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Author Topic: 1986 Johnson 70 Lower Unit Question  (Read 701 times)

January 23, 2013, 11:11:12 PM
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boykinjw

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1986 Johnson 70 Lower Unit Question
« on: January 23, 2013, 11:11:12 PM »
Guys, new to the forum but long time fan of Aquasports. I went to look at another 170 tonight that has the original 1986 Johnson 70 on it. When I pulled up the lower unit was off and the guy said it had started to make a rattling sound and the prop wasn't spinning so he had someone remove the lower unit to investigate. Long story short he doesn't want to spend anymore money on the boat so he is selling it cheap. I have a feeling he had it looked at and is playing dumb on whats really wrong, and I dont have the experience with lower units to know what Im getting myself into. The boat seams pretty solid otherwise, it has been used hard and there are some scrapes on the bottom from oyster beds(glass showing) and some cracks around the transom but I pulled on the motor hard and it didn't budge. I can pick up boat, motor, and trailer for under 1,000.00, should I even consider the motor as fixable or just start looking for a replacement? My plans for the boat would then to pressure wash the inside, sand the hull and prep, prime, and paint it.

January 23, 2013, 11:25:36 PM
Reply #1

wingtime

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #1 on: January 23, 2013, 11:25:36 PM »
Welcome aboard! I'd say your looking at a lower unit.  Does the boat come with it?  You'll need it for a core to swap it out for a overhauled unit.  Or you can see if SEI  http://www.sterndrive.cc/index.htm makes a after market lower unit for that motor.
1998 Explorer w/ Etec 250


1987 170 w/ Evinrude 90

January 24, 2013, 07:56:19 AM
Reply #2

fitz73222

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #2 on: January 24, 2013, 07:56:19 AM »
Before we throw the baby out with the bath water; make sure that this isn't just a spun propeller hub. Pull the propeller and see if the rubber hub looks chewed up are spun. I've heard spun propellers make all kinds of racket in the water under load. Since the lower unit is off, rotate the driveshaft by hand (clockwise) and push/pull the shift rod up and down and notice if there is any noise or clatter while shifting the lower unit through the three detents, foward, neutral and reverse. Also remove the gearcase drain screw and look at the gear oil for water and larger metal shavings on the magnet. Do these things and then we can talk about next steps.

Fitz
1973 Aquasport 22-2, twin 115 Mercs
2000 Baycraft 175 flats boat, 60 Bigfoot Merc
1968 Boston Whaler 13, 25 Yamaha (project)
1966 Orlando Clipper 13, 9.9 Merc

January 24, 2013, 09:43:33 AM
Reply #3

wingtime

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #3 on: January 24, 2013, 09:43:33 AM »
I should have said for the sake of buying the boat approach the sale with the mindset that the lower unit is shot.  Then base your offer and costs on getting it up and going on that position. Fitz is right that it might be a minor repair and if it is than that is a bonus to you!
1998 Explorer w/ Etec 250


1987 170 w/ Evinrude 90

January 24, 2013, 11:15:33 AM
Reply #4

flounderpounder225

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #4 on: January 24, 2013, 11:15:33 AM »
those 70 HP inline 3 cyl were bullet proof, one of the best motors OMC ever made, I had one go 27 years before it threw a rod.
Marc
1997 245 Osprey, 250 HPDI.  SOLD

January 24, 2013, 11:58:18 AM
Reply #5

boykinjw

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #5 on: January 24, 2013, 11:58:18 AM »
Thanks for the support!

The old lower unit comes with the boat so I'll take a look at the hub. Any recommendations on where to pick up a replacement? Ill try the classifieds here and probably THT, have you guys had much luck with ebay parts? Doesn't look like SEI carries them for the 3 cylinders, any reputable reman companies?

January 31, 2013, 11:03:58 PM
Reply #6

pigbike

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #6 on: January 31, 2013, 11:03:58 PM »
Most any propeller shop can rehub a prop. That is a common fix. Usually any other defects like chips and bent blades can be addressed at the same time. Check for a propeller rebuilding shop in your area, and ask for a estimate.

February 01, 2013, 11:13:01 AM
Reply #7

dburr

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #7 on: February 01, 2013, 11:13:01 AM »
Quote from: "fitz73222"

Since the lower unit is off, rotate the driveshaft by hand (clockwise) and push/pull the shift rod up and down and notice if there is any noise or clatter while shifting the lower unit through the three detents, foward, neutral and reverse.

Fitz

Farley does he have to worry about yanking the shift rod off the end of the shaft? :scratch:   I somehow over rotated :shock:  the one on my '98 70 Merc and spun it past reverse off the shift cam... That led to opening the lower unit and that cost some $$ in new parts but it was a good learning experience..
Dave

88 222 Osprey
00 Yamaha OX66 150
CAS # 2590

February 01, 2013, 01:06:45 PM
Reply #8

fitz73222

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #8 on: February 01, 2013, 01:06:45 PM »
Quote from: "dburr"
Quote from: "fitz73222"

Since the lower unit is off, rotate the driveshaft by hand (clockwise) and push/pull the shift rod up and down and notice if there is any noise or clatter while shifting the lower unit through the three detents, foward, neutral and reverse.

Fitz

Farley does he have to worry about yanking the shift rod off the end of the shaft? :scratch:   I somehow over rotated :shock:  the one on my '98 70 Merc and spun it past reverse off the shift cam... That led to opening the lower unit and that cost some $$ in new parts but it was a good learning experience..

OMC's had the shift rod threaded into a fulcrum that push or pulled against the spring and cross pin to move the clutch dog so you cant yank it out. But I share your pain about pulling the shift rod out of the cam on a Merc. Unless you are the luckiest SOB to get it back in you had to disassemble the gearcase to get the shiftshaft spline back into the cam. I've only done it once and that was enough!
1973 Aquasport 22-2, twin 115 Mercs
2000 Baycraft 175 flats boat, 60 Bigfoot Merc
1968 Boston Whaler 13, 25 Yamaha (project)
1966 Orlando Clipper 13, 9.9 Merc

February 02, 2013, 04:25:46 PM
Reply #9

dburr

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Re: 1986 Johnson 70 Lower Unit Question
« Reply #9 on: February 02, 2013, 04:25:46 PM »
Quote from: "fitz73222"

 Unless you are the luckiest SOB to get it back in you had to disassemble the gearcase to get the shiftshaft spline back into the cam. I've only done it once and that was enough!

Nice to know OMC got it right!!


And no, I wasn't lucky, it was the same day I bought lottery tickets  :mrgreen: :shock:  :shock:

I was guided by the Seloc manual..  Without the $OMG.expensive Merc tool and going by the "recommended method" with the little voice whispering in my head "don"t beat on that you know it's gonna break" I ended up having to replace the bearing carrier as well.. The beverage fund for the next month got wiped out that day :(
Dave

88 222 Osprey
00 Yamaha OX66 150
CAS # 2590

 


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