1965 Johnson 75 HP water impeller

colsoncj

Seaman Apprentice
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May 28, 2005
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47
I changed the impeller on my 75HP, and have a couple questions.... when cranking the engine to start it, should the blow hole in the middle of the exhaust housing shoot water out? If not when cranking, how long does it have to run until it does?
 

Droll

Chief Petty Officer
Joined
Jul 30, 2003
Messages
514
Re: 1965 Johnson 75 HP water impeller

should the blow hole in the middle of the exhaust housing shoot water out?
You will have to crank the engine for a very looooong time :) .<br /><br />To test the impeller , start the engine in a barrel of water ( or in the lake/river/... ), fill it up till you are OVER the waterpump .<br />Start the engine , after some time ( 10 > 40 sec ) you will see water ( sputtering some water )coming out if the exhaust hole .<br />You shuld be able to hold you hand on the heads some secounds ( 3 > 5 Sec ) whitout getting burned .<br />When the thermostat opens > more water will come .<br />When the engine is at working temp See video ( save as ) of running engine 3.5 Mb .
 

colsoncj

Seaman Apprentice
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May 28, 2005
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47
Re: 1965 Johnson 75 HP water impeller

Exactly what I wanted to know! Thanks!
 

CATransplant

Admiral
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Feb 26, 2005
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Re: 1965 Johnson 75 HP water impeller

Nice video, Droll. That really answers the question, for sure. I like the boat, too.
 

colsoncj

Seaman Apprentice
Joined
May 28, 2005
Messages
47
Re: 1965 Johnson 75 HP water impeller

Droll, looks like your good with these motors... I have a 75HP with a set of sidedraft 90HP carbs on it. Do you know how to do all the fine tuning to get it running great? For example setting the dist to the carbs, adjusting fuel mixture, idle, timing? Thanks for the help man.... This is the first boat I've ever owned, and its been a lot of work, and I can see the light at the end of the tunnel, but im not quite there yet... gotta get this motor runnin good first.<br /><br />Heres some early pics of the restoration... the floor is done, transom is done, tops back on, wiring is done, seats are ready to go in and the motor does run, just not real well.<br /><br /> http://pk-designs.com/album.php?link=Friends/Cory/70 Duo Boat Resto/Set 2/&page=1&numpp=48
 

Droll

Chief Petty Officer
Joined
Jul 30, 2003
Messages
514
Re: 1965 Johnson 75 HP water impeller

looks like your good with these motors...
When you own one of this engines you need to know how to keep them running ;) <br /><br />The man to ask is Joe Reeves ,do a search on his name + some keywords ( carburator ?, timing ? ,adjustment ?,?? ) , he got some good tutorials on the subject .<br />You also might conceder buying a manual for your motor :) <br /><br />
I like the boat, too
I can only say thanks :) , was a project like the colsoncj is working on .<br /> More pictures
 

CATransplant

Admiral
Joined
Feb 26, 2005
Messages
6,319
Re: 1965 Johnson 75 HP water impeller

Cool! I've always lusted after a boat with fins. I'm on the lookout now for one to go with my RDS-20. The trihull is nice enough, but it sure would be fun to have a boat the same year as the outboard (1958), complete with fins.<br /><br />Painted to match the gold and cream colors on the engine, it would be a stunner, I think.<br /><br />Your boat is looking very nice. Is it finished now?
 

Droll

Chief Petty Officer
Joined
Jul 30, 2003
Messages
514
Re: 1965 Johnson 75 HP water impeller

Is it finished now?
When will an boat project be finished ?? ;) <br />Got some work to do this summer too , windsheld , new seat in the back ...
 

colsoncj

Seaman Apprentice
Joined
May 28, 2005
Messages
47
Re: 1965 Johnson 75 HP water impeller

That is a beautiful boat!! One day mine will be there, right now I'm on the super tight budget (still in college).
 

colsoncj

Seaman Apprentice
Joined
May 28, 2005
Messages
47
Re: 1965 Johnson 75 HP water impeller

I got the motor running great, but I'm only getting a sprinkle out of the blow hole... What kind of volume of water should this be putting out at a little above idle? <br /><br />Also, I'm still getting water in my lower unit... I've replaced the two seals below the impeller housing and the one about the impeller housing. I used silicon between the lower unit housings and between the lower unit and the exhaust tube. The impeller housing has two bolts sheared off.. would that cause it, or am I looking at a bad prop shaft seal? IF so, how hard is the prop shaft seal to change? <br /><br />Additionally, I've found out its a 100HP from around 1966... <br /><br />Thanks, Cory
 
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