460 King Cobra overheating mystery

M

mnfbri

Cadet
Joined
May 16, 2004
Messages
6
Hey Ya'll,<br /><br />I am new to boats but learning fast. I have a 7.5 liter 460 King Cobra which is FWC. At first, the engine was overheating and risers getting extremely warm. That problem solved itself after a bit of running it.<br /><br />Now I have a similar but new problem that none of the boat mechanics can figure out...the risers are getting near red-hot but the engine temp is stable at 145 degrees. I have proved adequate waterflow into the engine, and engine temperature is indeed where its supposed to be, and water is coming out of thermostat housing...<br /><br />The common additional problem i've been having all along is that when trying to flush out the engine with the ear-muffs, it doesn't draw water or discharge through the exhaust port in the prop.<br /><br />What could this be? A variety of problems?<br /><br />Any help or ideas would be GREATLY appreciated!<br /><br />Brian<br />brians@3gwireless.tv
 
H

highaltitude

Petty Officer 3rd Class
Joined
May 16, 2004
Messages
82
Re: 460 King Cobra overheating mystery

check for the propper thermostat housing and see if the exhaust manifolds are original
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,088
Re: 460 King Cobra overheating mystery

Risers Plugged ???<br /><br />Start Disconnecting Hoses,+ See Where you have water,+ Where you Don't...........
 
M

mnfbri

Cadet
Joined
May 16, 2004
Messages
6
Re: 460 King Cobra overheating mystery

After checking all the hoses, water flow, cleaning the thermo-housing, etc, i finally decided to check the risers and i discovered something interesting.e..i had the riser gaskets replaced by suggestion from a mechanic who wound up putting the wrong gaskets on...<br /><br />now, i'm no mechanic, and i don't know much about boats yet, but when i inspected the gaskets i saw that the part of the gasket around the exhaust channel had all but disappeared...i think that it was creating back-pressure on the water channels before the exhaust/water mix point. The intake hose was always real cool, and the manifold hose was cool to start and then got real warm. While I am waiting for new gaskets, i put some sealer around the old one (around the exhaust channel especially) and found that water shot out forcefully through the leak i created and the riser cooled down.<br /><br />Do you think I found the real problem?
 
E

expedition175

Recruit
Joined
May 17, 2004
Messages
3
Re: 460 King Cobra overheating mystery

I have a wellcraft elite whit the same motor and sterndrive. I'm curios to know your spec, RPM, speed, and your prop.. thank you!
 
M

mnfbri

Cadet
Joined
May 16, 2004
Messages
6
Re: 460 King Cobra overheating mystery

hi expedition175<br /><br />i got the boat about 3 months ago and don't know what prop size or pitch i have...but i do know that WOT rpm is somewhere close to 5000, top speed is 52mph, and good cruising rpm seems to be around 3500 rpm...anything above that and it eats fuel and really doesn't go all that much faster. sorry, not a boat expert yet! but there are plenty of people on here who have years of experience and can seemingly answer almost anything!!!
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,088
Re: 460 King Cobra overheating mystery

Do you think I found the real problem?
Click to expand...
No Doubt About It.......................
 
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