78' Johnson 70hp (Water pump and water flow question):

[Jayb123]

I was wondering if water is shooting out of the water outlet "tell-tale" does that mean the water pump is working properly in conjunction with the impellar? Or does that mean the impellar is working properly... but the pump -may not- be? Reason I ask is because the water jacket gets pretty hot ... almost to the point you cant keep your hand on it for longer than a few secs.

 

[fireman57]

Re: 78' Johnson 70hp (Water pump and water flow question):

The telltale lets you know that the water pump is working but doesn't tell you if you have a blockage in the water passages. Is one bank hotter than the other? if it is you have a partial blockage in the water jackets on that side. You should be able to hold your finger on the head for a fairly long count of 5. You can also go to Harbor freight and get a temp gun for about 20 bucks on sale.

 

[Jayb123]

Re: 78' Johnson 70hp (Water pump and water flow question):

I wouldnt say one specific area gets hotter than the other. The jacket as a whole seems pretty hot after running for a few minutes. I do know that i have a good stream "tell-tale". I am however using muffs for this info.... and the motor is not in the water. Im in a motor testing phase.... why I ask Thanks.

 

[ADK_Boater]

Re: 78' Johnson 70hp (Water pump and water flow question):

You could test your thermostat if you think your motor is running hot.

Suspend it from wire in a pot of water on high heat. If you have a big mercury thermometer (not one of the cheap ones) put that in the pot too so that you can monitor the temp. If the thermostat opens at the right temp range then it is ok.

 

[Sixmark]

Re: 78' Johnson 70hp (Water pump and water flow question):

Let's simplify things a little bit......the impeller is essentially your water pump, it moves the water inside of the water pump housing.

If you are experiencing overheating problems there are simple things to check, pull the plugs, do they have water on them?

Do a compression test, this is a good way to find a leaking head gasket.

Look for any water that may be leaking from around the base gasket, and water cover plate.

Check the T-stat and the pressure relief valves for proper operation.