1975 9.9 johnson sea horse

[sgwin]

The motor overheated and quit it tries to start but will not run. I did a compresson test top cyl was 65 bottom was 50 I pulled the rope three times to get this reading,

 

[bktheking]

Re: 1975 9.9 johnson sea horse

Headgasket is probably blown and head could be warped. Did you figure out why it overheated?

 

[sgwin]

Re: 1975 9.9 johnson sea horse

No have not found over heating problem yet. I do have spark and the plugs are wet when I pulled them. Fuel pump does pump but very short pulse and
no pressure

 

[bktheking]

Re: 1975 9.9 johnson sea horse

You will need to solve it or you will wind up with the same issue. Water pump, thermostat stuck, blockage somewhere in the system- these are common, if it's a salt water motor even more likely a blockage.

 

[cst756]

Re: 1975 9.9 johnson sea horse

You will need to solve it or you will wind up with the same issue. Water pump, thermostat stuck, blockage somewhere in the system- these are common, if it's a salt water motor even more likely a blockage.

Sorry to hijack, but where would the blockage be. All of a sudden my 75 9.9. started overheating on muffs (smelled the paint). Checked thermostat (there was not one), put one in and changed the water pump. I did shoot some water up the metal tube from the pump to where the thermostat is and get water. The motor gets hot (real hot) in about 15 or 20 seconds. Any help would be great.

 

[sutor623]

Re: 1975 9.9 johnson sea horse

Hey bud, I have seen blockages at a stuck shut thermostat, and gunk in the water jackets around the cylinders. You can run a water hose up the supply line(with an adapter) and see if the water comes out of the exhaust. It sounds like you need to pull the cylinder head.

 

[sutor623]

Re: 1975 9.9 johnson sea horse

One other thing that you MUST be careful about, is if it is a saltwater motor, the cylinder head bolts may be rusted/siezed. I broke one off and almost had to trash the whole powerhead because of it, luckily a drill press and helicoil later and I saved the motor. If you can, let some PB blaster sit on the bolts for a few days, then if you cant get an compressor air gun to each bolt, pull the powerhead so that you can access the bolts with it. You are much more likely to snap a bolt off by using a wrench to remove the cylinder head. Do not force the bolts loose, if they wont come loose pull the powerhead. TRUST ME you dont want to learn the hard way like I did.......

 

[cst756]

Re: 1975 9.9 johnson sea horse

thanks, ill start pulling it down today.