2007 MFS18BS Lower unit

Hi all,
This is my first post Been lurking here for years. Always found my answers and tips till now in previous posts. Anyway just got a new to me boat with the above motor. Boat has set for a few years. The guy sayed it needed a water pump impeller. Sure enuff it does. I have replaced these before on evenrodes and johnsons. even a suzuki. So i figured this one was no problem either. I took the pin out of the shift rod, took 4 nuts off the lower unit studs. Did the knock the lower fin to the side and nothing. I have done everything but blow it up and still will not seperate. checked for hiden bolts and found nothing. So my big question is what am i missing or is it just stuck solid from setting? can i drive something thin between the 2. (scared to do that) I did beat on it with a rubber mallet. Put some penitrating oil on the studs. Still stuck? Help please

Should just be the 4 studs. The splines could be stuck in the crank. Wedges, time, and patience should do it. Don't pound on it, because you are likely to crack the antiventilation plate.

Do the complete wp kit instead of just the impeller.

I was thinking of using a wood wedge of some sort to maybe tap down into the crack. Then I saw your reply. So I will try that tonight and if its still a pain. I was also thinking about just taking it in to the dealer. If they bust it its on them. Only thing is down here near the beach they are usually backed up. I might get it back in a month or so. I already bought the pump kit also. We will see.
Ill let you know how it goes.
Thanks

Well last night I started my motor abuse. The thing is stuck good. I beat and beat and it would not budge. Now around the seem it looks very bad. Anyway I did punch threw it on the side toward the propeller. The metal is very thin all the way around. It broken threw into the exhost chamber. Any other subjestions other than beat it up and replace the housing. The upper and lower case overlap at the joint. I can get the case for 300.00 just dont want to spend that.
Thanks

The LU case does not overlap the exhaust housing. Since you already damaged the case, you will need another.