454 OMC Overheating Out of the Blue

[libforlife]

I have a 1993 Four Winns Liberator with a OMG King Cobra 454. I took my boat for hours about a week ago and it ran great. Today, it fired up great, let it warm up then brought it down to an idle. I idled for about 5 minutes out of the canal and I noticed my temp gauge rising. It was around 180 degrees. I turned the engine off and opened the engine hatch to see if I could notice anything. Started the engine back up and started to go back in. It really started overheating, my alarm went off because it was up to 220. So, I turned it off for a few minutes and went a little farther quite a few times so I didn't mess anything up.

What would be my best bet to look at first?

It just seems weird it was great last time and when I bring it out today it is overheating.

Any replies would be greatly appreciated.

 

[Dakota47]

Re: 454 OMC Overheating Out of the Blue

sounds like the thermostat is sticking closed.. probablly due to old rubber impeller pieces stuck in there.. Pull of the housing, Backflush with the hose, install new thermostat with new gasket..

 

[Dakota47]

Re: 454 OMC Overheating Out of the Blue

I would put in a new Impeller too... get the whole kit ..new housing and all..

 

[87 bayliner]

Re: 454 OMC Overheating Out of the Blue

i have very simlar problem cept i have 305 omc. after pulling my thermostat housing i noticed it that the thermostat appears to be pressed in permanently into the housing itself. with no way to remove it short of destroying it.
do i have to buy the entire housing just to replace a thermostat? ) ;


j

 

[HT32BSX115]

Re: 454 OMC Overheating Out of the Blue

COOL Another Liberator!



Well a couple of things are important.

Is it closed cooled?

Did you check the impeller, and did you remove the thermostat and check it in a pan of water?

Also, if it's raw water cooled, how old are your risers/elbows?

If it was ran out of water for even 30 seconds, the raw water pump could be completely without vanes.....and those broken vanes could be crammed somewhere and impeding the flow of water.



Cheers,



Rick

 

[MikDee]

Re: 454 OMC Overheating Out of the Blue

Aside from all the great previous suggestions, I'm guessing you checked the water intake on the drive to make sure you didn't get debri, sand, or a plastic bag stuck in there?

 

[libforlife]

Re: 454 OMC Overheating Out of the Blue

Thanks for all the posts fellas, I appreciate it. It ended up being the impeller. It melted to the housing. I will eventually replace the thermostat also.

 

[Coors]

Re: 454 OMC Overheating Out of the Blue

i have very simlar problem cept i have 305 omc. after pulling my thermostat housing i noticed it that the thermostat appears to be pressed in permanently into the housing itself. with no way to remove it short of destroying it.
do i have to buy the entire housing just to replace a thermostat? ) ;


j

an o-ring is holding it in; the rusty junk on it makes it look like part of the housing.