I have read allot of bad things about the 3.0 liter 300X and the sportmaster lowers but most seem to be on CATs.

Hows the relaibility on V hulls?

My son has a set of Pro Max's on a 28 Skater with sport master lowers, they do not like to be surfaced especially with 3 blade props. Running 4 blades and at a lower height they seem not to get as much water in them. A friend has a Concept with twin 300X's and he broke a gear case on that, but attributed it to driver error.

thanks I know the old problem with getting water in them I have 2.5.s now and One thing I found that helps ALLOT is draining about an ounce of gear lube at fill up. That keeps it from ecxpanding and popping the seals made a big difference in my 2.5's

I still check the oil every time i run the boat though.

i have a pair of 300x's on a v-hull , that's exactly what happened to me when i first got the motors. shift shaft pops-up and water in the lower, once i started doin what u are doin to your 2.5's, i didnt have any problems since. i to check the oil after every run, it's cheaper than buying internal parts for the sportmasters.

Its nice to know we can count on mercury to learn from thier mistakes.LOL

Did you try expansion tanks yet?

so have you had to change lube every time or do you just check it somehow?

I got to the point where I have an electric fuel pump and a tractor battery hooked up witha resevoir and I just pump new fluid in it almost every time I run the boat.

I may do expansion tanks on the new 300X's Youd think they would have cured these problems by now especially at the cost of a set of X's

from what I understood the reason they get water in them when surfaced is that they get hot. Then they expand the gear lube which pops the seals then when it cools coming back into the dock it sucks back in the cool water just like an overflow tank on a cars radiator.