Johnson 1966 9.5 Thermostat Issues

Ok, we bought this motor about 2 months ago, everything "working", took it into the shop, to get it checked out and tuned up, and after they adjusted the points and carb or whatnot, they found out that one of the cylinders wasnt firing, and for some reason after they fixed this, the water pump blew up... well i replaced the impeller and still no water flow.

i have seen youtube videos of this motor run, and i am sure that i got the impeller installed correctly

anyways, the next thing that i thought it could be was the thermostat, so after a little searching, i found out where it was and i went about removing the cover. the cover doesnt look like it has been removed... ever.

well i broke the edges of the thermostat cover (i pryed from the inside edges, not the screw holes).

so this is about where im at. i looked all over iboats store for the cap (which i still havent been able to remove) and i need the correct seals and springs and whatnot.

the part number 18-3674 doesnt look like it has the cap, and what i need, i could be wrong

keep in mind that i am a newbie to this type of stuff, im good with my hands, i build computers and such, but im not up to speed on the vocabulary and parts this motor requires.

thanks for all the help
Jgweb2000

Re: Johnson 1966 9.5 Thermostat Issues

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Re: Johnson 1966 9.5 Thermostat Issues

The part number that you list 18-3674 is an aftermarket Sierra Kit for a V6 Crossflow engine.

You need a gasket, a rubber seal, and a thermostat. That will not come as a kit.

The gasket is #309580
The seal is #310058
The thermostat is # 5005440 and is 143 dgrees

The Mercury thermostat is just as good at half the price.MM-75692
These you should get from your local dealer.

The metal cap # 309581 is probably not available locally but a salvage yard or dealer in vintage parts like sea-way .com in Seattle will have them.

If the bolts are out, use a mallet and driver to turn the cap a little at a time in each direction, then lift a little and turn a little, and so on until it comes out. If someone put sealer on the gasket, you may have to use a razor blade to break the seal loose. When you put it back together, use a new gasket and no sealer; there is not enough water pressure to need sealer there.

Re: Johnson 1966 9.5 Thermostat Issues

The primary source of water in the 9.5 is the small screened opening just above the propeller. It needs to be very clean, especially if you are trying to run the motor in neutral in a bucket.

When you are in forward gear, the propeller pushes water into the screen, so the flow is greatly improved. The water in a bucket needs to be above the water pump at a minimum, and it is better if it is all the way up to the mid section. Let the water have a chance to fill the water pump, then start the engine.

If you don't have flow then, you could have a water tube blocked, you could have the water tube improperly seated in the rubber grommet on the pump, you could have the water tube pulled down from the adapter at the top, or your cooling circuit could be blocked.

You could also have the pin loose in the impeller.

Re: Johnson 1966 9.5 Thermostat Issues

thanks for the quick replys, i will be getting those parts soon, as for the water pump, i saw a tutorial on google video that showed how they are installed (7.5 johnson) and mine was very similar in layout.

i got the fins on the impeller bent the right way, and that little key pin that fits in the groove is in there too.

jgweb2000

Re: Johnson 1966 9.5 Thermostat Issues

ok, we failed at getting that thermostat cap out, so i think we may have to replace the whole piston cover or whatnot, the part that the the spark plugs go into... oh well, we got alot of that cap out, but the metal has seem to have bonded to itself.

any suggestions?

web

Re: Johnson 1966 9.5 Thermostat Issues

Call the salvage yard and tell them you need a good used cylinder head with the thermostat cover in place, plus a new head gasket. Here is a list. remove the spaces before the ".com":




BTW, I am sure everyone would be interested in the range of prices if you would not mind sharing that information.

Re: Johnson 1966 9.5 Thermostat Issues

I may have one kicking around someplace. Send me a PM if your interested and I'll see what I can find.