Relocate water pick up through hull....Al, can you help???

[jahman311]

I have been struggling with a constant overheating issue in my salt water 6.2 merc w/bravo 3. I can accelerate to about 3500 rpm and watch my temperature gauge start climbing. It cools down once i let off to about 3000 rpm. I noticed that the pick up hose inside the boat coming from the transom was sucking air and was badly corroded. I replaced the bushing inside the hose (which was collapsed) and changed the impeller. I took it out last weekend and it ran great, planed out and i was running about 4500 rpm. After about 10 minutes, i saw the temp starting to rise again. I am trying to figure out what could be making it overheat. Bad sensor/guage? My mechanic says that i should bypass the lower unit and drill a "pick-up" in the hull to ensure the engine is getting sufficient water. Thoughts on this??

[alswagg]

Well, do not bypass the outdrive, as the water flowing through the gear case is what cools the gear case.  However, you can install a dual water pick up.  I have done this on several hi speed hulls.  You will need a        1 1/4" hull pick up, ball valve and Y adaptor.  I would also prefer to see a sea strainer also.  You must utilize the OEM pick up through the gear case or sever damage to the drive will occure due to over heating.  Once you do this, make a note that the interior ball valve will have to be shut off while flushing the drive and engine while on the hard while utizing the gear case pick up.  Or you can install a flush kit and flow water into the system prior to the sea water pump.  I commonly do this on boats with this system.  Al