Topic: 1982 Mercury 7.5 hp Impeller job HELP! – Antique Outboard Motor Club,Inc

This topic has 8 replies, 4 voices, and was last updated 2 years, 2 months ago by Buccaneer.

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October 24, 2022 at 6:12 pm #268199
Buccaneer
Participant
US Member
My friend brought his Merc back so I could install a new impeller.
The lower unit dropped off no problem. I struggled getting the
new impeller in the liner, but managed.

The biggest problem now, is I can’t get the gear case back
on all the way…… it’s shy of 5/8″ or so from glory.
The shift lever is in forward, the gear case is in forward,
and looking up the shifter rod hole, it looks like the funky
splines would be lined up.
When I move the shifter lever, the shift rod on the gear case
rotates. When I put the motor in neutral and pull the motor
over, the prop shaft rotates.

When I “rock” things around, my guess would be that it’s
the shifter rod not going into the drive socket.
The water pump discharge has a long pilot tube to start
over the water line and I can’t see that hanging up.

I tried first while the motor was on the stand, and then went
to “upside down” mode on the work bench, to no avail.

Any suggestions???? Thanks.

I can see why the Merc only pumped water when revved up.
One vane was bent backward, and all are hard set.

Prepare to be boarded!
October 24, 2022 at 6:54 pm #268216
dave-bernard
Participant
US Member
call me 1 914 310 7086 Dave.
October 24, 2022 at 8:59 pm #268222
Buccaneer
Participant
US Member
dave-bernard wrote:

call me 1 914 310 7086 Dave.

I watched a few Youtube videos tonight. Some guys tear them apart in “Neutral”
instead of Forward gear like I did. Not sure it matters as long as both pieces
are in the same selection. However, you can’t pull this Merc over if the gear shift
is in gear, so it would make more sense to do it in Neutral, incase one needs
to pull the engine over to get the driveshaft engaged.
I have a couple of things to try in the morning, then if that don’t work, I’ll call. Thanks!

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October 24, 2022 at 11:19 pm #268237
dave-bernard
Participant
US Member
use a long thin screwdriver to help guide the upper shaft into place by the lower rubber mount. I always do it in forward. on a stand.
- This reply was modified 2 years, 2 months ago by dave-bernard.
October 25, 2022 at 5:55 am #268241
billw
Participant
US Member
Not to rock the boat but when I have trouble, neutral sometimes works better. It is a more definite position. In forward, the detent in the gear case is not so defined. Keep in mind that just because the upper and lower shift shafts turn, it doesn’t mean they’re engaged. Could just be friction between the coupling and the shaft.

Do not underestimate the water tube. I know it has the guide, but it can still hang up, and trust me, you do NOT want to bend the tube beyond what it’s supposed to be. Take the top off the pump and insert the top, guide and grommet on the water tube, just to make sure it slides easy. Also, make sure that it’s all lubed up with something….grease, soap, whatever.

Hey, that impeller looks pretty good compared to some. At least you don’t have to worry about where all the broken bits went!

Long live American manufacturing!
October 25, 2022 at 11:16 am #268250
Buccaneer
Participant
US Member
It took another 1/2 hour of finagling, but I finally
got the gear case bolted on.
I tried forward, and reverse to engage the shift
rod, but it was finally neutral that ended up working
for me.

Notes to Self:
If I were to do another Mercury (and I basically have the same
motor that my dad bought in 1973) I’d have a “loose”
gearcase shift rod, where one could test the engagement
and position of the receiver spline.
It’s about impossible for me to hold the flashlight,
and look down the shift shaft hole, and tell where
the “flat” is in the splined socket.
(I say look “down” the hole because I had the motor
upside down on the bench)

The driveshaft “touches base” before the shift rod shaft.
I wasn’t sure about this, but (when in neutral) I pulled
the engine over a tad and the gear case dropped down
another 1/4″ or so.
It then took a little wiggling of the shift lever to get the
gear case to home base.
I’m not sure why none of this work yesterday. 🙁

I’m now draining the gear case to put in fresh lube……
hopefully the Merc takes generic Marine gear lube,
as that’s all I have.

I hope the engine isn’t flooded from being upside down.
When uprighted, carbon soaked gas dripped out of
the exhaust around the prop shaft.
Thanks for the suggestions!

Prepare to be boarded!
October 25, 2022 at 11:36 am #268251
crosbyman
Participant
Canada Member - 2 Years
note to yourself… 🙂

a small video cable can sneek up the housing and will light up the shift and drive shaft receivers and can be retracted after both S&D shafts are engaged

Joining AOMCI has priviledges 🙂
October 25, 2022 at 1:41 pm #268254
Buccaneer
Participant
US Member
crosbyman wrote:

note to yourself… 🙂

a small video cable can sneek up the housing and will light up the shift and drive shaft receivers and can be retracted after both S&D shafts are engaged

Somehow, I just can’t picture how this works.

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October 25, 2022 at 1:47 pm #268255
Buccaneer
Participant
US Member
Seems to pump water okay now, even at low idle.
After the video I adjusted the carb low speed needle and got
rid of the “lean” miss.

Just to be sure the fuel pump was “okay”, I put the gas tank
down on a stool after the video, and ran it another 10 minutes
or so with no problems.

https://youtu.be/HQuj7IRV4Eg

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- This reply was modified 2 years, 2 months ago by Buccaneer.
- This reply was modified 2 years, 2 months ago by Buccaneer.
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1982 Mercury 7.5 hp Impeller job HELP!

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