Very weird problem with 20hp johnso... White Smoke!

Hi, I have a 1994 20hp johnson motor. I started, for the first time after decarb, the motor (it was sitting in my garage for 5years). The motor started from the first pull! Everything is fine except the annoying white smoke (there's was a lot of white smoke). I kept the motor running at half throttle for 45mns but the white smoke was still there when the motor is at very low rpm. The compression if fine. What could be the problem? I now that I did put a litle bit more oil (maybe a 45.1 mixture) and I know that I should have got a blue smoke (but it's white!... water!).

Cheers

Re: Very weird problem with 20hp johnso... White Smoke!

Are you running it on a boat in the water? If not, do so. Run the daylights out of it to burn all that crud out of the exhaust (the de-carb crud). And don't be worrying about the smoke color. Two-stroke outboards are supposed to smoke anyway.

Re: Very weird problem with 20hp johnso... White Smoke!

Yes, it was in the water. There's was a excessive amount of white smoke!!! Edit: Do you think that it is because of the very humid weather

Re: Very weird problem with 20hp johnso... White Smoke!

I dunno, they all smoke down here in the humid swamps.

Re: Very weird problem with 20hp johnso... White Smoke!

When you say smoke, is it white smoke? Is it a lot?
Thanks for your help!

Re: Very weird problem with 20hp johnso... White Smoke!

Aren't most Jonhsons 50/1? How many times did you do the decard thing? I just did mine with the Seafoam decarb method three times and it smoked out the marina, but runs pretty clean. If it's doing it more at low RPM
make sure air/fuel mixture is set right. My 94 8HP called for three turns out. Went 3 1/2 before it really cleared up. But, went out fishing and after a while engine would lose RPM's and start to smoke. After pulling off the cover and sitting there watching saw that the choke pivot bracket due to vib's would start to move slightly opening the choke. If I held it in closed position RPM's would start to come up and smoke virtually stopped. Don't know if your's is doing same but worth checking out. Fix was to put in another washer behind bellcrank screw to tighten down its movement. Now stays at constant RPM with minimal smoke.

Re: Very weird problem with 20hp johnso... White Smoke!

gdombroski said:

Aren't most Jonhsons 50/1? How many times did you do the decard thing? I just did mine with the Seafoam decarb method three times and it smoked out the marina, but runs pretty clean. If it's doing it more at low RPM
make sure air/fuel mixture is set right. My 94 8HP called for three turns out. Went 3 1/2 before it really cleared up. But, went out fishing and after a while engine would lose RPM's and start to smoke. After pulling off the cover and sitting there watching saw that the choke pivot bracket due to vib's would start to move slightly opening the choke. If I held it in closed position RPM's would start to come up and smoke virtually stopped. Don't know if your's is doing same but worth checking out. Fix was to put in another washer behind bellcrank screw to tighten down its movement. Now stays at constant RPM with minimal smoke.

Click to expand...

Yeap, it`s a 50/1. I did the decarb thing once (this year) because the motor was setting in the garage. My motor is doing the same thing, at high rpm, there`s no smoke. Then, when I lower the rpm (around the idle speed), white smoke starts to come out for about 5minutes than stops. When I give the motor some gas and reduce it again, white smoke appears than disappear. However, when I hold it in closed position, the RPM don't varies (which I think is good).
Another thing, it`s normal to have water coming out of the exhaust right?

Thanks

Re: Very weird problem with 20hp johnso... White Smoke!

I don't know....
but I do believe that the white smoke is steam!

I've got the same motor (yr & hp) with a similar concern, moreso this season.

Here's what I'm thinking:

1) Carb is too lean causing an overheating issue (This would also cause a lack of "normal" blue smoke) Too lean means no lube!
2) Motor is overheating (failing water pump, thermostat or clogged cooling passages)
3) Head gasket is leaking causing water to enter combustion chamber
4) Exhaust gases are vaporizing moisture thus producing vapor. This is more pronounced due to cool air temps at the water's surface when the vapor condenses immediately into steam.

The first three are cause for concern, the later is just normal...I guess. I seem to notice it most after WOT...then idle.

I decided to change out my water pump to rule out one possibility and also because it is due. I'll post the results after I get the pump replaced.

Mas

Re: Very weird problem with 20hp johnso... White Smoke!

Thanks for everything, I will take my motor to a garage to see what is the problem. I will give an update next week!

Cheers

Re: Very weird problem with 20hp johnso... White Smoke!

The head gasket need to be replaced