Keeper or Anchor

[aj4ct]

A friend gave me a 1975 model 200, 20 HP outboard serial # 4105975. during my inspection I found the ignition pick-up has vibrated loose and the top cover bolt also came loose, I did not mark, the flywheel prior to removal and would appriciate information, on how to set time. I do plan to purchase a manual when I complete inspection to verify if it's a keeper or an anchor.
73 Rodney AJ4CT

 

[8075mercury]

Re: Keeper or Anchor

These are super motors!

I would rotate the crank until the top cylinder is at top dead center and line up the flywheel timing mark with the top dead center mark on the pull start cover (assuming you have a manual start, I think the electric start has a timing marker too).

Wide open throttle is 33 degrees before top dead center. Throttle pickup (when the throttle pin first starts to move) is 3 to 7 degrees before top dead center.

In my mind, anchor decision starts with whether you have good compression, condition of lower unit and if you have good spark. Like you say a good service manual is invaluable.

Good luck!

 

[aj4ct]

Re: Keeper or Anchor

Thank you, for the information. I am trying to determine if the lower unit is locked up, or locked in forward/reverse. The engine will only turn 5 degrees either way, with spark plugs removed the pistons do move, when I try to turn by hand. Any advise on how to remove lower end would be appriciated "again a manual would be invaluable, once determined if it's a keeper.
Thanks again..

 

[8075mercury]

Re: Keeper or Anchor

Agree, I would say if it will not turn over, either the powerhead locked up or the lower unit is locked up.

A '75 20hp will start in forward or reverse so there is no lock out to only start in neutral.

To drop the lower unit, you need to remove the zinc plate in the bottom rear of the lower unit, to unscrew you need a long hex (or allen) key, can not remember the size, 3/16, 1/4? 5/16? and access through the hole (may have a plastic plug) in the top trailing edge of the mid section.
Next, remove the nut under the zinc plate, 2nd nut in rear of lower unit and nut on leading edge (stud is in the lower unit, nut sits in a notch at bottom of leading edge of mid section). You have to get the lower unit partially down to get this last nut completely off.
Sometimes, lower unit is stuck, of course, I usually tap with a rubber mallet on the bullet section of the lower unit, and inline with lower unit the leading edge and trailing edge. Prying and banging on the fins will usually break something. Hope this helps.

Good luck.

 

[aj4ct]

Re: Keeper or Anchor

Fantastic,
Just the information I needed, need to get ready for church this morning but will try this afternoon and post result.
73 Rodney AJ4CT


8075mercury and any other interested party,
After church this morning, a quick lunch, and a short prayer the lower end came off as stated "that allen wrench was 1/4" by the way", but maybe the man upstairs felt I should not be working on the engine on Sunday, because the lower end is not locked up. The shaft length is 17 3/4" from w/pump housing to tip of spline on the engine end.
A good part source, and a used "if possible" manual for a 1975 20 hp. model 200, serial # 4105975 would be nice about now, I've never gone thru an outboard engine before, but I was a certifed ASE Master Tech "Auto" but I hung up my wrenches in 1984 after lower back injury, as a civil service tech for the Department of Defence. All I do now is Emergency Communication "Amateur Radio" for the Southern Baptist Convention, and Navy-Marine MARS Radio Service, and of course a lot of fishing..
I'll check for comments later, and start tearing down this engine tomorrow with up to date findings, again I want to thank 8075mercury for your help.

73 Rodney AJ4CT NNN0UTG

 

[8075mercury]

Re: Keeper or Anchor

Glad to hear the lower unit came off ok.

Good luck on the tear down of the powerhead. Depending on the outcome, here is a thought, if you shop a bit, you might can find a replacement powerhead on ebay for a pretty reasonable price. I have bought a number off ebay with mostly very good success. A '73 to '76 would have the same ignition however, a 77 to 80 complete with trimmings would work also.

 

[aj4ct]

Re: Keeper or Anchor

Looks like we have a keeper, after carefull teardown and splitting the case halves things are looking good.

Will start new "thread" with findings, please visit "Lower rod/piston assy bearing damage"