Mercruiser 260 overheating please help

J

Jhayes780

Petty Officer 2nd Class
Joined
Aug 15, 2022
Messages
150
OK so I got this boat. I took it out on the bay and it was running perfectly fine at low rpm. I got out of the harbor and went 3/4 throttle, and the temperature went from low green to red immediately and started smoking from the engine. I went in the engine compartment and could see the hoses going to the thermostat appeared to be jerking like it was trying to suck on something turned it off let it cool down and turned it back on and it ran fine again at low rpm, but I didn’t want to risk sending it into higher RPMs again. What could’ve caused this issue? What should I do from here? I’m deploying at the end of next month and I’m trying to get as much time on the water as possible. Lol so any help is greatly appreciated.
 
Scott06

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,728
Jhayes780 said:
OK so I got this boat. I took it out on the bay and it was running perfectly fine at low rpm. I got out of the harbor and went 3/4 throttle, and the temperature went from low green to red immediately and started smoking from the engine. I went in the engine compartment and could see the hoses going to the thermostat appeared to be jerking like it was trying to suck on something turned it off let it cool down and turned it back on and it ran fine again at low rpm, but I didn’t want to risk sending it into higher RPMs again. What could’ve caused this issue? What should I do from here? I’m deploying at the end of next month and I’m trying to get as much time on the water as possible. Lol so any help is greatly appreciated.
Click to expand...
First place to start is water pump impeller , if an alpha drive will be in the drive need to split haves. If a bravo drive it will be belt driven on the front of engine.

also check exhaust manifolds and risers for plugging and thermostat while you are in there
 
flashback

flashback

Captain
Joined
Jun 28, 2002
Messages
3,987
All we know is that it's a boat with a mercruiser! Your gonna need to be more specific..
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,234
Jhayes780 said:
What could’ve caused this issue? What should I do from here?
Click to expand...
With any new to you used boat. Before you ever think of putting it in the water.

You pull the drive and do all the maintenance the prior owner didn't do for the past 10 years

New raw water pump, change gear oil, inspect u-joints, gimbal bearing and alignment. Replace the bellows.

Change engine oil and filter, change fuel filter, change plugs, wires, cap and rotor

The smoke was your rubber exhaust hoses and rubber flappers burning up because you had no cooling water
 
J

Jhayes780

Petty Officer 2nd Class
Joined
Aug 15, 2022
Messages
150
Scott Danforth said:
With any new to you used boat. Before you ever think of putting it in the water.

You pull the drive and do all the maintenance the prior owner didn't do for the past 10 years

New raw water pump, change gear oil, inspect u-joints, gimbal bearing and alignment. Replace the bellows.

Change engine oil and filter, change fuel filter, change plugs, wires, cap and rotor

The smoke was your rubber exhaust hoses and rubber flappers burning up because you had no cooling water
Click to expand...
I bought it from a boat shop. A guy ended up abandoning it after work was done and they sold it to me. I did the valves. The impeller etc when I got it. I understand what the smoke was but for it to just go back to normal after turning it on and off I don’t know if I should continue driving or where to begin for maintenance
 
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