Impeller Change on 2007 350 MAG MPI w/ Bravo 3

pet575 · **Posted:** Sun May 03, 2009 3:35 pm

OK, so I was griping the other day about buying a $30 impeller. Had plans to change it this weekend that got derailed. Probably better, though, as I got to wondering if I should've bought the "kit" v. the impeller by itself.

Anyone changed an impeller on this engine? From what I have heard, it is just an o-ring that serves as the gasket and it is a pretty quick job. Anyone have any pointers, suggestions, photos, etc. that might be helpful?

Can't imagine this is a difficult project, but some experienced info would be helpful.

Thanks!

LouC · **Posted:** Sun May 03, 2009 4:22 pm

Never had a Merc but I think if you go over to the I/O forum on http://www.iboats.com and look in the 'adults only' sticky, there may be a Merc manual with the info you need that you can download...
I just did my 88 Cobra impeller...easy job...I always do the whole thing, housing, impeller, wear plate, gasket..etc and keep the old impeller still in the housing as a spare..if need be I could change it with the boat on the water by tilting the lower unit all the way up. It's one of the maintenance jobs that is good to know how to do...

ht32bsx115 · **Joined:** Wed Nov 21, 2007 1:40 pm **Posts:** 278

It's a pretty easy job. Just a couple of hose clamps (note which hose goes where), a few bolts and you can swap it out pretty quickly.

You probably can get away with just changing the impeller and not the housing or plate, unless you ran it dry. (did you run it dry?)

If you did and you destroyed it you will probably need the kit.....AND if the pieces are not all there you'll also need to recover all the pieces from downstream which are probably crammed in your oil/PS cooler or "coolfuel" cooler.

If you need the kit you could get one like the following from EBASICPOWER:

I think I paid about $60 for the kit I got.

According to my 1997 Mercruiser owners manual it indicates: "the seawater pump should be disassembled and inspected anytime insufficient seawater flow is suspected (if operating temperature exceeds normal range)" It doesn't give a particular interval. My brother has a Ski boat with a Mercruiser Inboard 5.7L engine that also uses the BRAVO Pump. He bought the boat new in 2000 I think. He finally got around to changing the raw pump last summer. :shock:

Most suggest 2-3 years. (less in salt water) I just changed one in an Alpha GENII that was about 12 years old. It was fine but I changed it anyway...

If you didn't run it dry etc, why do you think you need to change it?

tennja · **Posted:** Mon May 04, 2009 8:24 am

pet,

Not a big deal to replace. The biggest issue I had on my cruiser was access. It was low in the engine compartment and not a lot of room in front of it. You should replace the O ring with the impeller. That was a bit tricky to get to stay in the groove as it has an irregular shape. I used a bit of soapy water to get the impeller into the housing. But all in all it took less time than I thought.

BrentC5Z · **Posted:** Mon May 04, 2009 8:39 am

I think when you actually start doing the repair you will realize how simple it is.

pet575 · **Posted:** Tue May 05, 2009 3:41 pm

Well, with everyone's input and a little research, I decided to go ahead and get the impeller kit with wear plates. I kept the single impeller part by itself as well (the $30 one I was griping about). The kit was $81 at my local parts dealer. Looks like I'll be shopping online for THAT little number from now on. :evil:

I'll see what it looks like when I crack it open, use the appropriate part(s), and return whatever one I don't use. I'll try to snap some decent pics for posting.

impulse · **Posted:** Tue May 05, 2009 5:38 pm

I know it's a different engine, but I tackled mine this year. Here are some of the pictures I posted and the discussion:
http://www.smwebhead.com/phpBB3/viewtopic.php?f=3&t=2881&st=0&sk=t&sd=a&start=75

impulse · **Posted:** Tue May 05, 2009 5:58 pm

Hey - one thing to ask all the guru's on here. How critical is it that you get all the impeller fins folded in the right direction/orientation? Once the thing starts to spin will they just fold the way their suppose to go (if that makes sense)? And I assume the big hose is inlet and small hose is out? I guess I could figure that out if I looked closer at the hose routing, but nowhere near the boat right now.

edit: I did add some impeller lube to each of the ends of the fins as well as to the inside of the impeller housing.

tennja · **Posted:** Tue May 05, 2009 7:20 pm

When I changed mine last year I tried very hard to make sure they were in the right direction. After several tries I forgot which was the right direction. I found that easily by hand turning the pulley wheel that I could get them to flip easily. So I figured the motor could do the same so I just put it in and had no problems.

impulse · **Posted:** Wed May 06, 2009 1:52 pm

tennja wrote:

When I changed mine last year I tried very hard to make sure they were in the right direction. After several tries I forgot which was the right direction. I found that easily by hand turning the pulley wheel that I could get them to flip easily. So I figured the motor could do the same so I just put it in and had no problems.

Ok, that's good to know. I had the dealer run it on the muffs while I had it in for warranty work a few weeks ago, but still haven't gotten it in the water yet. Really, really hoping this fri or sat if the weather holds out. I'll be keeping a close eye on the water temp guage for a bit.

www.iFourWinns.com

Impeller Change on 2007 350 MAG MPI w/ Bravo 3

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