How to change out sea water pump impeller

[Jdwilli]

I have a 2014 5.7 MAG 350 Bravo Mercruiser. I want to change out the sea water impeller for the first time (I am an amateur mechanic). Getting access from the side bottom seems almost impossible. Access from the front bottom also seems challenging. Has someone done this job and how did they do it? Thanks in advance for your time

 

[Bt Doctur]

find the room/angle of attack, flexability of hands/knees/ elbows remove inlet hoses and plug with dowels or rags.Remove belt, Remove 2 mounting bolts, remove pump body, remove backplate bolts and nuts, R/R impeller ans reverse assembly

 

[Bt Doctur]

 

[Bondo]

I have a 2014 5.7 MAG 350 Bravo Mercruiser. I want to change out the sea water impeller for the first time (I am an amateur mechanic). Getting access from the side bottom seems almost impossible. Access from the front bottom also seems challenging. Has someone done this job and how did they do it? Thanks in advance for your time

Ayuh,...... Welcome Aboard, 'n to the wonderful world of wrenchin' on boat motors,......

BD has lain out the basics for ya,......

As to gettin' to whatever ya wanta fix,... it involves removing as much "boat", 'n other parts of the motor as necessary, to get yer fingers on what ya gotta get too,......

Some boats require pullin' the whole motor, just to change the spark plugs,.....

Hopefully yer boat won't be that extreme,.....

Btw,...... bein' double-jointed, 'n as skinny as a rail, is a Big Plus for boat Mechanics,.....

 

[tpenfield]

Yes, what ever it takes on a car for a certain task, I usually factor up 3X for the boat. Changing those sea water pump impellers is on the list of least favorite things to do. As stated, you will have to find the best access that you have to the pump. It won't be ideal . . . not by a long shot.

Make sure you mark the hoses before you take them off, else you'll be back posting as to which hose goes where . . .

 

[Jdwilli]

Is removal of inlet hoses absolutely mandatory, looks difficult, can’t even see one of them

 

[achris]

Is removal of inlet hoses absolutely mandatory, looks difficult, can’t even see one of them

Yeah, just a bit.

You could disconnect them at the 'other end' and pull the pump out with a couple of hoses attached, but getting them back into the right place would probably prove even more difficult.

Chris.......

 

[tpenfield]

If you are going to do your own wrenching on the engine, you will have to get used to performing the impossible

 

[muc]

Sometimes removing the cool fuel 3 module will help with access.
Sometimes I leave the hoses on until I have dropped the pump.
In most cases its best to remove the pump mounting bracket from the engine before removing the pump from the bracket.

 

[rickasbury]

One of the things I'm seasoned on and doing myself today. You did not mention why your doing this? Is it over heating? These brass bumps will wear and groove where the flat surfaces of the impeller turn. I fought this when I first got the boat- was surprised how little scouring will cause it not to pull water. These pumps are crazy expensive (700) and I found a kit where you put in a shorter impeller and SS steel wear plates. I boat in FL and the sand really does a number on them...if yours is scoured I would recommend doing this for 100, replacement impellers are 50...on the way to get my boat and replace right now myself...first time is the worst..if your closed cooling- you will want to make sure no pieces have broken off and gone into the heat exchanger ....

 

[rickasbury]

Also, I do pull the one line off the strainer and the other from the pump...also, when you go to pull the pump there is an aligning tab so you have to force the pump to the left to clear the tab while pulling. Put some grease on the inside of the houses you pull off for making it easier next time.

 

[Jdwilli]

I am only doing this because it has never been done on this boat, and I thought I saw that this was recommended every year. Boat is only used on a lake so shouldn’t be a lot of sand or sediment. Max temperature has not changed over the years, only gets to 180 or so. So question is, if the engine does not show any overheating, should I change it out?

 

[tpenfield]

Yes, change it . . . every 100 hours or so. Because when it fails, it is going to happen quickly.

 

[Bondo]

Yes, change it . . . every 100 hours or so. Because when it fails, it is going to happen quickly.

Ayuh,..... 'n it's many, Many times more work, 'n money to repair the damage caused at that point,......

 

[scoflaw]

Your a glutton for punishment if you change it every 100 hours. It's a very rugged pc.

I do 3 years or 300 hours and it looks fine when I pull it

 

[thumpar]

Your a glutton for punishment if you change it every 100 hours. It's a very rugged pc.

I do 3 years or 300 hours and it looks fine when I pull it

Once you have one go on you while heading out for a long planned trip you don't feel it is too much punishment to replace it more often. I even carry an extra with me. I'll spend the 45 minutes to change it over the tow of shame on a beautiful day.

 

[scoflaw]

Once you have one go on you while heading out for a long planned trip you don't feel it is too much punishment to replace it more often. I even carry an extra with me. I'll spend the 45 minutes to change it over the tow of shame on a beautiful day.

If you can RnR it in 45 min. your bilge looks way different than mine.

 

[rickasbury]

Imo I think it would matter also the water your in but agree 100 hours vs overheating when your hauling butt down the waterway can't end well...it really is no that bad once you've done it...I have a
motor with a 9' beam so I may have more room to work than most. If I did not have a generator sitting in front of the motor it would be way easier....

 

[thumpar]

If you can RnR it in 45 min. your bilge looks way different than mine.

Just practice. First time took about a day because I removed parts of the boat to be able to see it all. Now I know where the nuts and bolts are and don't need to look.

 

[scoflaw]

Just practice. First time took about a day because I removed parts of the boat to be able to see it all. Now I know where the nuts and bolts are and don't need to look.

OP has a diff setup than yours, he has the gen 7 brass pump, probably with the air lines and also has the CF3 in his way Same setup as my last boat that had twins and a genny. Not going to happen in 45 min.