So I put my formula in the water for a run for the first time... Picked up the boat a few weeks ago (311 sr-1) with 454 's and fresh water cooling. One side of the hull was bubbling - kinda like an exhaust (smoke n bubbles) Let it idle a few mins and she started overheating ! Shut her down n pulled her back out. I assume the one side of the hull bubbling was the impeller messing up. (hull water intake) What is the procedure to replace the impeller ? What's my worst case scenario if it's not my impeller let's say... Could it be another part of my cooling that went faulty ?? It's an 89'and not sure what was and wasn't done on this ... Looking to get ideas / opinions on what to do from here - first thing I guess is to inspect the impeller but how do I do this ? Do I unscrew the entire pump out or ??? Will this drain all my antifreeze out of the block ? Any ideas greatly appreciated !!

I had almost identical scenario. Sounds like the raw water intake hose and exit hose from pump were installed backwards. Visually check hose routing by looking at the good motor. Probably didn't hurt the motor, sounds like you caught it pretty quick. You should not have to drain antifreeze to change this impeller. It is a pretty easy job if you can get the pump off easily.

Here is a great detailed thread on changing a sea pump impeller. Still do not understand why it was never a sticky on the top of the page.

http://www.offshoreonly.com/forums/g...-impellor.html