1978 25hp Johnson not pumping water

[Skidooosl]

I have a 1978 25 HP Johnson that is having trouble pumping water. The water pump is new and WAS pumping great until we noticed their was just a small trickle squirting out. The water pump still pumps great. Removed the cover over the head and started the engine and water shot out about 4 feet then removed the thermostat and put the cover back on the head and started it but there was still just a very small amount of water squirting out. When we first took it apart we did notice some weeds around the thermostat. Is there another place weeds could be clogging? We also replaced the hose that connects the side of the block to the water nozzle where it squirts out so I know that hose is not plugged. It is somewhere after the head and before the nozzle. also, quite a bit of water comes out of the exhaust ports.

 

[Goodoleboy]

Re: 1978 25hp Johnson not pumping water

If it were me Id pull the hose that connects to the telltale. If is pumping good water up to their, then it mite just be the small telltale hole is partialy pluged.

 

[Skidooosl]

Re: 1978 25hp Johnson not pumping water

That is what i thought as well, only a small dribble came out when i pulled the hose off.

 

[jwstandiford]

Re: 1978 25hp Johnson not pumping water

I was having a similar problem with my 78' 35hp Rude a couple of weeks ago. If there were weeds aroung the t-stat and you are having the same problem with the t-stat out then you can bet that something got into the block. Try taking the hose off of the telltale and blowing about 100psi through the block backwards with the cover off and t-stat out. You might be suprised at what comes out....I know I was.