Mercruiser 330 impeller replacement

[Tommywalton1974 175]

This is how I changed my impeller on my 07 Avy walk through. Mercruiser 330 black scorpion. My boat was purchased in June of this year, 190 hrs. My experience with boats is NEVER leave your boat engine at risk of meltdown from a failed raw water impeller. The cost for exhaust hoses, head gaskets, cylinder heads or even a destroyed rotating assembly are to great compared to the impeller.

 

You cannot be lazy in this area. Change it or get it changed if you don't KNOW when it was last done.

 

If there is already instructions on replacement on the site just disregard this. Also if I left anything out feel free to correct me. I'm not a mercruiser mechanic.

 

Here goes. I first disconnected the 2 rams holding the engine hatch, swing it toward rear and prop it with something to keep from stressing hinges. They will stay hooked up.

 

My boat has sideswipe exhaust and the factory ballast tank is removed. My 1100lb fat sac now lives in this spot! I'm not sure if you can do it this way with the tank in place. It's easy to remove so just pull it out if its in the way. Then remove the grey piece that divides the engine compartment from the storage locker.

 

Now I removed my fuel water separator. 2 nuts, don't drop them or the spacers. Now you can see the pump.

 

Loosen serpentine belt idler on top, get the belt out of your way. Remember how it is arranged on the pulleys. My boat has a diagram on the coolant housing.

 

Now remove raw water pump inlet and outlet hose.

 

This is what I looked like in the boat, I'm big so this was fun..

 

Now there is one bolt and one nut on a stud holding the pump, 9/16" take those out and it's free.

 

Now disassemble the pump and put in the new impeller. Mine was ok but I just couldn't sleep wondering if it would fail. Use a new o-ring. Ill try to post a part number if its not already on this site. I used marine grease to lube it a little. Also a zip tie to compress it.

 

I greased my rudder shaft too while it was easy to get to.

 

Also major props to superdtf on the part numbers for the belt and idler pulleys I replaced all that too. My belt looked shot and both pulleys were sloppy.

 

Now just put it all back together. Total time 2 hours with pulley replacement.

[Bigcatpt 408]

Nice write up! Love the pic of you upside down.

[Tommywalton1974 175]

Thanks! I used my phone and a couple of pics need editing and ill add some part numbers!

[duramat 462]

Nice write up! Love the pic of you upside down.

X2!

 

Awesome!

 

I think the more how to threads of doing this the better. The odds increase of getting a good informative thread like yours.

 

Out of curiosity, how did your back plate look?

[Tommywalton1974 175]

It had some circular wear, nothing you could catch a finger nail on or really even feel. I'm guessing its normal. It appeared to be brass. So that's not much harder than the impeller! All looked fine.

 

The inside looked like the back piece

[superdtf 68]

Nice!

[AuT5 3]

Thanks for the advice, just changed my first impeller and only took about 30 minutes for the job. The direct drive configuration made it pretty easy. The only issue is that it is a 95 degrees outside so well over 100 in the shed. Time for a beer or three now .......

[Tommywalton1974 175]

95? Lucky, so lucky!

[AuT5 3]

After spending 6 weeks skiing in Japan, it was pretty tough coming back to these sort of temps. The area that I live generally has pretty mild summers so this was hot for us.

 

You guys in the US have been doing it pretty tough this winter - it has even made the news over here.

[enzo on LI 79]

Thanks tommy for this write up. I just changed my first impeller and it took about one hour. Same motor as Tommy's so his instructions were spot on. These DIY write ups are invaluable for everyone especially those of us a little unsure of how to go about it. Thanks again!!!

[ymanchu 1]

I'm going through the same process now as my '05 Avy is overheating. I got the fuel filter off but did not dive in there deep enough yet to find the attachment points for the pump assembly. Can anyone describe where they are? I still need to take off my belt, but my tensioning pulley looks like it just has a traveling gear on one side and the bolt on the other side. I didn't have my phone or camera on me when I was doing it, since I wanted to take a picture of where it was before I messed with it, and then storms washed out any further work plans. Did anyone ever post a part number for the impeller and O-ring? Thanks!

[Bigcatpt 408]

Release the tension on the tensioning pulley. Remove the belt and then just start feeling around in there for the bolts to the water pump. You just gotta dive in.

 

If you get the serial number off of your motor the shop should be able to find the correct impeller and O ring. But I am sure some here will already have that info for you.

[NW Boat Sports 232]

This part # can be cross referenced:

 

http://www.bakesonline.com/detail.aspx?ID=747

[MobEnzo 51]

Thanks for the write up! Just took care of mine for the first time. Took about 1.5 hours. This is my second season, but not sure it was ever changed previously. It had a little wear on it, so glad I did it!