 15k) and on the very first test run of the motors for a prospective buyer, she develops a trans fluid leak.. I've run these motors without issue right until it comes time for sale. Gotta love that! I'm not mad, but just love the timing. I will most likely be pulling her out of the water to get the bottom paint re-done, etc.. however, does anyone have any guidance on how big of a deal this is? I've done some regular research and find references that it can be done without pulling the motors and then other sources that say motor must be pulled. If the motor has to be pulled it might be time to just fire sale the boat and take the hit as it's costing a bit to keep it in the water each month. While I enjoy hanging on her on the weekends, I really don't NEED her anymore. Hell I'd even just let someone live on her if they cover the slip cost at this point.

So what's the verdict, pull the motors for this rear seal replacement or can it be done without that hassle?

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Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,474
the rear trans seal can be replaced without pulling the motor IT AND ITS A BIG IF you can slide the prop shaft back far enough to remove the coupling from the prop shaft. Last one I did this way was to remove the prop first because it hits the rudder
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,367
Yeah, done a few of them over the years. As said, clearance is the key. If you can gain the clearance you will be happy. Others are a bear to get to. Even sliding the engine ahead works on occasion. Removing the prop shaft don’t always work without dropping the rudder. Had a couple that you couldn’t even change the stuffing box seals without moving the engine!
 

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,475
Just a suggestion after the coupling is removed, get a Speedy sleeve which is stainless steel and the transmission seal will last a lot longer.
 
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