Seawater pump change out

[CHIEFRAY]

Looking to change out my Seawater Pump on a 5.7 L MerCruiser. My question is does the water inlet valve have to be shut off to do this swap seeing as the engine is not running?

 

[Cigatoo]

If the pump is above the static water line no need to shut off the seacock / “water line valve”

 

[sunchaser]

My experience with many Mercruisers. If the pump pulls water through a stern drive lift the drive out of the water provided the drive doesn’t re- immerse a bit with a change in trim due to body weight.

If the pump pulls water through a hull valve likely yes, - this arrangement should have a strainer after the valve.

Is the pump bad or just changing impellers?

 

[CHIEFRAY]

Pump is bad.

 

[Gdavid]

My experience with many Mercruisers. If the pump pulls water through a stern drive lift the drive out of the water provided the drive doesn’t re- immerse a bit with a change in trim due to body weight.

If the pump pulls water through a hull valve likely yes, - this arrangement should have a strainer after the valve.

Is the pump bad or just changing impellers?

The bravo models have a belt driven raw water pump rather than the outboard style of pump in the lower units used in the alpha models

The water inlet valve should be closed, the pump is located down low, almost certainly below the water line.

 

[sunchaser]

The bravo models have a belt driven raw water pump rather than the outboard style of pump in the lower units used in the alpha models

The water inlet valve should be closed, the pump is located down low, almost certainly below the water line.

Correct you are GD.

Happiness is successfully changing the Alpha drive impeller in the water, far from the trailer, stern to a sandy beach and a cooler of beer.

 

[tiltrider1]

Looking to change out my Seawater Pump on a 5.7 L MerCruiser. My question is does the water inlet valve have to be shut off to do this swap seeing as the engine is not running?

I find this an odd question. Why wouldn’t you close the valve for safety reasons. Unless your valve is stuck and you are asking if it can be done with out closing the valve. In that case, I wouldn’t try it.

 

[C lectric]

Shut the valve off. Even if it is above water level the question is how much above. If minimal and the boat is rocked enough the boat could start to take on water and when there is enough, sink or at the very least damage a lot of other stuff.

 

[CHIEFRAY]

Thanx All for the input, I think it's better to be safe than sorry so I'll shut it off before replacing pump.