View Full Version : Raw Water GPM

04-24-2013, 12:16 PM
I'm wondering how much raw water flows through a 360 at idle. I know there are some that have "T'd" into their raw water line and use that line stuck in a 5 gal bucket of fresh water to flush. Has anyone timed how long it takes to empty the bucket?

05-01-2013, 12:30 PM
I guess no one has timed this. I am in the fiberglass repair and repaint process right now but after that I will give it a try and report back so that we all know. My thoughts are designing an easy to use built in fresh water flushing system for raw water cooled engines. So easy, in fact, that it gets done after every time the boat is ran. I've got some ideas, some a little out there, for this system.

05-01-2013, 04:49 PM
Groco already makes a flushing Tee for their strainers...as far as volume goes, it isn't too hard to get the open (zero head) flows from most pump OEM's...of course, most use a "new" pump (no wear) and its output varies with RPM...

What actually goes thru the engine will be driven by the restrictions (age and corrosion) in the rest of the cooling system passages...

05-01-2013, 06:42 PM
Thanks Macomark. That makes sense that there are a lot of variable that go in to the volume. I guess I need to do the test on my own particular system anyway for an accurate result.

05-02-2013, 09:51 AM
As far as testing goes, a good point of reference comes from Sherwood....using their popular 10615 impeller, with 300 hours (one year of active use), they expect the pump to delivery 7.5 GPM at 1000 rpms and zero head (output unrestricted; ie open hose with no lift).

That is a reasonable test for the pump...as far as the rest of the system goes, you can a low pressure gauge towards the outlet of the system and look for any pressure rise to assess cooling system degrades...I think FastJeff has posted a few times on what he has seen...

05-05-2013, 06:00 PM
Had the outlet of the raw water pump off at one time. At idle the water barely ooozes out. Rev her up, though...