johnson 50HP VRO water pump problem help

hi guys i am from the UK i need a little bit help with this USA johnson 50HP VRO outboard
the serial #s are {BJ5OBELCEC) (G 0225301)

The main problem has just happened yesterday i have been using the engine regularly without any problems until yesterday when i went to launch the boat for a days fishing me and my friend arrived at the sea we put the boat in the water started the engine i proceeded to go and park the trailer and car when i returned a maximum of 5 mins later i seen that the engine was not pumping water so i panicked and switched off the engine .
(i had noticed on our previous trip fishing that the water did not start pumping until after 2 mins at tickover)
we waited for 45 mins and started the engine again but still no water pumping just a light puff of smoke came from the water outlets.
we switched the engine straight off and returned the boat back to the trailer and returned home .
when i got home i noticed a good long drip of unburned 2-stroke oil running from the back of the prop.
i am mechanicaly minded and have worked on motorcycle and car engines i have gathered that the water pump may be the fault but i cant date the engine or tell if its a short shaft or long and i am finding parts in the uk very slow for delivery
i can only think the parts come from the states i tried to book it in for a service but thiers a six week waiting list i think i could do the job myself but i could do with some advice
many thanks norman

Re: johnson 50HP VRO water pump problem help

Before you do anything, perform a compression check. The engine may have overheated and you now have a head gasket leak which may allow water into the combustion chamber. If compression is ok, you then need to drop the lower unit. Long shaft or short shaft makes no difference. Start by disconnecting the shift lever which is located beneath the lower carb. When that's disconnected, remove the fasteners at the lower unit. Remove the trim tab as there is a bolt under it. With the engine tilted up you should be able to pull the lower unit off. The water pump assembly sits at the top of the unit and the impeller is driven by a key in the drive shaft. You have the option of replacing the impeller only or the entire pump. If it has not been done before, I'd suggest a complete assembly. The drive shaft rotates clockwise so the vanes on the impeller must curve to the left as the pump is assembled. Some will argue that they right themselves if installed incorrectly but why not do it correctly.

Re: johnson 50HP VRO water pump problem help

FYI,model number BJ50belcec is a 1989 model long shaft (20") with electric start.

Re: johnson 50HP VRO water pump problem help

many thanks for the instructions and information .

does anyone know what the compression readings should be for each cylinder its a 2 cylinder model

thanks again norman

Re: johnson 50HP VRO water pump problem help

this is possibly easy for the experts but i am struggling to remove the lower unit to service the water pump
i have followed the instructions but i am not sure if i am disconnecting the linkage correctly as the lower half drops about a quarter inch and thats it i dont want to force it off because it seems locked by something below the carb the linkage access is restricted by the carb and air filter housing .
i have a manual but it covers just about every outboard johnson made upto 89 and the pictures off the shift lever linkage is for a different model
any help would be great
thanks norman