1975 Johnson 15 hp questions

[wylie catter]

Hey everybody. This is my first post. I finally took the time to join. I've come here for info many times and it's a incredible site.

I'm descently familiar with boats and motors. But my question is about the little 15 I just got. It came from a man who bought it new. He used it for several years and took excellent care of it. But it has been stored for over 25 years. I believe it was set up correctly for storage because all of the electrical connections were unhooked. And all of the gas was drained and the prop was loose and all of that stuff.

So I got it home. Changed the fuel lines, went through the carb and checked it, and it fired right up. But just a tiny bit of water mist was coming out of the hole on the back. So I only run it a few seconds. A couple of different times. I've read that this might be normal. Or it might have a thermastat. But I don't know. Hopefully one of yall can tell me. So I have a water pump ordered for it.

Also does this motor have points? And should I replace them before I trust it to get me back to the ramp? It is firing like crazy. (big blue spark) Even with the 25 year old plugs, before I changed them.

Another question on a different motor, does an 1982 Evinrude 115 have points?

Thanks for any info.

 

[Will Bark]

Re: 1975 Johnson 15 hp questions

Are you running on muffs or in a tub? If in a tub make sure that water level is above the level of the water pump. Running for just a few seconds may not have let it get warm enough to open the thermostat. Was it overheating; if not, then a fine mist out of the exhaust relief hole is normal. Replacing a 25 yr old pump is a good idea. Why replace points and condensors if you re getting a blue hot spark?

Your 82 Rude does not have points, it is a cd ignition.

 

[OptsyEagle]

Re: 1975 Johnson 15 hp questions

It takes about 15 to 20 seconds before you visually see a good spray of water out the exhaust hole on that model. As Will said, the T-stat needs to start to open before you get that good spray.

 

[wylie catter]

Re: 1975 Johnson 15 hp questions

Are you running on muffs or in a tub? If in a tub make sure that water level is above the level of the water pump. Running for just a few seconds may not have let it get warm enough to open the thermostat. Was it overheating; if not, then a fine mist out of the exhaust relief hole is normal. Replacing a 25 yr old pump is a good idea. Why replace points and condensors if you re getting a blue hot spark?

Your 82 Rude does not have points, it is a cd ignition.

I was running it in a barrel. And it didn't get hot to the touch. I probably ran it 15 seconds or so each time. I just didn't want to damage something in the event that there wasn't any water moving. But I did have the "fine mist". The mist got warm but the head didn't.

And on the points I just didn't know if they would be reliable because of the age.

 

[wylie catter]

Re: 1975 Johnson 15 hp questions

It takes about 15 to 20 seconds before you visually see a good spray of water out the exhaust hole on that model. As Will said, the T-stat needs to start to open before you get that good spray.

Alright, so the spray should get noticably stronger when the thermostat opens.

I have another question I thought of. What is the correct setting for the air flow adjuster on the front of the carb. I barely had it running before, and will be able to do good adjustments when I get the new water pump in.

And thanks for the responces.

 

[jmendoza]

Re: 1975 Johnson 15 hp questions

Hello,
I have the same exact engine, and it need to be in a tank/trash can in order to see spray out the exhaust releif hole at the top of the mid section. Due to age, it is probably wise to replace the water pump impeller because it has been sitting for so long: the rubber blades have taken on a "set". I would also not be surprised if after a while you begin to have some issues with the fuel system parts that are rubber, like the fuel pump diaphragms, fuel lines, fuel disconnect fitting o rings, and squeeze bulb(primer) as the ethanol in todays fuel seems to attack them. I have replaced all of those pieces in mine after they were exposed to E-10 fuel, it took about two years for everything to fail, one by one!

Points are great, no problems with expensive and unreliable solid state ignition "power packs" failing on you in the middle of the lake. I advise you do check the timing with a light however, as if they are off just a little it can reduce power in this model significantly, gapping the points to .020" is not accurate enough to get both cylinders synched and firings 180 degreess apart, it's only a crude setting that ensures the engine will start and run.

See picture below of my 9.9 w/ 15 carb, identical to yours below:
It has run flawlessly for me since I aquirred it used in 1980. I recently put a new 1975 Evinrude power head on it, and re-sealed the gearcase, then re-painted the engine.

 

[wylie catter]

Re: 1975 Johnson 15 hp questions

I'm familiar with setting points on old trucks and stuff but I haven't even seen the points on this little motor yet. And I will defenetly need instructions on where to check the timing and how to adjust it.

I'm really appreciating all the advice. And I'm glad to hear somebody say "points are great". Because I was thinking that points were going to be a problem.

 

[jmendoza]

Re: 1975 Johnson 15 hp questions

The low speed mixture is set by putting the engine in forward gear, in a tank, or better yet, on the water, pushing the boat. With a warmed up engine, the mixture knob is slowly turned in until the engine begins to slow. It may speed up before that point however, but be sure to allow about 5 seconds before adjusting it any more for the engine to stabilze. Anyway, continue slowly turning it CW until the engine just slows or coughs, and back it out 1/4 turn CCW. Remove the knob, and replace it with the pointer facing straight up at 12 o:clock.

If you do replace the lower unit gear oil, get new washers for the drain and fill plugs, and be sure they are good and tight when replacing them, or they will leak. I used the BRP synthetic (OMC became BRP) gear oil and bought the little pump they sell for it as it's $5.00 and makes filling really easy.

Go to this link for more information on your engine, http://www.sschapterpsa.com/ramblings/Lower_unit.htm but one word of caution
should you decide to purchase the water pump kit instead of just the impeller:
DONOT USE THE LARGE LOWER WATER TUBE GROMMET, IT IS FOR LATER MODELS(1977 and on) AND WILL PREVENT THE MID SECTION FROM PROPERLY DRAINING. this could result in cracking the mid section if you live where it gets below freezing. Use the original size grommet, as shown in the middle of the photo for your 1975 model. The kit contains all three style grommets for all years.

Many here erroniousely, and confusingly call the mid section/exhaust housing a "Leg" but I have yet to see an outboard walk on water, anyway, the Canucks are persistant with arcane and odd terminology, so be prepared to "iterpolate" many responses you will get here on I-Boats.

Support I-Boats, they carry all the parts you will need for your engine.

I strongly suggest you get a copy of the service manual, and stay away from the later OMC "catch-all" manuals that cover all models and years, they are not specific enough. You can buy an Evinrude, or Johnson version, years 1974-76 are virtually identical. Lots of them on e-Bay.

Another tip: Leave the original condensors alone, they are made in USA, and the new replacements are made in the Orient and are prone to failure in the short term. If you can locate some new old stock Mallory condensors, made in USA , they are good. The points tend to last indefinitely because of the low current the magneto primary circuit has; just not enough current to arc the point face significantly unless the condensor goes bad.

 

[jmendoza]

Re: 1975 Johnson 15 hp questions

Found a manual for ya

: http://cgi.ebay.com/ebaymotors/1975...60319028494QQptZMotorsQ5fManualsQ5fLiterature

 

[wylie catter]

Re: 1975 Johnson 15 hp questions

Wow, so much great info. I really appreciate it.

I'm definetly in the right place. I'll be asking more questions as I go along. Yall really know your stuff. Right now I'm waiting on the water pump to come in.

Thanks again.

 

[wylie catter]

Re: 1975 Johnson 15 hp questions

Another question. What is the gas oil ratio supposed to be on this engine. I have been running on 50.1 in the barrel and it is running great. But if that's not right then I'll change.

Oh and the water pump rebuild went smooth. It has a spray kinda stream coming out the back now, and it's running cool.

In all it took cleaning the carb, replacing the fuel lines, new plugs, and new water pump to get it running excellent = $57 in total. Plus another $60 or so for tank and line and fitting. But that didn't have anything to do with the motor itself. I'm hoping to test drive it this weekend. I'm putting it on a 16' LUND wide jon that I use to knock around and bait fish.

I love Evinrude and Johnson motors. You can't beat'em.

 

[OptsyEagle]

Re: 1975 Johnson 15 hp questions

50:1 is correct.

 

[wylie catter]

Re: 1975 Johnson 15 hp questions

50:1 is correct.

Thank you!