johnson serial tag washed off?

[matt167]

I just bought an at least '85 Johnson 20hp. I noticed the serial tag is blank. Not mechanically scraped but washed/ faded away. Is there any other way to check model number? I'd like to 25hp convert it if it can be done cheap enough. It has the 100:1 ratio decal if that makes a difference

 

[Grub54891]

There should be a welch plug on the motor with the serial number stamped into it. Usually in the area near or on the head.

 

[racerone]

Remove that 100:1 sticker and mix at 50:1.-----Post pictures of cowling if original.

 

[jimmbo]

The 100:1 places it between 1985 - 88, by 89 they had dropped the 100:1 and switched back to 50:1

 

[matt167]

As far as I know this is original. I'll check the welch plug. I know to run it at 50:1

 

[racerone]

Cowl is from an 86 to 90 model.-----Will look at one laying outside tomorrow.

 

[matt167]

I just got back from running some fogging oil through it. Did not run it very long and I know it was under 50:1 mix. About 3/4 gallon of gas and I put enough oil in it for 1 gallon at 50:1. I noticed no water pumping but I had ears on it and good flow through them. So I basically ran it less than 1 min. Enough to get the fogging oil in it and that's it.

It pumped water out the tell tale perfectly at the guys house and he ran it on ears. I got water out of the prop and slightly out of the top cutouts but no tell tale. Does this need to warm up for the tell tale to work? I was planning on getting a full water pump kit and a new thermostat anyway. It will have those things before it hits the water as well as some new paint and probably some newer model decals

 

[racerone]

Telltale should show seconds after start up.----Does not need to warm up.

 

[matt167]

That's what I thought. I'm pretty sure I might have gotten some grease in the tell tale from carrying it. it seemed to have a drop of water on it. water was coming out of the prop with exhaust. I just did not see any out of the exhaust cutouts. Either way it didn't run long enough to hurt anything and I'm going to put a pump kit in it anyway

 

[Grub54891]

Sometimes the tell tail gets plugged up from mud daubers take a small wire, or zip tie and poke it in there to clean it out. Or remove the hose and clean it out

 

[matt167]

The tell tale worked at the guys house a couple days ago. But not yesterday. I might have gotten some grease in it from carrying it since there is some grease on the bottom.

And do you pump the key for the primer or hold it while turning? I pumped it and it fired up in very little time

 

[matt167]

Can anyone confirm this is the correct pump kit? https://www.iboats.com/shop/sierra-18-3382-water-pump-repair-kit-with-housing.html

 

[racerone]

Your cowling decals are for the 87 / 88 model years.----That is obviously the correct pump kit.

 

[matt167]

Thanks, and I see that I can narrow down the year by the carburator. 1987 20/25hp has the same carb, but 1988 lists 2 separate carbs. So find the casting number and google it. I hope it's a '87 so I can 25hp convert it with an intake