Water pump or no water pump?
 

1996 merc 5.7 mag gen + motors. 300hp

Question: I had a place umplug the motors while I send them off to the builder. The place that is putting them back in is wanting to get rid of the water pumps on the front of the motors. He says there not needed because the sea pump will do it and it will take less stress of the motors not having to turn the pulleys. The oil temp runs hot so I'm adding oil coolers. Water temp was never a problem. He showed me a kit that you can put on to eliminate the pumps and showed me BB blower motors sitting in his shop that had this kit with no pumps. Should I or should I not?

For what you have, I would say NOT and keep the engine water circ pumps. They will provide more consistent water temps and pressures.

Crossovers systems can cause problems with high water pressure.

KISS.

Keep the recirc pumps.

Less stress ? LOL.

So do you have an alpha or Bravo outdrive ? If alpha then 100 % you need water circ pumps. If bravo many run without / cross over and many run the circ pump. I like using and running the circ pumps.

I believe he's got factory EFI also...all the more reason for factory recirc set-up.

^^^^ That would be 100 percent correct SB. Over cooling or under cooling the engine - the coolant temp sensor inputs to the ecm will be out spec per stock OEM cal and that also will change Idle control. Also Idle control is important for shifting the outdrive - N to FWD ---- N to REV and so forth, plus important for no wake zones, docking, loading the boat on the trailer and so on. Even correct Idle control is important for engine shutdown in the water so the engine does not diesel and reverts water.

Blackhawks 1:65 31p

I didn't like the idea of removing them that's why I thought I would research here. ��

Blackhawk for your app - those recommend a idle of 600 rpms only . ^^^^^

Good hunch, sounds like the shop is trying to make extra profit with no real benefit to you.