OMC cobra 3.0 Overheating

[Jessfly1]

I just bought a 1991 VIP with a 3.0 omc cobra I/O. Had it out on the lake once and it seemed to over heat a little but nothing to bad ( Just over half way on the temp gauge ). I took it out the next weekend and it overheated ( buried the gauge ) to the point of detonation. I did not like to push it but it was sort of an emergency situation. After killing the ignition the motor was still running and i had to choke it out. The guy i just bought it from said he replaced the impeller the beginning of this season. I have been in mechanics almost my whole life but im sort of new to this boat thing. Is there any know issues with these motors overheating? Any guidance would be greatly appreciated. Thanks.

 

[mkast]

Re: OMC cobra 3.0 Overheating

Have you ever started the engine without water to the sterndrive?

 

[Jessfly1]

Re: OMC cobra 3.0 Overheating

No its always had muffs or been in the lake.

 

[sea wolf]

Re: OMC cobra 3.0 Overheating

Have u looked at the impeller? How do u know that the p.o. didn't run it dry? Most overheat issues can be traced to a bad impeller.

 

[Jessfly1]

Re: OMC cobra 3.0 Overheating

Have u looked at the impeller? How do u know that the p.o. didn't run it dry? Most overheat issues can be traced to a bad impeller.

The p.o. said he replace the impeller the start of this season but upon further investigation i discovered the impeller is screwed. Is it a good idea to back flush the cooling sys. if half the fins on the impeller are missing?

 

[Jessfly1]

Re: OMC cobra 3.0 Overheating

Another question, where does the water get exhausted from? I know where the inlets on the stern are but i don't see any indication as to where the used water gets expelled.

 

[sea wolf]

Re: OMC cobra 3.0 Overheating

The p.o. said he replace the impeller the start of this season but upon further investigation i discovered the impeller is screwed. Is it a good idea to back flush the cooling sys. if half the fins on the impeller are missing?

If u don't find the pieces, it will overheat due to a blockage. The pieces may be in the hose from the transom to the t-stat housing.