Well she's done

[mars bar]

My 1968 Johnson 65 hp overheated again. I've spent as much money as I'm going to spend on it. I changed the impeller,,rebuilt the cards, changed the points, replaced plugs and wires, new fuel pump.. When it starts seconds later it starts to spray a good amount of water. Runs well for a few minutes then goes slower and slower, all this time a considerable amount of steam is coming from the port hole. Living in Canada the water here is just below freezing so I thought this was the norm. When I started this project the compression was 90 psi all 4 cyl. I hate to see what it is now.

 

[Joe Reeves]

Is there a TAN wire protruding from one of the cylinder heads of that 1968 65hp Johnson engine. That would be a overheat sensor. Let us know if it is there.

It's strange that my parts book does not show one for that particular engine, however that could simply be a printing error.

 

[racerone]

It is normal for what appears to be steam to come out of the idle relief port.---It may just be water vapour !-------By all means do another compression test on it.-----Where in Canada ?

 

[mars bar]

Racerone I'm in St.Catharines Ont. I'll check for that TAN wire.

 

[mars bar]

NO TAN wire, looks like there's a spot on top of the 2/4 cyl . Compression test as follows...cyl 1- 87 lbs. 2- 10 lbs 3- 30 lbs. 4- 70 lbs

 

[gm280]

NO TAN wire, looks like there's a spot on top of the 2/4 cyl . Compression test as follows...cyl 1- 87 lbs. 2- 10 lbs 3- 30 lbs. 4- 70 lbs

Either a totally fried engine OR a blown head gasket. I wouldn't throw in the hat yet. It could be some thing really easy to repair and then you have a good engine again... I would suggest you pull the head and look see... Report back to us with some pictures of the pistons, cylinders, and head/head gasket and see what the experts on here suggest then...

 

[F_R]

1968 65hp was an economy motor. You didn't get overheat sensors with them (tan wire). It was doomed anyway because the 55hp looper made it look silly in the performance & economy field. But the 65 certainly was a good tough motor.

 

[mars bar]

Just finished changing the head gaskets and waterjacket also. Ya it is a big gas sucking pig

 

[mars bar]

but what's causing the overheat "new impeller installed also, was spitting good water flow?

 

[boobie]

What's the compression after changing the head gaskets ??

 

[racerone]

What oil are you mixing in the gasoline ?

 

[boobie]

Have you gotten into the thermostat area on it ??

 

[mars bar]

The compression after changing gaskets was an even 90 psi all 4 cyl. I'm using quick silver oil for outboards and such, and I haven't touched the thermostat because it looked like it was opening after a bit of a warm up.Spraying a good amount of water, one thing I did notice is that the impeller I took out was beefier and seemed stronger than the one I put in and it was a replacement part.