Johnson 4HP 2 stroke

[TSB240]

Hi
Can anyone confirm that my 4hp jonny/ rude gearbox and prop should come away from the power head by just undoing the 2 bolts under neath the cavitation plate. I think the drive shaft splines are stuck.

It was a very long time ago that I last replaced the impeller! It has always pumped good water out of the pee hole.
This is the small lightweight twin that has a simple gear lever on the side. No reverse!
I suspect the drive shaft has probably corroded and become attached to the powerhead.

This motor has lasted a over 12 years and was one of the last ones made. It has been rescued from the drink twice!
I have left it upside down and have squirted some plus gas onto the drive shaft.

Hoping you can help?

 

[Refueler]

I have a large Johnson Outboard Service book covering from 2hp up to the big bas***s !! of yesteryear ... 2strokes ..

But I need the year and model of your O/bd to see if its in my book ...

 

[Tremyporth]

I think you are correct about the there being only two bolts. I had the same problem with one of those engines, sourced from a boat jumble, but in that case it turned out that somebody had assembled it with some sort of sealant on the splines. You could try pushing some wedges between the leg and gearbox- gently, no rushing! You may end up as I did getting the gearbox off, and water pump top broken as the shaft and key pulled out through it. Shaft was still glued to the powerhead, so then I disconnected powerhead from leg and used heat, vice, grips and hammering to free the shaft. Nice light little engines, but some very small waterways in the cooling system, so well worth taking the powerhead off the leg to make sure they are not blocked.

 

[rotrax]

PM me. I have a tatty but excellent runner plus a tidy looking one that is hard to start, plus some ignition spares. Bits for these most excellent engines are getting hard to find.

They need to go and will be very cheap.

 

[TSB240]

Thanks for the info.
A you tube video has confirmed what I thought that the drive shaft should normally come out of the powerhead first and remain in place with the gearbox and water pump.

I suspect it will probably come out of the gearbox more easily as it is in an oil bath.
The video confirmed as you do that the pump will probably get damaged by the impeller drive coming out through the plastic housing .

I will have to be patient and allow the penetŕating oil to do its job.

Thanks to @Refueler but the serial number came unstuck or destroyed sometime ago!

It's a shame the Chinese only copied the single cylinder motors as spares are getting very rare.

Video for info.

 

[TSB240]

PM me. I have a tatty but excellent runner plus a tidy looking one that is hard to start, plus some ignition spares. Bits for these most excellent engines are getting hard to find.

They need to go and will be very cheap.

Thanks I may take you up depending upon what damage I do!

 

[Snowgoose-1]

Best of luck. Would be interesting to know.
I have one . It's a great little engine with excellent power to weight .