Impeller Replacement on 2005 350 Mag MPI Bravo 1

[Squire]

Help!? I am tasked with the impeller replacement on my sterndrive this weekend and I have a question. I have researched the procedure for the seawater pump removal and although I have found some useful resources I still have reservations. There are two recommended procedures that involve either complete pump removal or disassembly of the pump housing in place (doesn't require disconnection of water lines at back of pump).
The question arises from removing the entire pump and identifying the additional small lines that attach to the pump body forward of the water supply and return lines. These attach to the upright part of the seawater pump that resembles the master cylinder of a brake system. Are these for the fuel cooling system? Are they easy to detach and re-attach or will I need gaskets/O-rings if I attempt this? Is it better to completely detach the pump or disassemble and reassemble it in place to replace the impeller?

 

[cr2k]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

I have always found it better to remove the pump. It is easier to take apart when you can hold it in a vice. You also have the chance to inspect all of the housing, etc. As for the lines Just mark one of each kind (large/small) and go for it.

 

[Squire]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

Thanks but can anyone tell me what the small lines are? Am I going to spill fuel when I detach them?

 

[TilliamWe]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

If your boat is an MPI, it shouldn't have any fuel lines going to it. Those lines should only be on carbureted engines, as the fuel pump is integrated with the seawater pump. MPI has it's own separate fuel pump down on the port side of the engine.

Regardless, I always prefer to remove the entire assembly, that way I can work on it on a bench or is a more controlled environment. Just remember where you take the really STIFF hose off from (top or bottom). Don't want to reverse them or you'll ruin your impeller when you restart it without water.

 

[Don S]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

Do you have the air actuated drain system with a closed cooling system?
It's what it sounds like, if so, those are air lines, not fuel lines.

 

[TilliamWe]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

Do you have the air actuated drain system with a closed cooling system?
It's what it sounds like, if so, those are air lines, not fuel lines.

Ah, I wasn't aware that they did that. But I was pretty sure they weren't going to be fuel lines.

If that's the case: Air Lines = Easy.

 

[Squire]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

I don't have a closed cooling system, only raw water. Now that I have looked at a photo of the front of my engine (boat is 2 hrs away) I realize that the thread I found on the Four Winns site via my google search that had a picture tutorial for removing the pump was on an identical engine except that it has the air actuated drain system. I believed that this 350 was raw water only as well because there was no front mounted coolant reservoir ala the 350 mag mpi horizon.

Thanks for your replies; I now expect to find a seawater pump without these connections - should make it easier to remove hoses from back of pump. (Easier is a relative term

 

[TilliamWe]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

...

Thanks for your replies; I now expect to find a seawater pump without these connections - should make it easier to remove hoses from back of pump. (Easier is a relative term

Exactly!

 

[Squire]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

Got the job done in about 2.5 hrs. The pump comes out with the bracket still attached - there is a little tab on the port side of the bracket that catches behind the main flywheel and can just be wiggled around it to drop the pump. I thought it may help hold the pump from moving forward while trying to attach the hoses at the back of the pump but the hoses are not quite long enough to reattach in this position. It still works better to have the pump dropped and pushed back to reattach the hoses.
My impeller was disintegrated and by detaching the hoses at the thermostat housing and back flushing with a garden hose I recovered what I believe to be about 80% of the impeller wings. I hope the rest of the pieces were small enough to flush right through the system and out the exhaust.
My job was made easier by removing the cooler bin and bulkhead forward of the motor well to provide about 2 ft of room in front of the motor. The job is extemely simple as there are very few parts to dismantle and reassemble but the fact that virtually every bolt/nut is a different size adds to the time. I would tackle this again but wouldn't expect to knock much time off the job.

 

[TilliamWe]

Re: Impeller Replacement on 2005 350 Mag MPI Bravo 1

Unfortunately, don't be surprised if those missing pieces are still in the system somewhere. They like to get stuck in the coolers (different setups have different ones) or in my case, in the thermostat housing. If it runs a little hotter than it did, but not overheating, check the thermostat housing for a chunk.