Impeller change - stupid questions inside!

[Joehs]

Hey all,

I've searched and while I believe I have an understanding of this process, this is my first boat and I want to make sure I'm all squared before I order and start opening stuff up.

So, I have a 2004 21i with the Mercruiser 350 Mag, serial 0M3911xxx. I believe this is the correct part if I'm going to replace the impeller and o-ring, right?

Next set of questions: When I go to do this, since it's an inboard vs a V-Drive that the walkthrough here is written for, I shouldn't need to remove the whole assembly to replace the imepller, right? As I should have decent access to the whole assembly, I can just remove the two hoses (after marking them) and then take off the 5 cover bolts and pull the old impeller out? If I do it this way, do I still need to loosen the pulley as per the walkthrough or should I be able to do it without doing that?

Last, heard of people using some dish soap or something similar to get it to spin easier going into the housing, is this legit? I don't want to do anything that could harm the engine or cooling system but my gut says it's probably fine.

I'm hoping to have an impeller overnighted and swap it out before Saturday morning but I'm not sure how tough it might be to do it on my own without any previous experience.

Thanks for putting up with some questions I couldn't find straight answers for. I know this subject comes up a lot.

[Thegerman618]

Joehs, Yes that appears to be correct part.

The entire water pump assembly is held on to the motor/frame with 4 of the 5 bolts that keep the water pump cover in place with a nut and washer on the front of the frame. (kinda hard to explain but you will see when you get in there) Basically once you remove the nuts the pump will come off regardless and honestly take the pump off. You may be nervous about pulling the pump out completely, but trust me everyone is nervous the first time until they do it once and realize its actually really easy and makes life a lot easier when pulling the old impellor out. Sounds like you already did your homework on this but here was my steps on my old 350:
1. Remove Hoses, you can mark if you want.
2. Remove serpentine belt
3. Remove nuts on the front side of the frame (behind the pulley)
4. Remove water pump once the nuts and washers are off.
5. Remove 5 bolts, and wear Cover
6. Pull old impellor (if your going to apply soup now is a good time to help slide the old one out)
7. Remove o-ring off the housing and inspect the housing inside for burs or cracks
8. Little soap on the new impellor and install don't worry if you cant get all the blades to face in the same directions 1 turn of the motor will take care of that for you.
9. Drink a beer your almost done
10. From here just work everything backward to put it back together.

Tip on the serpentine belt, there is a roller and the tensioner as the top 2 rollers you want the belt tight enough that you can turn that belt 90 degrees or no more that 1/2" of lift or movement up and down on the belt.

[Joehs]

So I'll need to fully remove the serp belt, or can I just loosen the tensioner pulley to take enough off of it that it's okay to remove the water pump housing? Was hoping to avoid that step as I've never done the belt before and I'm a tad nervous about it. The rest of it I have a fairly high degree of confidence I can make happen. End of the day it's just 5 bolts and 2 hoses, from what I can tell. Now if the veins are all broken off the impeller then i'll need to hunt those down and it'll become something harder. Until I get in and see it though I won't know for sure.

I went ahead and ordered the part so I can have it, if nothing else.

[Thegerman618]

you wont have to take the entire serpentine belt off, but in order to remove the waterpump you will at least need to take the belt off the pulley.

IF the veins are broken off the impellor, there is a very good chance (depending on how bad the destruction was) they got caught in the trans cooler/heat exchanger catch. To inspect this here is the steps:

Top hose (small hose) or outlet side of the pump connects to a long cylinder with 2 line from the transmission going to it. Remove the small hose from in between and grab any debris inside.

Here is a horrible but relatively accurate idea of how it works.
Trans cooler.jpg

Sorry I don't have a 350 anymore or I would post more specific instructions.

[Thegerman618]

Do you have an Iphone by chance? if you do, and you want to give me a call on facetime and I can point out more specifically the parts I am referring to or need some help just let me know.

[Joehs]

Do you have an Iphone by chance? if you do, and you want to give me a call on facetime and I can point out more specifically the parts I am referring to or need some help just let me know.

I don't, but I appreciate everything you posted up! I think I can make it happen. Honestly, I'm probably over thinking it.

Is the pulley I adjust for tension the one directly above the water pump pulley?

[Thegerman618]

yep that's the one! Its a very easy change, first time take about an hour, and after that you will be able to this in 20min.

[Joehs]

Gave it a shot today. I don't think I'm meant to work on boats hah.got the belt loosened and both hoses off the housing but only managed 3/5 bolts. I'm not sure what sort of wizardry everyone else has thar can get up behind the housing without removing the fuel filter/pump but i dont have enough 90* socket bends hah!

I still think i could do it if i had more tools but i dont lie, i feel allittle defeated hah!

[lee]

Just unbolt the bracket from the engine with two bolts, then you take apart the impeller housing with ease.