Cobra overheating

[sea wolf]

Boat is an '87 powered by a 3.0 Cobra. Took it to the lake today, started right up pulled away from the launch & it immediately started to run hot. I figured a bad impeller, so I pulled it & it looks new. I let the engine cool & restarted it, then pulled the hose that connects to the t-stat housing. Nothing, it's dry as a bone. Well, so much for boating today. Got the boat home & started it off muffs & it's running about 160-170 drgrees. Water is exiting from the exhaust & prop housing, but not from the 2 pee holes on the starboard side of the drive. I didn't look at the impeller again. It was getting late, I was tired so I called it a day. I don't think there's a blockage as the impeller looks new. But why would water be exiting from the exhaust but not the 2 pee holes? And how can this be happening anyway when the t-stat hose was as dry as bone, which means it shouldn't be shipping any water. Correct? Maybe I'm just tired, but I don't get it. Any ideas?

 

[sea wolf]

Re: Cobra 3.0 overheating

Re: Cobra 3.0 overheating

Had to work today, so I just got a chance look at it again. Hooked up the muffs & started it. Pulled the hose to the t-stat housing & it's pumping water like crazy, unlike yesterday. However, I'm still not getting a pee stream from the lower unit, but it is pumping water thru the exhaust. Engine running at 160 at idle. I felt the hose to the engine water pump & it's hot to the touch. The hose to the manifold is cool. Pulled the t-stat & dropped it in boiling water & it opened. It's rated at 160 deg. Anybody know why it would overheat on the lake, but run cool off muffs? I did not open it up when I launched it yesterday, didn't get past idle speed before the gauge pegged. And why would it pump water thru that t-stat hose off muffs, but be dry as a bone when it overheated yesterday? I looked at the impeller again, it looks brand new.