'73 Mercruiser Water Pump Job

[ChampionShip]

I'm looking into changing out the lower unit water pump/impeller in my '73 Mercruiser 1-6 'boat-a-saurus' Cruisers. I was warned by a Mercruiser tech not to do the job myself because I would likely screw up the shift linkage.

Has anyone done a job like this successfully that could walk me thru the steps in detail?

What kinds of things do I look out for?

Where are the bolts to dismount the lower half of the unit? Hard to remove? What if I can't get the trim tab off to get to the hidden one?

Any help is greatly appreciated!

Thanks!,
Champ

 

[ChampionShip]

Re: '73 Mercruiser Water Pump Job

bump

 

[Don S]

Re: '73 Mercruiser Water Pump Job

There are hundreds here that have changed the raw water pump impeller them selves.
Go up to the adults only sticky at http://forums.iboats.com/showthread.php?t=288430 and download the OEM service manual to start with.
Then use the search feature of the forum. The subject has been discussed many, many times.

 

[ziggy]

Re: '73 Mercruiser Water Pump Job

I was warned by a Mercruiser tech not to do the job myself because I would likely screw up the shift linkage.

ya might, but it's undoable back to proper a second time and then ya won't make the error the 3rd time.

Has anyone done a job like this successfully that could walk me thru the steps in detail?

follow Don S' lead to the service manual. step by step instructions w/pics. if your unsure of the instructions, you can ask them here and folks will help ya out.

What kinds of things do I look out for?

two common mistakes i can think of are having the shift shafts out of time. that's what your mech. that wants your money is talking about. putting everything in fwd. prior to reassembly is the ticket to success (the remote at the helm and the lower unit when off the upper) also folks seem to forget to put the washer back on top of the lower shift shaft. might be more, but thems the ones i can think of off hand.

Where are the bolts to dismount the lower half of the unit? Hard to remove? What if I can't get the trim tab off to get to the hidden one?

5 of them are nuts and veiwable from the outside. one ft. 2 fwd of middle on top, 2 behind middle on the bottom and one cap screw (bolt) under the trim tab. 6 total. the s/m has pics if i remember right. if ya can't get the trim tab off, destroy it till it cooperates and replace it.

my take is do it yourself. use the oem s/m and iboats for support.

ya might consider removing the whole drive too. there is pm to do to the drive that is accessible only with the drive removed and the side benefit is the lower is MUCH EASIER to reinstall when on the bench than when lifting into place while the upper is still attached to the boat.

 

[ChampionShip]

Re: '73 Mercruiser Water Pump Job

I downloaded the manual, will have to take another look at the outdrive to match up the part #. So you're saying just leave the shifter in FWD at the helm, and then be sure it's in FWD when I put the lower back into place?

Thanks guys, I appreciate the help a ton!

-Champ

 

[ChampionShip]

Re: '73 Mercruiser Water Pump Job

Had the drive apart (top half on the boat) and replaced the impeller and housing.......now when trying to bolt the 2 halves back together there's about a 1" gap that I can't seem to get past. I tried using the old housing, tried leaving the water tube off, thinking it's that crazy shift linkage....... where do I go from here?

Thanks!

 

[BAproject]

Re: '73 Mercruiser Water Pump Job

did you put the drive in forward gear? and when you were messing around with it did you knock it out of forward gear? Put it back in gear and try again....you probably bumped it, same thing happened to me my first time!

 

[Bondo]

Re: '73 Mercruiser Water Pump Job

Ayuh,... If you're lackin' an Inch, I'd guess you're missing the alignment of the water tube, splines, or something else...
Are you holdin' pressure on the propshaft so it don't pop outa Forward,..??

 

[BAproject]

Re: '73 Mercruiser Water Pump Job

I would say it more likely pooped out of forward gear when you were working on it, very easy to do.....getting the splines to line up is much simpler and with the chamfer at the top of the splines it almost feeds itself in there with ease....

 

[ChampionShip]

Re: '73 Mercruiser Water Pump Job

Water tube was suspect when problem arose- tried aligning it without the water tube for comparison- same issue. Tried turning the shift collar (and yes, the boat is and was in fwd gear) trying to line it up, doesn't wanna go and I don't wanna bust it.

 

[Bondo]

Re: '73 Mercruiser Water Pump Job

Ayuh,... Have you turned the vertical shaft,+ retryed,..??

There's alotta things to align, All at once, but when ya Do, it falls inta place...

 

[Fishermark]

Re: '73 Mercruiser Water Pump Job

Turn the prop a little counter clockwise to move the splines a little.

 

[bigskiohio]

Re: '73 Mercruiser Water Pump Job

after the shift shaft engages you can turn the prop. alot easier on the bench. you start water tube and then shift shaft .

 

[ChampionShip]

Re: '73 Mercruiser Water Pump Job

....