1965 18 hp Johnson cooling problem

[Canoe2]

Finally managed to upgrade from my 12 foot to a 14 with a 1965 Johnson 18 on it, but while the previous owner was showing me it run, it stopped exhausting water. I assumed it was because the impeller was toast, but now that i have it apart the impeller looks sound, the key is in the shaft so it should be spinning and pumping. The only thing i noticed wrong was that the grommet on the copper tube is rotten and needs replacement. Is there any way to test if the cooling system is blocked that doesn't involve me removing the head? Thanks much.

 

[interalian]

You can make a hose adapter and use your garden hose to pump water up the tube. Use low/medium pressure.

 

[HighTrim]

You can take off the t stat cover, and shoot water up the copper line, is it making it that far? Intake area free from debris? Vent hole open in housing? If the impeller stays curled, toss it.

 

[Canoe2]

Thanks for the advice, sounds like Friday evening is starting to plan itself. I will see what i find out and report back, thanks.

 

[Canoe2]

Well, used the hose adapter from my sons water balloon, and the water made it out the exhaust. Hopefully blew out whatever was in the way. Thanks a bunch, too bad it is a little too late to fire it up or I could have a full report.

 

[oldboat1]

will want to replace that bad grommet, though -- could still be an issue. (Maybe you are in process of doing that.)

 

[Canoe2]

After I used the hose to push water through, it did exhaust, but didn't seem like quite enough and was still heating up. I removed the thermostat and works great. So it appears I need a new grommet, new o ring on the drive shaft and a new thermostat. Not bad for a fifty year old motor. Thanks for the help.

 

[tomhath]

The head gasket is cheap and easy to replace if the head bolts aren't seized. It's very possible that the water passages in the head are blocked with sand, lime, or salt deposits.

 

[Canoe2]

I am considering doing the head gasket as well, but I might hold off and see how we do with the new grommet and thermostat. With the thermostat out it seems to push quite bit so I think the passages should be clear.

 

[cals4200]

There is a guy on youtube that shows how to make a pee tube right off the cover, Looks pretty easy and lots easier to see than off exhaust. I believe it was off a Evinrude but they should be the same.