Good tips !

Also, remember colder fluid flows slower. Gear oil from inside your AC'd house is much slower than gear oil stored in hot temps.

Big time !

New yellow gasket sealed the leak. Funny as a new blue one leaked, then put in a used yellow one that looked fine it leaked. New yellow no leaks. Glad the boat sat for a while before I put it in the water.

Ah forget it - this plug was brought up earlier in thread.

SB you changed your post I do not miss too much and posted it in # 15.

You can not use this gasket for Merc apps. Also I will order this next week and see how well it works for Mercruiser and if the Mercruiser gasket will work correctly with the Sierra drain plug. I will let you know soon.

That's why I changed the post.

Yeh, that would be cool if you find out. Could be a sweet option.

Ordered the sierra 18- 4249 allen drain plug screw. Nothing special and will not work as external drain plugs for Bravo III or alpha's plus it over hangs a lot using it for the vent hole plug. The head is twice the thickness compared to mercs drain plug so it sticks out and does not deep set ( flush ) into the vent hole in the upper drive section.. Looks like an after thought for using as vent oil plug screw

Also the magnet is weaker than merc's to catch any metal material. Also there is not as many threads as the merc drain plug to screw into the drain hole. IMO I would not use it. Also the allen head is very small and is harder to stab than the merc slot drain plug because the allen wrench is so small and not as long as a screwdriver.

I can careless about using it for any merc apps. Just an update on it as I had a chance to see what it was all about. Nothing special plus again it will not work for Bravo III or Alpha drives as it wont screw in far enough to seal the drain hole..You will leak gear oil using it for those apps. I know I tested it plus for the Bravo III it barely screws in. FYI Good luck.

John, you must have sucky Allen wrenches.
Nutdriver anyone? T-handle? Bueller?

JK!!
Thanks for the investment and report.

And for the drain plugs - magnet end of it was testing the brand new Sierra 18-4249 against a 2004 magnet (Mercruiser Bravo 1 ) The Mercruiser 11 year old drain plug picked up more washers everytime and then next test was - positioned the 2 drain plugs at 3 and 9 o'clock - metal washer in the middle and pulled both drain plugs apart evenly - everytime the new Sierra drain plug pulled away leaving the 11 year old Mercruiser drain still stuck to the metal washer. I even change positions of the drain plugs from 3 & 9 o'clock to 9 & 3 and still the Sierra pulled away .

Today I had a Alpha gen II and Bravo 1 and Bravo III all next to each other working on them plus all 3 had gear lube changes so I decided to test the Sierra 18 - 4249 in all 3 apps.

If anyone wants it 10 bucks to your door - it is brand new as I just pulled out of the package today.

Thanks for the update BUP. Good info.