replacing water pump impeller

lukeb83

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Feb 19, 2012
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im looking to replace the impeller on my boat. i just got it and the guy i bought it from said it hasnt been replaced in 3 seasons. shes an 86 larson bow rider with the 3.0 mercruiser and alpha one outdrive. ive never done one before and i was wondering if this is a very difficult thing to do. also where is it located? and what kind of tools will be needed to get the job done right. thanks alot guys!
 

Don S

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Re: replacing water pump impeller

It's in the outdrive. You need to remove the drive from the boat (easiest way for a first timer) plus it lets you check some other things and lube the coupler splines, check alignment, check for water in the bellows and such.
The pump impeller is then replaces as shown in the link below .

http://forums.iboats.com/showthread.php?t=387864
 

lukeb83

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Re: replacing water pump impeller

thanks alot don. keep up the good work sir!!!
 

ziggy

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Re: replacing water pump impeller

You need to remove the drive from the boat (easiest way for a first timer)
imho, easiest way period. last time i dropped the lower only on my boat it must have taken me 80 tries to put the stupid thing back where i found it (with two people too). on the bench, i put it back where i found it in 1 or two tries (by myself)... + i get to do my needed pm to the rest of the drive while it's pulled.. i don't think i'll ever drop just a lower again for how painful it is to put back.. least that's how i feel about it.. with a home made drive stand, i pull and put my drive back on by myself too. granted, i gotta have help from my boy (22 year old) to move the drive from the basement to the boat or visa versa.. i just ain't as strong as i used to be i guess.. older age setting in... :(
 

lukeb83

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Feb 19, 2012
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Re: replacing water pump impeller

ok guys. thanks alot. im going to do just that. ziggy, by "putting it back where I found it", are you talking about the trim tab? where it says in that manual (dons link) "mark trim with tape"??? and don, can i get a link just like the one you provided except for pulling the drive?
 

achris

More fish than mountain goat
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May 19, 2004
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Re: replacing water pump impeller

.... last time i dropped the lower only on my boat it must have taken me 80 tries to put the stupid thing back where i found it (with two people too). .... :(

Girl! :D :D :D

Dropping just the gear housing is easy... Piece of cake. Try it on a OMC outboard and then tell me the Merc ones are hard!

Chris
(just messin' with ya :D :D)
 

dubs283

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Jul 27, 2005
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Re: replacing water pump impeller

he meant getting the lower half back mated with the upper half still attached to the boat

you are going to pull the whole drive, (upper and lower together), then split the drive halves on yur workbench to replace the water pump assy

as far as a link to pulling the drive i dont know if/where one is but before you even pick up a tool read the adults only or DIY'r section (they are the same) first, lots of info that pertains to what you will be doing and future maintenance tips too - there may be info on pulling the drive but if not:

1. put remote shifter at the helm in FWD gear

2. remove the trim ram pin at the rear connection

3. remove the six nuts at the bellhousing and pull the drive off
 

achris

More fish than mountain goat
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Re: replacing water pump impeller

ok guys. thanks alot. im going to do just that. ziggy, by "putting it back where I found it", are you talking about the trim tab? where it says in that manual (dons link) "mark trim with tape"??? and don, can i get a link just like the one you provided except for pulling the drive?

Here's a link to the GENUINE service manual -> http://www.4shared.com/document/zz_5pj9o/Service_Manual_06.html

You'll find all the info you need in there.

Removal of the drive is
1. Put controls in Forward gear.
2. Remove the trim ram AFT anchor pin nuts and remove the trim rams off the anchor pin. Leave the trim rams connected at the front (The ones nearest to the hull). Tie the trim rams up with a length of rope to stop them falling down as you pull the drive (It also makes it a lot easier to re-install the drive come the time).
3. Remove the 6 nuts holding the drive to the bell housing.
4. Pull the drive back. Support its weight and be ready, it's heavy! about 40kg heavy!

That's it! Shouldn't take any more than 6 minutes and 32 seconds...

Chris........
 

ziggy

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Re: replacing water pump impeller

he meant getting the lower half back mated with the upper half still attached to the boat
yep, that's what i meant. it's just a bummer to mate (lifting it stright up) the drive shaft splines, the shift shaft in the upper (that falls down out of the shift shaft in the bell housing w/o the lower attached) and the water tube and plastic guide. on the bench, ya can see them + maneuver them to mate. i use part of my flo torque II prop assy. to use a adj. wrench on to spin the drive shaft to mate the spines w/ the drive shaft in the upper. it's just plain easy on the bench. the trim tab is easy. as for putting it back where i found it. i just guess at the proper place. but i know about where i want it from past expereince of adj. it. a shade to starboard for me. if i don't like it there. i can adj. after i use it and find i don't like it where it is. easy adjustment.

:facepalm: coullldddd beeee... but my gf don't think so... ;) besides, i got the idea from here on iboats. where the facts are found... ;) i'll pass on the obsolete marine corp drives if at all possible thankyou (learned that on iboats too).. so far so good. i'm just shade tree ya know. don't need any extra problems of trying to maintain a boat...:D
 

ktbarrentine

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Re: replacing water pump impeller

I will vouch 100% for the comments in this thread! I am a new boat owner, too (1990 Mercruiser 5.0L w/Alpha-1). With no prior knowledge, but with the guidance of this forum (and the linked manuals) and basic shade tree auto mechanic skills, I tackled the job myself (well, ok, had the help of my dear first mate). Perfect results! Pay close attention to the instructions! No real "special tools" for this, but is good to have the right torque wrenches, and put together a pressure and vacuum tester for when you get it back together. And take your time. It is amazing how fast you will get help if you run into the least little issue and post it on this forum! Dont wing it. Good luck and get it in the water! (note... you may also find some "how to" videos on youtube for these drives. Some are better than others, Some I watched just for fun. Oh, and build yourself a nice work stand for the garage.
 

lukeb83

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Feb 19, 2012
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73
Re: replacing water pump impeller

just went to order the kit and wanted to make sure im going to order the right one. alpha 1 gen 2 correct?
 

ziggy

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Re: replacing water pump impeller

a '86 would be a alpha1, not alpha1 genII.
 

ktbarrentine

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Re: replacing water pump impeller

Your serial number on the drive will confirm the model and parts required. Several good sources to look at that, too. Personally, I've found www.crowleymarine.com to be very good at providing parts lists by model/year/etc. Good exploded drawings, too!. Also.... another thread I've been participating in for this vintage drive will advise you NOT to put the replacement O-ring on the top portion (under the splines area) of your vertical drive shaft when you put your halves back together (thanks, Achris!). You can also search the threads on how to put together a pressure tester and a vacuum tester. The threads have good pics and the components are readily available (hardware store, Amazon, etc). (PS... mine is a 1990 and it is an Alpha-1, gen1. I believe that is the last year of the gen1)
 

Don S

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Re: replacing water pump impeller

Year is not a good thing to go by, that is nothing more than the year of the boat. It's possible your boat has been repowered. If you can find the serial number for your engine and drive we can get you exactly what it is.Here is where you will find the numbers.
attachment.php
 

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ziggy

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Re: replacing water pump impeller

i'll stand corrected.
s/n is the way to id it.

does look like somethings up as there was no 3.0 mated to anything prior to '87... maybe it's a 85 w/1-mr? or as stated above. maybe a full transplant w/?

i just stand corrected.
 

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lukeb83

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Feb 19, 2012
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Re: replacing water pump impeller

it is an '87. my bad. ill get the s/n and find the parts i need that way. thanks guys.
 

lukeb83

Seaman
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Feb 19, 2012
Messages
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Re: replacing water pump impeller

i take that back its an '86 with the 140. whats the difference between this motor and the 3.0?
 

lukeb83

Seaman
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Feb 19, 2012
Messages
73
Re: replacing water pump impeller

i take that back its an '86 with the 140 hp. whats the difference between this motor and the 3.0? is it a good reliable package?
 

lukeb83

Seaman
Joined
Feb 19, 2012
Messages
73
Re: replacing water pump impeller

does this setup have the power i need to pull a tube or maybe a skiier?
 
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