# Help, with 1980 40hp Merc 2 stroke impeller?



## Doboy (Oct 13, 2008)

*I want to drop the lower unit & replace the water pump impeller. (asap, it use to shoot out 10',,, now under 2')
'I' have never done it to an outboard before.
I've been watching dozens of Youtube videos,,, trying to find just ONE instructional video that shows my year of motor.
I have a shop repair manual ON ORDER. (3-4 days)
I do not want to break anything while trying to drop the lower unit,,,, so any type of GUIDANCE or helpfull comments would be greatly appreciated.
THANKS*

*1980, SN 5662261* 
SOME internet parts suppliers say it's a 402? (Canada),, 
https://www.perfprotech.com/mercury-marine-parts-catalog/model/01/3260/402, 40 (2 CYL.)/5556230-up

https://www.perfprotech.com/mercury.../489/18?search=46-77177A3&sortpartnbr=77177A3




*other suppliers say it's NOT a 402.*

Ebay; (no pump housing included,)
https://www.ebay.com/itm/233172503586

*Water Pump Service Kit for Mercury Outboards 
EMP Part # 46-07002*
This is a replacement water pump service kit without the base or housing. This kit fits Mercury outboard motor applications 30 thru 70 hp _as_ _detailed in the application chart below_. Kit includes the impeller, wear plate, gaskets and o-rings needed to service your water pump. If your pump housing and base are in good condition this is a economical way to service the water pump.

Replaces Merc Part #: 47-89983T2, 47-89983Q1, 
Replaces Sierra Part #: 18-3207


* Application Guide
HP/Model* *Serial #* *Year*
30 JET 0C159200 thru 0G589999 1989-1997
35 (350) (2 CYL.) 1571114 thru 2874703 1963-1969
35 (2 CYL.) 6445653 & Up 1984-1989
40 (400) (2 CYL.) 2874704 thru 3336257 1970-1971
40 (402) (2 CYL.) 3336258 thru 4860102 1972-1977
* 40 (2 CYL.) 4860103 thru 6445653 1978-1983*
40 (4 CYL.) 0C159200 & Up 1989-Up
45 (4 CYL.) 5531630 & Up 1986-Up
50 (500) (4 CYL.) 1521914 thru 4357639 1963-1975
50 (4 CYL.) 4357640 & Up 1976-1985
50 (3 CYL.) 6428681 thru 0D000749 1984-1990
60 (3 CYL.) 6428681 thru 0D000749 1984-1990
65 (650) (3 CYL.) 3293184 thru 4571651 1972-1976
70 (3 CYL.) 4571652 thru 6428680 1977-1983


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## bustedrod (May 13, 2015)

its fairly easy , but i recommend putting in a complete kit w/ base , replace the whole thing. put motor in n loosen the lower unit bolts untill ready to drop , seperate the L U before removing nuts completely so it doesnt fall . you can do this in up position. when you drop the unit dont loose any parts up inside the engine housing. slide it straight out holding on to the shaft. i usually remove the prop .. change pump make sure to lube the new impeller and twist into housing the correct direction. change lower unit oil when done just because.


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## Doboy (Oct 13, 2008)

THANK YOU, VERY MUCH,, for the reply.

Gives me confidence,,,,,,,,
UNLIKE all of the Youtube videos I watched, my shift linkage & pee tube doesn't seem to come apart up-top???
I will give it a try,,,, Now ;>)

This complete kit says that the 'bottom pump housing' is no longer available!?
https://www.ebay.com/itm/Water-Pump...KsAAOSwB3Zcmpjk:sc:USPSFirstClass!44442!US!-1

I'll know a bunch more when I get it apart.
Thanks


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## bustedrod (May 13, 2015)

you will be ok put it back together like it came apart, its just a gear box lol once you do it you will be amazed ....


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## dwmikemx (Mar 22, 2008)

I would suggest putting shifter in forward position before dropping the lower unit. Makes it much easier to re-install lower unit as you will need to align the drive shaft splines. And when in gear you can just turn the prop sightly which will rotate the drive shaft. 

If in "neutral" when re installing, you will have to turn flywheel in order to get spline alignment.


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## firemanmike2127 (Mar 17, 2013)

dwmikemx, I'm going to disagree with your method based on my experience & here's why. When you rotate the prop shaft to align the driveshaft splines you can cause the driveshaft & the NEW IMPELLER to spin in a counterclockwise direction which is exactly what you do not want happen. I'll refer to my 'clockwise rule' here in regards to impeller/lower unit installation. It is a much better idea to rotate the flywheel in a clockwise direction (as viewed from the top/looking down) whenever you are installing a gearcase to avoid the possibility of spinning the impeller backwards. If you accidently 'flip' one of the vanes the pump will lose a significant portion of water volume & can cause a damaging overheat condition. That's why rotating the flywheel in a clockwise direction to align the driveshaft splines is my preferred method. Additionally, I always remove the prop prior to removal/reinstallation because if you inadvertantly bump the prop you will also rotate the shift shaft, which can cause indexing problems when you are doing the reinstallation. Mike


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## bustedrod (May 13, 2015)

keep looking for a complete pump, there is alot of places to get parts and somebody has them, i have an old 86 merc tower and i run into that alot. but i seem to find parts. it takes a bit of searching ..once you do that pump you will be suprised how simple it is...


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## Doboy (Oct 13, 2008)

bustedrod said:


> keep looking for a complete pump, there is alot of places to get parts and somebody has them, i have an old 86 merc tower and i run into that alot. but i seem to find parts. it takes a bit of searching ..once you do that pump you will be suprised how simple it is...


Thanks.
I did find both pump housing pieces, with the complete kit on Ebay; (no upper shaft seal for splines)
https://www.ebay.com/itm/Water-Pump...-40-45-50-60-65-70-Hp-46-77177A3/332746175217

I STILL can't pry out the bottom half of the pump housing?????
I'm prying up, & tapping it every way imaginable, but I still can't get it to budge,,, YET.
There's 2 mounting PINS/ holes in it, that I might be able to screw a self tapping bolt into,,,, That'll make something to yank on,,,, or make some sort of 'PULLER'.

Here's some pictures;









You can see the 'melted' looking plastic in this pic. The housing wasn't aligned very well,,, from the factory.









ALMOST 40 years on this impeller,,,,,,,, that considered,,, it's not all that bad! ;>)
Last fall,,, it was STILL shooting water 10'!

















I had to cut the 'pee' tube off of the barbed fitting,,,, it was hard as rock. So I might as well replace the whole thing,,, up to the cowling. I'll get some 1/4" id 400* clear water/ gas/ oil line for that.?
So far,,, nobody has that part listed.


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## firemanmike2127 (Mar 17, 2013)

I generally use a large pair of Channellock pliers to remove the W/P base. Grasp the front & rear portions of the housing firmly & rock the pliers in a fore & aft motion while lifting in an upward direction. This technique has proven to be much quicker & more effective than trying to pry the base loose for me. Mike


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## bustedrod (May 13, 2015)

hey doboy that rascal is toast lol but it looks like ya got it. that splined shift shaft will pull straight up and out so watch , i had water showing up in my lower unit last year and when i pressure checked it the bushing was leaking. easy change.. and to keep the key from falling just wipe some grease or oil on it so it will stick. now the speedo tube on mine was ancient so i capped it off , i use my g p s for speed. try to use a 1/4 torque wrench to tighten the bolts down so not to warp the housing. glad ya got the whole kit, you will see why when ya get the old base out theres seals under it . your old impeller looks like when a motor run without water, also check the tube ,discharge tube for any stuck impeller pieces. dont worry about spinning the shaft accidentally it doesnt matter. when i get the pump snugged down with my fingers i like to spin the shaft and wiggle a bit so i can feel the pump alignment, just dont spin wrong way......its tight ... i try and tell guys dont even crank a motor without water on pump. you got it now and the pic is the oil fill screw seals that work good for me .


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## taterhead (Feb 10, 2018)

firemanmike2127 said:


> I generally use a large pair of Channellock pliers to remove the W/P base. Grasp the front & rear portions of the housing firmly & rock the pliers in a fore & aft motion while lifting in an upward direction. This technique has proven to be much quicker & more effective than trying to pry the base loose for me. Mike


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## Doboy (Oct 13, 2008)

Bustedrod,,, THANKS!

OMG,,,,,,,, I went brain dead! I spent 10 min trying to figure out how the pump's pressurized water
got over to that barbed fitting!!!!! OMG again! :<(
(OLD-timers! & 'getting older' every day!)
Did you take out the barbed fitting,,, or just plug/ cap it?



"i had water showing up in my lower unit last year and when i pressure checked it, *the bushing was leaking*. easy change"

BUSHING????? What one are you referring too?

& Would you happen to know those pump housing, tightening torque numbers? (just in case, the manual that I ordered might take forever to get here! AND I hope the numbers are in there!)


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## bustedrod (May 13, 2015)

the bushing on the splined shift shaft , it unscrews , uses a tool that i made looks like a deep well socket with lugs on end that way the shaft sticks up the middle and a wrench works the tool, so you dont have to pull the shift shaft out to change the bushing, and i just sealed the tube at the barb with my torch and needle nose .. i gont remember the torx inch lbs but i looked mine up on line in some old merc forums. but find snug tight and make them all the same works good, dont over tighten. i think 20 inch lbs on 7/16 bolt


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## $diesel$ (Aug 3, 2018)

Seems to me, (memory failing me) i had to uncouple a few things in the upper engine compartment when i changed mine last year? Not sure, either way, i've got a lot of 1/4" tubing. If you need it, bro, PM me and i'll send it to you.


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## Doboy (Oct 13, 2008)

OK diesel,,,, Mike & rod,,,, hopefully, the great feedback will help me, & others!?
(way Better than all of those Youtube videos! ;>)

PARTS, are in the mail. 'Be here Tomorrow'. I'll letcha know how it goes.
Big 2-day rain coming anyway,,,,, so i won't feel TOO bad working on it, in the garage,,,,,,,,,,,,,,


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## Doboy (Oct 13, 2008)

Hey diesel,,,,,,,,,, for some reason I can't send you a PM.?


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## $diesel$ (Aug 3, 2018)

No idea, Doboy. I got 2 just now from another member?


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## Doboy (Oct 13, 2008)

????????????????
I can click on 'bustedrod',,,, his box pops up & so does 'start a conversation'.
That command doesn't show up in your box for me. (lol,,, Ooooo that sounds suggestive!)

:<( ,,,,, LIKE, YOUR my only Y-town neighbor, & you have me 'LOCKED-OUT'!???? :<( lmbo,,,,,, 

I'll try it another way,,,,,,,,,


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## Lewzer (Apr 5, 2004)

$diesel$ doesn't have "start a conversation" option in his profile. I tried that last month and couldn't send him one. I had an old PM with him and just used that. I think the settings in his profile somehow changed.


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## Doboy (Oct 13, 2008)

Lewzer said:


> $diesel$ doesn't have "start a conversation" option in his profile. I tried that last month and couldn't send him one. I had an old PM with him and just used that.* I think the settings in his profile somehow changed*.



Thank You Lewzer,,,,,,, i tried 3 different ways to throw him a PM,,,, & NO GO.

$diesel$,,, Please send ME a PM, then maybe it'll work!?

The parts came,,,, & I managed to get the bottom 1/2 out after one hell of a fight,,,,,
like it was welded in there!
I'll post some more pics tomorrow am. Need to know info.


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## Doboy (Oct 13, 2008)

OK,,,, if someone else needs to do this job, these pics might help.

Here's the only way I found to get the bottom housing out. I drilled the alignment 'pin' holes out
deeper, with a slightly smaller diameter bit, then screwed in 2- 3/16" screws with a 'pry' nut 1/2 way up. (put a rag under the pry bars)









Here's the bottom 1/2 out; It was SO tight, I was almost off the floor trying to prying straight up. i couldn't budge it with pliers.









There were chunks of corrosion that fell down into the drive shaft bearing. I had to place the unit on it's side & squirt out the chunks with a spray bottle of WD40. I'm sure that the lower unit will have to be flushed 2-3 times before all of the crap is removed.
Now, with this pic, you can see how important it is to keep the bottom unit oil, filled TO THE TOP.
The OIL CHECK HOLE is even with the top of the bearing!


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## firemanmike2127 (Mar 17, 2013)

Doboy, I like the removal method you devised.....I've never tried using the dowel pin holes before. I do a lot of Mercruiser/Mercury O/B work & have had great results using the large (>4" jaw opening) Channellock pliers. If I come across a lower W/P housing that I can't remove by my traditional method I can use both methods simultaneously when an extra pair of hands is around. Nice work ! Mike


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## $diesel$ (Aug 3, 2018)

Yup, good idea, Mike. You got it by the glutious maxus now, my friend. Cake walk from there. Don't forget to put the impeler on the way your shaft rotates and clean out the tell tell hole.


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## bustedrod (May 13, 2015)

sweet you have the hard part done now. i have a slide hammer with a big screw on the end,, lube all the gaskets and o rings , now you can see why ya need a base ? good job....


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## Doboy (Oct 13, 2008)

bustedrod said:


> sweet you have the hard part done now. i have a slide hammer with a big screw on the end,, lube all the gaskets and o rings , *now you can see why ya need a base ?* good job....



Ya,,,, after this deal, I would never let any of my friends change out just a 'PARTIAL KIT'. ;>)


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## firemanmike2127 (Mar 17, 2013)

What I choose to sell my customers really depends on how their old components look AND whether I have records to document how old any related seals might be. If there isn't any damage related to excessive heat or starting the engine w/o a water source a simple impeller kit might be all they really need. That being said, I stock impellers, impeller kits & also complete kits because that isn't always the case. If I'm doing annual service for one of my regulars (w/ documented service records) a fresh impeller every 3-5 years is a good service interval. Mike


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## fastwater (Apr 1, 2014)

^^^Agree!
If there's no visible sign of wear(grooves,pits,etc) in the lower housing and it's not burnt and badly disscolored from excessive heat, a partial kit may be all that's needed.


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## bobw06231 (Feb 6, 2014)

Doboy said:


> Ya,,,, after this deal, I would never let any of my friends change out just a 'PARTIAL KIT'. ;>)


https://www.used.forsale/40-hp-outboard


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