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Old 08-21-2013, 02:19 AM   #1
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Default 2003 mercruiser 5.0 bravo 3 impeller

Hey Gang,

I have been given mixed messages about whether I need to pull the boat out of the water to replace the impeller - seems to be a no but some say absolutely yes. I have only found one stopcock which is for the head and apparently there is another one? Anyone have some solid input on this?


James T

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Old 08-21-2013, 01:21 PM   #2

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You can pull the inlet hose to the pump and either clamp it (first) or plug it after pulling it. If you clamp it shut first very little water will spill, but you will get some water into the bilge when whatever water is still in the block drains out. If you clamp/plug it after you'll get more but still not enough to worry about, and certainly not if your bilge pump is operational.

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Old 08-21-2013, 03:21 PM   #3

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Alpha's have their impellor in the drive itself. Some may be confusing this with ALL Merc outdrives, which it is not. You will get water in the bilge, particularly if you don't plug the hose and clamp it.
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Old 08-21-2013, 11:07 PM   #4
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just clamp or plug the hose, no need to take the boat out of the water.... if you lift the hose above the water line the water won't come in.
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Old 08-21-2013, 11:31 PM   #5
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Change mine every 3 years in my 3000 scr. Really very easy if you are handy with a wrench. Get a clymer service manual and it will show you step by step.

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Old 08-23-2013, 11:00 AM   #6
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B3 has an inboard raw water pump. There are 2 hoses 1 from the transom assy (raw water in) the other is the pumps output and goes to the t-stat housing. You need to pull both and I would plug the inlet hose with a emergency plug you can get from any marine store. Remove the belt then remove the 2 bolts holding the bracket to the engine, this will allow you to remove the pump assy from the engine and work on replacing the impeller topside. Be sure to reconnect the inlet and outlet hoses correctly (where you took the off). May want to mark one with a piece of tape.

You didn'y say what model boat you have but cruisers have 2 seacocks, 1 for the head the other for the AC.

Live long and prosper James T

1997 2400 SCR
5.7 Vortec / Bravo 2
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