72 Johnson 4HP - Newbie info sought

[arifleman]

Hi guys. Can someone give me a quick rundown on recommended service when acquiring a motor of unknown origin service? Motor is Johnson 4hp, model 4W72S. Assuming this means its a 1972 model - what does the W and the S stand for?

From other posts here it sounds like replacing impellor is pretty standard. Plugs, maybe points as well? Anything else I should look for?

There was no paperwork with this motor - where is a good spot to pick up owner's manual and a shop service manual and parts?

Thanks for the help!

 

[Vic.S]

Re: 72 Johnson 4HP - Newbie info sought

Yes a 1972 model. W is for weedless drive ... the prop is angled downwards and the gear case has a weed shedding shape. S means nothing AFAIK

Read Awakening a Sleeping outboard

Manuals from iBoats possibly
MarineEngine.com
or Ken Cook
but beware of pirated CDs etc on ebay
Parts lists on line HERE

 

[arifleman]

Re: 72 Johnson 4HP - Newbie info sought

Oh, lots of good info at those links. Thank you.

Also, this motor did not come with a fuel tank. Can I use any after market tank? Any benefit to metal over plastic fuel tank? Looks like this motor uses a fuel bulb primer. Does that have to be a specific Johnson part or will any bulb and fuel hose do? Thanks guys.

 

[dad1959]

Re: 72 Johnson 4HP - Newbie info sought

the s stands for saltwater.

 

[Vic.S]

Re: 72 Johnson 4HP - Newbie info sought

Yes any suitably sized tank. Any fuel line and bulb but 5/16" ID will be adequate. You don't need 3/8"

Be sure to get the correct connector ie for Johnson/Evinrude. Some others look the same but don't fit.

Plastic tanks don't leave rusty marks, don't affect the compass but distort alarmingly if they get warm when the vent is closed (I cover mine when its in the sun and the vent is closed.) but I am sure they are sufficiently robust to withstand the pressure build up.

Plastic tanks are not recommended for long term storage of gasoline. In fact with ethanol fuels long term storage is not advisable anyway!

BTW not convinced that the S in the model number means "saltwater"
the 1973 model is 4W73C , '74 model is 4W74R ... what do the C and the R mean if S is saltwater ?

 

[Rick.]

Re: 72 Johnson 4HP - Newbie info sought

Great little motors. I would recommend you check compression before spending any money. If it proves to be good then it's well worth the cost of replacing ignition parts and leg oil and purchasing manuals. Your parts manual is online at this link. Your fuel mix is 50/1. These little guys usually came with a 3 gallon tank. I would recommend plastic over metal. Don't get a big tank as they run all day on very little gas. About a liter an hour of run time. Best of luck. Rick.
http://epc.brp.com/Index.aspx?lang=E&s1=5b66a60b-2f85-4796-8408-f3f5dea52bb1