Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

[tobra100]

Does anyone out there have any info or video on how to change a water pump on a 496cu.in bravo III with an enclosed cooling system? I sure could use any instructions. with the enclosed cooling system, you cant even see the pump.

Thanks Ray edit;

 

[Bondo]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

Ayuh,... Up in the Adults Only section are links to the factory manuals,....

Generally speakin', ya remove the entire raw water pump, rebuild it, then reinstall it,...

On yer motor, I believe it's way down low, starboard side, forward corner,....

Pay attention to which hose goes where, as they're the same size, 'n reversible, with disastrous results,...

 

[Speakrdude]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

+1 on the last sentence.....

 

[alldodge]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

Not knowing your engine serial number I will guess the below link will be the breakdown of your raw water pump. Also no need to get into the closed cooling part

http://www.mercruiserparts.com/Show...5.png&inbr=13832&bnbr=190&bdesc=Seawater+Pump

 

[tobra100]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

ok, how do I get into the adults only area? or how do I get to the factory manuals? Thanks guys

 

[OllieC]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

I hope you have long skinny wrists….. I hate changing mine…..Love/Hate that is…..

 

[BrianNJ]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

I ended up removing and installing mine three times this year. Practice helps. Mine is on a 350MAG engine. It should be about the same.
Like OllieC implied, it can be difficult to reach if you cannot access the from of your engine easily.

There are some good pictures and instructions that someone posted here: www.iFourWinns.com • View topic - How to change impeller in '07 Merc 350 MAG MPI w/ Bravo 3. I hope it is not bad manners to post from another forum...?

I did mine a little differently. I was about to remove the intake and output hoses from the back of the pump and remove the entire pump. There may be a quick disconnect on the intake hose about halfway between the tan some and pump that tulips provide some slack. The intake hose is pretty stiff to avoid collapse under vacuum. Mine is red like the one in the pictures. Intake goes on top, output on bottom.

Be sure to check for wear in the pump housing when changing. It is a common problem and lead to my three times through last summer. See thread and pictures here for more on that. http://forums.iboats.com/mercruiser...awater-pump-wont-draw-water-muffs-627400.html

Does this image of a 496 with closed cooling look like yours? If so, it shows belt routing and the pump is on the bottom left. Hopefully you don't need to remove the heat exchanger to get down there.

 

[alldodge]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

ok, how do I get into the adults only area? or how do I get to the factory manuals? Thanks guys

The adults only section is the first line in this section or click on the below link
http://forums.iboats.com/mercruiser...tdrives/adults-only-no-exceptions-288430.html

 

[OllieC]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

I did mine a little differently. I was about to remove the intake and output hoses from the back of the pump and remove the entire pump. There may be a quick disconnect on the intake hose about halfway between the tan some and pump that tulips provide some slack. The intake hose is pretty stiff to avoid collapse under vacuum. Mine is red like the one in the pictures. Intake goes on top, output on bottom.

Be sure to check for wear in the pump housing when changing. It is a common problem and lead to my three times through last summer. See thread and pictures here for more on that.

I'm not trying to hijack the thread, but I have the same setup. Red hose and black hose. I couldn't figure out the quick disconnects but it does look like an easier location.

As far as priming the pump. This was the same issue I had after I replaced my impeller last year. I had to hold the muffs in place to force the water into the motor, sucking in exhaust for 30 seconds. Once it filled, it was fine. However, before I figured that out, I was told I fried my impeller. So I removed it again and it was fine (vasoline)
I am going to read your link, because I imagine I will be going through this again this Spring with a drained block.

 

[Capt Ken]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

There is a clip you remove to separate the quick disconnect. Even when you remove the locking pin, you will need to get a screwdriver in there to separate the halves. But much easier than removing the hoses from the pump.

 

[BrianNJ]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

... much easier than removing the hoses from the pump.

In some cases, the quick disconnect just provides some slack. It may still be necessary to remove the hose clamp from the back of the pump. The bulkhead forward of the motor may be too close to turn the corner with that stiff hose attached.

WRT the comment OllieC made about Vasoline, I recommend it. It saved my impeller too and makes assembly easier.

 

[tobra100]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

Did your 350 mag have the enclosed cooling system, and the fuel filter assembly next to the water pump? Im still hoping that by the time spring rolls around, someone will be able to give more info on this. Thanks Ray

 

[BrianNJ]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

Did your 350 mag have the enclosed cooling system, and the fuel filter assembly next to the water pump? Im still hoping that by the time spring rolls around, someone will be able to give more info on this. Thanks Ray

I do not have enclosed cooling. However, the fuel filter assembly is next to the pump. I don't think either impacts the process. Neither should make a significant difference in the process.

 

[Fun Times]

Re: Impeller replace merc bravo III 496cu.in.375hp. ENCLOSED COOLING SYSTEM

Im still hoping that by the time spring rolls around, someone will be able to give more info on this. Thanks Ray

While there is not a lot of how to's with good photos online to do an 496 impeller, here are two that will help give you some ideas of what you're in for once your in there working on it. There are a few small write-ups if you do a google search of changing an mercruiser 496 impeller.

While this first link is the 350 mag small block and to me it seems like he went about it the harder way vs taking off the water pump bracket in order to work on the whole assembly on the workbench the design will be somewhat the same as you should have the Gen 3 cool fuel module like this guy does.
www.iFourWinns.com • View topic - How to change impeller in '07 Merc 350 MAG MPI w/ Bravo 3

Now the third link below is an 2003 8.1/496 with good photos and a good how to but since your boat is an 05, the design is now a bit different as you will not have the serpentine belt adjustment bolt to the port side like this guy does. Your adjustment design should now be done by a belt tensioner item number 24 in the second link. A bit easier then the bolt.

http://www.mercruiserparts.com/Show...9.png&inbr=11746&bnbr=210&bdesc=Seawater+Pump

How to Change Impellers in 8.1's with Pictures

Hope this starts to help get you heading in the right direction, good luck.

 

[tobra100]

Well guys, the boats out of storage, and within the next week I will finally be pulling the impeller. I wish that I had a movie camera so I could assist the next guy down the line. I will keep you posted. Thanks for all the help......I hope Ray