1975 70 hp dropping speed

[adpadbro]

Hello, I run my boat for 20-30 mins fine and then it just bogs down to about 5mph at full throttle. I changed the water pump because I saw that it wasn't spitting water out of the exhaust port, and now that it is changed it still doesn't spit the water out the exhaust port. I think it is over heating but don't know what I should do next?

 

[fireman57]

Re: 1975 70 hp dropping speed

Take the exhaust plates off the side of the engine and make sure the passages are cleaned out. Make sure you install new gaskets. You can also pullt the thermostat and make sure it is working correctly while you have plate that holds the tstat housing off make sure all the water passages are clear. Again make sure you replace the gasket with a new on. While you are in there just put a new one in. Take a hose with a small nozzle on it and make sure that water comes out all the passages. you may need to run a wire through them to clean out any gunk or obstruction. On easy way you can tell if you are overheating is when it slows down you should be able to hold your fingers on the top of the head for a kind of long count of five. Is your overheat alarm hooked up? It is the tan wire coming from the tstat housing.