77 1500 new pump and impeller still overheating

[dhendricks]

Ok so i finally got the water pump sorted out, put the lower unit on and started it up. It took about 45 seconds or water to flow from the **** hole, i stuck my hannd under the stream after about 1 min and it was hot as hell! Shut it down and spinkled water on the heads and it sizzled. Im confused the only other thing i can think of would be the poppet valve but i cant find any real info on it. Also im worried about the condition of this motor since its having so many issues, I havent had a chance to test performance because of the overheat issues. Is it a lost cause?

 

[jimmbo]

There is no poppet valve in that engine. It is a unregulated cooling system. You might have a blockage in the pipe leaving the pump, 45 seconds is a very long time for the block to fill up(pisser needs that to happen before it can pee). Here is a pic of my 1984 115 with water cover removed. Most engines aren't that clean inside

 

[dhendricks]

So pull off the exhaust manifold? what should i be looking for as far as motor
failure?

 

[jimmbo]

Pulling the power head off the midsection and looking for blockages in the cooling passages would be my next project. You would need to do that anyway to do the exhaust manifold cover. Sometimes the inner exhaust plate/separator corrodes and lets exhaust gas into the cooling system, which sometimes results in a spurting discharge from the pisser instead of a solid stream

 

[dhendricks]

That sounds about right. It spit and sputters unless it's getting throttle then it's a steady hot stream. This motor has turned into a pain in the ass lol. Is it worth the trouble in your opinion? Also ca you direct me to the appropriate manual? I got the seloc and it's way to vague for major projects.

 

[jimmbo]

Sent you a PM

 

[dhendricks]

Thank you

 

[Chris1956]

Check the water inlet pipe when you get the powerhead off. Sometimes they get crushed or clogged.

You are installing the white plastic water pipe guide into the top of the waterpump, when installing the gearcase, right?

 

[dhendricks]

yes i am, i think i found the issue there was some debris in the copper water line. Where should i aim the thermometer on the motor and what should it read at idle?

 

[CharlieB]

The exhaust side cover should always be cool to touch.

It is very common for that inner exhaust plate to warp or corrode. If compression is even that motor is well worth taking care of. LOT of guys would fight to have their hands on it.

I am one also.

 

[dhendricks]

It runs decent once i can get it started, the carbs definitely need to be overhauled. The guy who had it before rigged the hell out of it, and its a headache fixing one thing just to find a new issue. I think im finally getting her lined out though..........I hope! So as far as the exhaust can i get some heat resistant gasket sealer and use that? Its surprisingly difficult to find parts in my area. I could always order it offline i guess. Also would an exhaust leak cause overheating?

 

[Texasmark]

yes i am, i think i found the issue there was some debris in the copper water line. Where should i aim the thermometer on the motor and what should it read at idle?

No stat, on idle, muffs........10 degrees over the inlet water temp (swag), measured where Jimmbo's right picture was taken, with the cover on of course. Other shot would be at the exhaust manifold and it would be 10-15 degrees hotter (swag but probably not far off).