4.3 engine mounted raw water pump inquiry

[Scott Danforth]

I do realize this, thanks for reminding me of it, but how many of those millions of them find themselves hunting 1/2 mile out in Lk MI in mid winter with their nephew in the layout boat 200yrds away when Lk MI winds kick up, shift ~90* and start throwing 3-4' rollers at you that are starting to break and smoke is rolling out of their doghouses. And then find the "new" 2yr old OEM impeller might have been "stale" past its sell by date that might have ruined a new 3yr old motor? Situations like these leave lasting impressions. Thus exploring the idea of getting a reasonably easy & quickly serviceable impeller in the boat. So, trying to understand how swapping a Bravo for this already inplace Alpha would be less work and cost than an ~$200-300 pump, some hoses and some custom brackets/plates made in house in my machine shop?

a $30 water pressure gauge would have told you not to leave the dock

 

[76SeaRay]

This may be an invalid thought but would both pumps in a Y configuration give you a "backup" water flow if one fails? That is, if the impellor in the seawater pump fails, the lower unit pump continues to cool the engine at least somewhat and vice/versa? Just a thought to ponder.

 

[Scott Danforth]

This may be an invalid thought but would both pumps in a Y configuration give you a "backup" water flow if one fails? That is, if the impellor in the seawater pump fails, the lower unit pump continues to cool the engine at least somewhat and vice/versa? Just a thought to ponder.

thats an @kenny nunez question

 

[kenny nunez]

Several posters on the Donzi/Bravo site that were having overheating problems solved them by going through the bottom of the hull.
As already said the crank driven pumps will pull more water than the drive pump especially as some crank belt driven pumps are overdriven.
While the V8 drive’s water pumps are also overdriven the 1/2” pipe will only flow a limited amount of water.

 

[achris]

This may be an invalid thought but would both pumps in a Y configuration give you a "backup" water flow if one fails? That is, if the impellor in the seawater pump fails, the lower unit pump continues to cool the engine at least somewhat and vice/versa? Just a thought to ponder.

If one of the pump's impeller loses its blades, the other pump will push ALL its output through that pump (not the engine). If you want both pumps to operate at the same time, as backup for each other, you'd need to put a high flow check valve in the output line of each pump...

Chris...