1979 35 hp JOHNSON WATER TROUBLE

[FISHBONE74]

I have a 1979 35 hp johnson that i have had fo almost 2 years and have not fixed the water pumping problem yet. When i turn the key on and the motor is cranking the water pump works great (steady stream of water) but as soon as it fires up and is running on its own the water instantly stops (just like closed a valve) I have replaced the impeller 3 times cup,gaskets made sure the water tube is inplace cleaned the tale tale hose nothing seems to fix the problem HELP!!!!!! ANY IDEALS

THANKS IN ADVANCE

 

[ezeke]

Re: 1979 35 hp JOHNSON WATER TROUBLE

Do you get a little smoke out of the tell-tale from time to time? You probably have a blown exhaust cover gasket.

 

[FISHBONE74]

Re: 1979 35 hp JOHNSON WATER TROUBLE

Thanks for the suggestion i have actually already replaced all of the gaskets on the motor thinking the same thing this motor is giving me lots of fits

thanks
fishbone74

 

[Woodstock60]

Re: 1979 35 hp JOHNSON WATER TROUBLE

How about thermostat or thermostat housing issues?

 

[Woodstock60]

Re: 1979 35 hp JOHNSON WATER TROUBLE

Also I'm thinking like a spun prop, maybe under a load your impeller is spinning on the driveshaft. How is the keyway?

 

[Rick.]

Re: 1979 35 hp JOHNSON WATER TROUBLE

You say you've replaced the impeller 3 times. Are you absolutely certain you are getting the right impeller. When cranking the engine the speed is low rpm and the pump is working as a displacement pump. Once the engine starts and the motor speed picks up it begins to work as a cetrifugal pump. As the speed increases the vanes bend more making the impeller smaller in diameter. I don't know if this makes any sense and I have no idea at what speed this pumping change over happens but it is the only thing I can think of that changes from cranking to running. Best of luck. Rick.

 

[ezeke]

Re: 1979 35 hp JOHNSON WATER TROUBLE

Check the cylinder head according to following Service Bulletin. [click the thumbnail]

 

[Woodstock60]

Re: 1979 35 hp JOHNSON WATER TROUBLE

Check the cylinder head according to following Service Bulletin. [click the thumbnail]

Wow, where did you find that!

 

[samo_ott]

Re: 1979 35 hp JOHNSON WATER TROUBLE

That's why he's an admiral!

 

[FISHBONE74]

Re: 1979 35 hp JOHNSON WATER TROUBLE

Thanks to all for your help I have been out of town for a while and have not been able to check for replies but now i have some new ideals to try THANKS VERY MUCH to all

Thanks
FishBone74