1963 18 hp Fastwin Overheating

[restornator]

Here's the story on this motor. I've had it for 2 seasons, last year it ran fine, yet lacked power, barely spit out any water though...

This year, after replacing the impeller, noticed one spark plug was real weak. After new spark plugs, the motor revved up nicely and was noticeable faster..... for about 1 minute...

The motor overheated on the water and locked up. It turned over again but after 10-15 seconds would rev up and die. After inspection, found the diaphram in the fuel pump all busted up, carburator is clean as a whistle. The thermostat looks to be fine, not ceased up or anything. Fuel mixture is 24:1

Once again, there still doesn't seem to be much water being pumped through, and i don't know if this is correct, but with the exaust plate off (shift linkage access) exaust is coming out this access area. While i inspected the thermostat, i poured water into the housing and could hear it drip into the lower unit

 

[F_R]

Re: 1963 18 hp Fastwin Overheating

Here's the story on this motor. I've had it for 2 seasons, last year it ran fine, yet lacked power, barely spit out any water though...

This year, after replacing the impeller, noticed one spark plug was real weak. After new spark plugs, the motor revved up nicely and was noticeable faster..... for about 1 minute...

The motor overheated on the water and locked up. It turned over again but after 10-15 seconds would rev up and die. After inspection, found the diaphram in the fuel pump all busted up, carburator is clean as a whistle. The thermostat looks to be fine, not ceased up or anything. Fuel mixture is 24:1

Once again, there still doesn't seem to be much water being pumped through, and i don't know if this is correct, but with the exaust plate off (shift linkage access) exaust is coming out this access area. While i inspected the thermostat, i poured water into the housing and could hear it drip into the lower unit

I am somewhat confused why you mention all that stuff like carburetor when talking about a motor that is overheating and locking up. Getting proper cooling should be your #1 concern. You may have already done serious damage to it by running it that hot, and it may be beyond economical repair. But if nothing else, the head gasket has to be replaced.

 

[restornator]

Re: 1963 18 hp Fastwin Overheating

i can turn the flywheel by hand, but what other variables besides the water pump and thermostat cool the motor, that's what i don't know. I was already planning on replacing the head gasket because i need to inspect the cylinders for carbon, one hasn't been firing for a season's time

 

[14ftgrumman]

Re: 1963 18 hp Fastwin Overheating

Pull the flywheel and inspect the coils, plug wires and points. Pay special attention to where the plug wires comnnect to the coils. A challenge to get at, but must be done. Replace any cracked or discolored coils. TORQUE the flywheel nut on reassembly to 40 ft/lb.

Drop lower unit and replace waterpump impeller and plate.
Replace the thermostat.
Put motor in a barrell or garbage can with water atleast 1/2 the way up the lower unit. Fire it up and you should get water comming from the exhaust port.

These are tough little engines and will take some abuse, but not much.

 

[kbait]

Re: 1963 18 hp Fastwin Overheating

I agree, but first check compression after replacing head gasket. You must have >50 to feasibly run. And even if it's only 60psi, it may run way good. Do the other repairs afterwards. Why kick a dead horse? And DO NOT run long if it's not spitting water!!!!