It isn't lack of grease that blows couplers its lack of alignment.
Get an alignment tool - your engine is WAY off.
Here is your first comment. If you want to be a part of the team around here to help solve issues for those of us "Backyard" mechs who try to learn themselves, your first post in the thread should have read something like,
Bad/sagging motor mounts in the rear can cause alignment issues which are difficult to check with the stock Merc tool.
If you work on these as long as you have, you know that is not the most common issue for blowing couplers. These guys still do this for a living, and have for years. And some work on the race boats all over the country, they are not stupid and have saved members thousands of dollars by donating their time and expertise to the site.
Geranimo - It seems that I know more than the EXPERTS.
Wanna bet your thousand bucks on that one????? I'll have my certified Merc mech write the test and send it out.....
ALL that I work on are HIGH PERFORMANCE boats.
You should reword that to, when I'm working on boats, and not working on my business.
I am not the one name calling.
I've really seen no name calling, but as I said about post 2 above, stating you know more than the experts is gonna start issues.
In the meantime, think about it and see if you agree. Everyone with expertise to help is welcome, but we all try to work together to a solution by asking, "what if". If you are saying a sagging rear mount, aligned by lowering the front mounts, is the only/#1 cause of coupler failure, I'd bet you're wrong.....