1975 Johnson 15hp motor

[kjr80]

Re: 1975 Johnson 15hp motor

I think the kit vs impeller is more a remove and inspect deal although if you buy the kit you are replacing all the potential issues that can occur instead of just doing the impeller. Just doing the impeller is cheaper. Pull it apart and inspect. The pump grommet at the top can fold over, the bottom plate can wear, the inside of the pump housing can wear. If it all looks good from visual inspection why waste the money on an entire kit, that's my logic. IBOATS does sell the impeller by itself, Sierra p# 18-3050.

If my water pump is working properly should I even take the lower unit apart, it seems to be working fine and pumping out water, I just changed the gear oil, is there anything else that I should be looking at?
Thanks,
Kyle

 

[bktheking]

Re: 1975 Johnson 15hp motor

Your not taking to the lower unit apart, that's a whole other ball game, you are simply dropping the lower unit from the motor and inspecting the entire pump. 6 bolts at the bottom of the lower unit, shift into reverse, the motor will drop down so you can access the shift rod, take the bottom bolt all the way out of the shift coupler and with any luck the lower will come off. The pump sits under the housing at the top, 4 bolts to remove and slide housing up and inspect. I think if the question about the pump is coming up you should inspect it.

 

[OptsyEagle]

Re: 1975 Johnson 15hp motor

The problem you have is that this motor is not going to ring a bell for you when your impeller does fail. You will probably find out when the motor stops and the powerhead warps.

Since you don't know the current condition of the pump, if you change the impeller now, you know you will have a good one in there. Then I would schedule another change in at least 5 years (many here say 3 years and I will be wrong before they will).

Drop the lower unit. Inspect the condition of the impeller, housing and impeller plate. If the housing and impeller plate have no nicks or scratches, then just change the impeller. That is what I would do.

 

[Quacks]

Re: 1975 Johnson 15hp motor

you could convert your 75 to the later models with the "pee hole" I may do that after i figure out my water pump issue.
alittle past the middle part, "No overboard Water Indicator" section
http://www.sschapterpsa.com/ramblings/Johnson 9.9_15.htm

 

[bktheking]

Re: 1975 Johnson 15hp motor

What I did-

Bought the OMC fitting for the water jacket and lower cowl. 1/8 - 27 NPT tap and 11/32 drill bit and gasket for the water jacket. Drill the hole in the location of choice, tap it, thread tape and screw in the fitting. I ground down the fitting even with the jacket and a piece of tube to fit in between the 2 fittings.

 

[torbjorn]

Re: 1975 Johnson 15hp motor

I am working on a 1975 Johnson 15hp outboard motor and was wondering where the best site was in ordering new parts, is there a site above and beyond the rest for quality and availability? I also had the motor working last year, but I believe I have a water pump issue since I've seen rubber residue, I tried starting it today and it wouldn't even pop, which it has always at least popped in a few pulls. Where would be the best place to start first? I'm sure I'll have many more questions in the future and will need all the help I can get since my goal is to get this motor working before June and stay working.
Thanks,
Kyle

Seaway Marine in Seattle has a large parts stock, even for older OMC motors, and at lower than Bombardier prices. I just ordered all the parts I need for a 1964 Johnson 3 weedless, including steering and starter handles. There are other sources as well, but Seaway is fast and cheap.

 

[moonfish]

Re: 1975 Johnson 15hp motor

Never use starting fluid in a two stroke. Way bad for it.

 

[kjr80]

Re: 1975 Johnson 15hp motor

What would be the best way to start a stuborn motor, after I get it running it only takes one pull to start it, it's just stuborn when it sits for awhile.

 

[kjr80]

Re: 1975 Johnson 15hp motor

Should I try adjusting the fuel, maybe it's running too rich? I thought that maybe I should drain the gas tank and start with new fuel as well, but after I get it started with just alittle squirt of starter fluid it runs great, not sure what else to try here?

 

[bktheking]

Re: 1975 Johnson 15hp motor

Have you ever serviced the carb?

 

[cajuncook1]

Re: 1975 Johnson 15hp motor

Never use starting fluid in a two stroke. Way bad for it.

Use premix gas/oil ratio of 50:1 in a spray bottle, when spraying into carbs or sparkplug holes. Starter fluid has no lubrication and can potentially damage your motor. Also some starter fluids can damage/eat up plastic parts of the engine/carburetor.

Good luck with the motor, be patient, and your getting good advice from guys on this forum!!

cajuncook1

 

[kjr80]

Re: 1975 Johnson 15hp motor

Have you ever serviced the carb?

I've had the Carb cleaned and checked about 2 years ago, and 3 years before that I had a new one installed. Is there a Sea Foam spray that would help with the carb because once I get it started it will start all day with one pull, so the carb might just be gummed up? Thanks for all of the help, I wouldn't be able to resolve these issues on my own.

 

[bktheking]

Re: 1975 Johnson 15hp motor

Ok, well if you ran the gas out of it before the winter it might be clean. What is your starting procedure for the motor in question?

 

[OptsyEagle]

Re: 1975 Johnson 15hp motor

Did you try turning the carb adjustment knob a little counter-clockwise to enrich the mixture a little. The hard starting could be caused by a more lean mixture.

When you choke an engine, you are really enriching the gas mixture temporarily. A cold start requires a more rich mixture than a hot start. From what you describe (hard initial start, but Ok when warmed up), this could be the cause. Search for Joe Reeves method of adjustment for the carburetor.

Also, when you do start it, be careful how quickly you re-insert the choke. My 1975 9.9Hp likes the choke re-inserted a lot slower than my 1961 5.5Hp, for example. This last issue is kind of intuitive, so I would look at the carb adjustment first.