What year is this 15hp Johnson and any new owner advice?

[kidafa]

Hi All,

Last week I purchased a small dinghy for myself and farther to do a bit of fishing out of over the summer here in Australia. 11ft Savage with a 15hp Johnson short shaft.

Im trying to work out what year it is so I can try and find some information on it. Ive looked around for model numbers or a serial but havn't had much luck.

The current plugs in it are Champion QL77JC4, are these correct?

The old owner was mixing it at 25:1, is this correct? Seems a bit rich to me.

What maintenance should I be doing before we start using it?

At the moment it starts on the hose and purrs away very happily. Im yet to take it out in the water but hopefully will later this week.


Thanks in advance,


Chris

 

[samo_ott]

Re: What year is this 15hp Johnson and any new owner advice?

That must be a fast boat! It should be mixed at 50:1. And there should be a model # on the exhaust housing. Post it to get the year.

And welcome to the forum!

 

[kidafa]

Re: What year is this 15hp Johnson and any new owner advice?

That must be a fast boat! It should be mixed at 50:1. And there should be a model # on the exhaust housing. Post it to get the year

Thats what I want to hear! Should I slowly ween it back to 50:1 or just do it?

Sorry but Im an outboard noob, exhaust housing.... where is that is that down the the bottom near the prop as the prop works as the exhaust does it not?

Any maintenance/pre use check over tips?


Cheers,

Chris

 

[kidafa]

Re: What year is this 15hp Johnson and any new owner advice?

So under where this picture was taken here are a few different numbers I could get

190135 NP 21 JQ1

and

J1323404

 

[samo_ott]

Re: What year is this 15hp Johnson and any new owner advice?

Just go straight to 50:1. And check your spark plugs, they may be gummed up a tad from the extra oil. Here is a pic of my older 9.9 data plate near the pin that changes the angle of the engine.

For starters most folks would change the water pump impeller on new engines to them. I'm lazy and usually leave it if it works so it's up to you. Read the top secret file at the top of this forum. There's lotsa good stuff up there. Personally I would change the lower unit oil.

 

[kidafa]

Re: What year is this 15hp Johnson and any new owner advice?

Interesting thats where I thought it was meant to be as I have the slight rise in the body of the engine but no plate on it or any sign of a plate ever being on it...

Yes the plugs are rather oily but the last time it was run it was on the hose idling for a few minutes so its not really an accurate reflection, will do a plug chop up the river some time soon with a new set of plugs.

Old owner gave me the pump and a bottle of gearcase oil too

 

[raczekp1]

Re: What year is this 15hp Johnson and any new owner advice?

hi read articles writen by LeeRoy Wisner,point 14 OB to 23 OB
http://www.sschapterpsa.com/ramblings/Ramblings.html

 

[Aratsman]

Re: What year is this 15hp Johnson and any new owner advice?

Check a round aluminum plug on top of the motor for model and serial #. Should be stern side of motor on top.

 

[ChrisAG]

Re: What year is this 15hp Johnson and any new owner advice?

The old owner was mixing it at 25:1, is this correct? Seems a bit rich to me.

Two different members on this board (forget their names) who seem to be experts on these engines claim that if you regularly operate at full throttle, i.e. over 6000 rpm, you should run richer than 50:1 (regular TCW at 25:1). Failing that, use a synthetic blend like Evinrude XD50 at 40:1.

Reason: the 15 was the highest-reving of all outboards OMC produced, in stock form rated at up to 7000 rpm for some years (6500 for other years). At over 6000 rpm the need for good lubrication increases exponentially.

The previous owner might have done you a real favour by running it at 25:1 - if nothing else, the cylinder bores & pistons are probably in like-new condition (provided it wasn't carboned up, etc., but using an oil like XD50 will reduce or eliminate the formation of carbon).

 

[kidafa]

Re: What year is this 15hp Johnson and any new owner advice?

Check a round aluminum plug on top of the motor for model and serial #. Should be stern side of motor on top.

Any chances of throwing up a picture of where im looking for cos Im not having much luck....


Thanks for the help so far again guys!


Are the current plugs in it the correct ones?

 

[Aratsman]

Re: What year is this 15hp Johnson and any new owner advice?

Look at yellow arrow in posted photo. Photo complimentes of http://www.sschapterpsa.com/ramblings/OMC/OMC%20info.htm

That website is the ultimate 9.9/15 OMC info site. Lots of good info. Do check it out.

My guess is it's a late 80's early 90's.

 

[Aratsman]

Re: What year is this 15hp Johnson and any new owner advice?

Was just taking a closer look at your photo. The model # and serial should be on this tag, marked with red arrow. Looks like it has been painted. I would look closer at this area. Model # should be J15RENA or something like that.

 

[kidafa]

Re: What year is this 15hp Johnson and any new owner advice?

No silver plate where mentioned and nothing on that plate either....

So far all Im aware of its a '91 or newer as it has this shape tiller with kill switch in this position and not on the end like the older models.

What spark plugs should be in it?

 

[samo_ott]

Re: What year is this 15hp Johnson and any new owner advice?

Two different members on this board (forget their names) who seem to be experts on these engines claim that if you regularly operate at full throttle, i.e. over 6000 rpm, you should run richer than 50:1 (regular TCW at 25:1). Failing that, use a synthetic blend like Evinrude XD50 at 40:1.

Reason: the 15 was the highest-reving of all outboards OMC produced, in stock form rated at up to 7000 rpm for some years (6500 for other years). At over 6000 rpm the need for good lubrication increases exponentially.

The previous owner might have done you a real favour by running it at 25:1 - if nothing else, the cylinder bores & pistons are probably in like-new condition (provided it wasn't carboned up, etc., but using an oil like XD50 will reduce or eliminate the formation of carbon).

But don't forget in the mid/late 80's OMC said you could mix them at 100:1 but then later changed it back to 50:1. I mix my '85 J15hp at 50:1. On the flip side, it doesn't hurt much to have a tad extra oil in there. It will foul the plugs more, that's it.

 

[samo_ott]

Re: What year is this 15hp Johnson and any new owner advice?

And from '77-'92 this was the Champion plug recommended for the 9.9 and 15hp:

QL77JC4 (or L78V Surface Gap)

 

[kidafa]

Re: What year is this 15hp Johnson and any new owner advice?

Picked up a fresh set of plugs yesterday and some valvoline 2 stroke outboard tcw-3 oil.

Will fit the plugs, change the gear oil and mix up a fresh batch of two bangga ready for the weekend!

EXCITED MUCH?!?!

 

[Aratsman]

Re: What year is this 15hp Johnson and any new owner advice?

Here's another pic of the aluminum plug I was refering to. I did happen to see that it may not be there on post-79 models though. But it is worth a try. You can see the model and serial number stamped into it.

 

[jrs_diesel]

Re: What year is this 15hp Johnson and any new owner advice?

Here's another pic of the aluminum plug I was refering to. I did happen to see that it may not be there on post-79 models though. But it is worth a try. You can see the model and serial number stamped into it.

My 9.9 (1986) Johnson, has both model and serial on the casting plug. Transom clamps have an ID tag too.