1975 Johnson 15hp motor

[kjr80]

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

 

[tashasdaddy]

Re: 1975 Johnson 15hp motor

right here http://forums.iboats.com/showthread.php?t=299680

check compression and spark. best place for parts and price and quick service, click Johnson parts on the top left of this page.

 

[kjr80]

Re: 1975 Johnson 15hp motor

Thanks for the info, another question I had was, should I be using a 50/1 mixture for this motor, I know some people use a different mixture depending on the motor and what they are using it for.
Thanks,
Kyle

 

[Wishiniwuzfishin]

Re: 1975 Johnson 15hp motor

Just ordered a part for mine from iBoats. Ordered on computer on Friday....got part in mail on Monday....using cheapest US mail service. Price for part and shipping was lower than anywhere else.

 

[tashasdaddy]

Re: 1975 Johnson 15hp motor

yes, 50:1 87 octane: TC-W3 outboard oil. synthetic TC-W3 oil smokes less, but much more expensive

 

[kjr80]

Re: 1975 Johnson 15hp motor

Just ordered a part for mine from iBoats. Ordered on computer on Friday....got part in mail on Monday....using cheapest US mail service. Price for part and shipping was lower than anywhere else.

Thanks for the info, how easy is this motor to work on, and have you ever had any trouble with getting parts for it. I ordered the repair manual yesterday.
Thanks,
Kyle

 

[tashasdaddy]

Re: 1975 Johnson 15hp motor

there may be 1 or 2 items NLA, but 99% are available, some things may be dealer only. they are a very simple motor to work on imho.

 

[bktheking]

Re: 1975 Johnson 15hp motor

On a scale of 1-10, 8, very simple design and pretty moduler to work on, my wife tore my 76 down to the transom clamps in an hour.

 

[JDusza]

Re: 1975 Johnson 15hp motor

I have a '79 Evinrude 15.
I have found BestBoatParts.com website very useful to view parts lists and exploded views, but, their prices are higher because they are BRP!
I have found iBoats prices to be better and the quality is (IMHO) the same. Parts are from Sierra instead of BRP, but, I'll bet they're made at the same factory and packaged differently.
Great engine. You'll enjoy it!
J

 

[OptsyEagle]

Re: 1975 Johnson 15hp motor

Where did you see rubber residue. Without pulling it apart I doubt you would ever see the impeller parts.

 

[kjr80]

Re: 1975 Johnson 15hp motor

When I started it last year I noticed rubber residue in the water of the barrel, little pieces, and it didn't seem to have the power that it once had?
Thanks for the info it's very helpful since I'm kinda new at all of this, but I have always wanted to learn to repair and fix boat motors.
Thanks,
Kyle

 

[OptsyEagle]

Re: 1975 Johnson 15hp motor

Well, you should change the impeller anyways since you don't know how long it has been since it was done and it probably needs replacing... and it's cheap. Unless the pieces were almost powder size, I doubt it is from the impeller, since it would have to travel up a water tube that can't be much more than 3/8" in diameter, through the engine cavities, past a thermostat and down out the exit holes that are also perhaps 3/8" in diameter.

 

[bktheking]

Re: 1975 Johnson 15hp motor

The rubber could have come from behind the prop, once fishing line gets behind it starts to grind up the bushing assembly.

 

[kjr80]

Re: 1975 Johnson 15hp motor

Just got my repair manual today, and it seems alittle confusing at first, but I'm sure that I'll get the hang of it. I really need to get this motor up and working before June, and I just hope everything goes smooth. Thanks everyone for the info and I'm sure that I will have many questions in the next few months.
Kyle

 

[kjr80]

Re: 1975 Johnson 15hp motor

Ok, I worked on my motor today and actually got it runnning. I noticed that the water was spraying out instead of a steady stream, I'm assuming that this is do to the water pump falling apart and plugging up somewhere down the line. I plan on replacing the water pump and impeller. Another question I had was, what kind of gear oil do I use for the lower unit? I have to drain the old oil out and I need to know what type I need? I also had a lot of oil residue in the water of the barrel after running it, what would cause that? Thanks for all of your help and hope to hear from someone soon.
Thanks,
Kyle

 

[bktheking]

Re: 1975 Johnson 15hp motor

Well the 75 15 doesn't have a tell tale like the later models, they had an exhaust hole at the top of the leg, if it sprayed water out the hole that's a good sign, no water, no pumping. I go to the OMC dealer and they give me OMC synthetic gear oil, that's the one I use, it's more expensive but it's good oil. You'll want to get yourself the pump too for filling. The oil is unburnt oil running out of the prop hub, perfectly normal, just make sure it's firing on both cylinders. All my outboards leave oil in the barrel.

 

[kjr80]

Re: 1975 Johnson 15hp motor

Thanks for the info, where would I find a water pump, I've looked on iboats and all they have is a water pump repair kit, is this what I need, or do I need to look somewhere else? I don't know if the water pump or impeller has been replaced in years, but it does seem to be firing both cylinders and like I said it does pump water, I just didn't know if it should be a nice stream of water or not?
Thanks, and I really appreciate all of your help,
Kyle

 

[bktheking]

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.

 

[OptsyEagle]

Re: 1975 Johnson 15hp motor

You will only get a spray from that motor. When you first fire it up, it takes about 10 seconds before the spray starts, since the T-stat must open before you get water out the hole at the top of the leg. Since this happens slowly, the spray starts slowly. As you run it you will see that the water goes from a spray to a drizzle and back to a spray again, as the T-stat opens and closes. That is normal.

 

[kjr80]

Re: 1975 Johnson 15hp motor

That's great news, I thought my water pump was shot, do you think that I should still look at the impeller, or do anything to the motor besides change the gear oil, grease, etc? I just changed the spark plugs, it wouldn't start until I added alittle starter fluid, now it starts first pull everytime. It needs routine maintenance, I just need to know what steps I need to follow.
Thanks,
Kyle