'69 Mercury 650 cooling problem

[PuckHog]

I have a 69 Merc 650 outboard which I replaced the impeller on, yet I'm not getting any water out of the 'tell-tale' pipe. There is pressure in the form of air coming out (slight). I've only run the motor at low rpm. When using the cups, water is definitely pumping out of the water return holes. As it stands, I'm afraid to run the motor very long. As you might have guessed, this is my first outboard.

 

[joblo33]

Re: '69 Mercury 650 cooling problem

Hi, and welcome to the forum.<br />The first step is to spray compressed air into the pisser hole while the engine is running (but dont run it too long without cooling) Wait a few senonds to see if the water flows after that. If not repeat a couple times and if it still isn't coming out report back.

 

[kaytree]

Re: '69 Mercury 650 cooling problem

i have also experienced this problem.<br />was pumping water up to the engine block but wasn't coming out the tell tale pipe. I believe there is another hole at the bottom of the engine block that also allows water to disperse a small amount of water that goes into the leg. After removing the lower unit i put a hose pipe into the copper pipe and water was flooding back down the leg from the bottom of the block. After many hours ( and i mean many) i deiceded to remove the sside engine plate that exposes the waterways and used an air pipe to blow the waterways clear (don't use water as it will go into the piston chamnbers)I couldn't see anything that was blocking but put it all back together and it was ok and pumped water perfectly.<br />good luck

 

[PuckHog]

Re: '69 Mercury 650 cooling problem

That's interesting- There is water running down the front of the lower unit coming out from just under the block. I have the carburettors and fuel pumps off right now for a well deserved cleaning, so before everything is back together I'll try blowing the lines out. There is a brass 1/4" MIP plug on the top of the motor. Is that where I can connect a pressure guage and test my water pressure? Thanks to both for your help.

 

[PuckHog]

Re: '69 Mercury 650 cooling problem

Well, as it turns out, it was my fault. The new impeller works great, I just didn't have the copper supply pipe properly seated in the powerhead. A good lesson for anyone else about to embark upon their first impeller repair. Strangely, the Mercury shop manual doesn't point out the now obvious importance of seating that pipe.