CIG3

Was thinking of removing the circulating pumps on my 600sc's and going to cross-overs. any words of wisdom.

Griff

If its not broke, don't try and fix it. IMO, its not worth it.
You could end up with water temp, oil temp and water pressure problems.

ThisIsLivin

If done right it may save 15-20 hp. It's one of those things you do if you are bored and a freak about every hp. Which explains why I have a crossover. But you better be ready to monitor everything and love to tweak.

35fountain

Depending upon where you do your boating. Are you putting a crossover in with a thermostat or without? If you boat in waters that are cold in april /may 45-60 degrees..with the thermostat crossover bypass system, you will have fluctuating water temps because the hot water underneath the thermostat housing wants to open the thermostat BUT the bypass tube that runs from the crossover to the stat housing is pushing cold water on top of the thermostat for the bypass which is causing the thermostat to get confused. Drilling holes in the thermostat will help it a bit but will not solve the fluctuation. You will see your temp gauge moving alot. After the water temp in the lake /river warms up there will be less fluctuation. If you run the crossover without the thermostat, this will cause condensation especially when the water temps are cold, low oil temps which you may have to install an oil thermostat housing or cooler thermostatically controlled and you may end up with milky junk under your valve covers.
I know this from my past experiences and I put my circulator pumps back on ...If you boat in waters that are a constant 70-80 degrees year round you will be fine.

Oh I left out water pressure problems especially with thermostat crossover system. This is why..The thermostat housing with the thermostat system has 3 ports.The tube from the crossover that replaces your circulating pump has another tube for the bypass hose. That bypass hose connects to the thermostats housing center hose port. That hose i believe is not bigger than 5/8". The other 2 outlets on the thermostat housing are 1" and they connect to the bottom of the exhaust manifolds. The center port of the housing ( if you could look inside it) has a little lip that is supposed to direct the bypass water around a super tight bend in the housing directing the bypass water equally to each outlet port that lead to the exhaust manifolds. This is what creates major water pressure. The Mercruiser seawater pump puts out 38 gallons a minute @ 3000 rpms..There is no way that 5/8" bypass hose could dump all the excess water thru that small hose and as i said before the lip inside the thermostat housing. No Way.... Now your water system is in a way restricted which in turn builds up pressure. If you can't dump the excess water then pressure builds up. When i had a bypass on my boat with the t'stat system my water pressure was exceeding over 25-30 lbs. I then needed to install a dump valves on each engine. The stock circulator pump maintains constant water temperature no matter what the incoming water temperature is and it has the correct bypass built into the thermostat housing to dump any excess water.

IN MY OPINION.......NOT WORTH IT...LEAVE IT ALONE. ITS DESIGNED TO HAVE A CIRCULATOR

CIG3

Thanks for the sanity check. I'll leave it alone.