OMC Cobra water flow

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Bruce Morrison

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Testing a newly purchased Bayliner 5.0/Cobra outdrive with a hose attachment and engine running, I had only a minimal amount of water flowing from the prob. After several minutes the engine did not over heat, in fact the exhost manifolds seemed cool to the touch. All of a sudden, warm water started gushing from around the large zink plate (just below the lower bellows). I removed the zink and found the area beneath full of large flakes of rust, the kind cast iron would make. The questions are.... what is the normal exit point and volume of water expected with a hose attachment and engine running, and am I broken or was it just plugged with the rust flakes and now cleared?
 
Scott Danforth

Scott Danforth

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Re: OMC Cobra water flow

guessing that you have rust coming out of your manifolds and risers.

are you boating in salt water? if so, then its probably time to pull the manifolds and risers, inspect, and probably replace.
 
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Bruce Morrison

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Re: OMC Cobra water flow

Do not know the history of boat usage, and you are probably correct about needing to replace the manifolds etc.... but should there be cooling water exiting from around the zink?
 
Don S

Don S

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Re: OMC Cobra water flow

There are two idle relief ports (about 1" dia) cast into the transom shield. Quite normal for water and exhaust to come out of them and not the drive at low rpm.
 
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Bruce Morrison

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Re: OMC Cobra water flow

Thanks to all answering... I will assume I have problems with internal rust, but will also ***-u-me that the water flow is ok now that I have removed all of the rust flakes. Will try it in the water tomorrow and keep a close eye on the temp. I watched several you-tube flicks of hose tests and they all showed water coming out around the bellows just like mine.
 
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Bruce Morrison

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Re: OMC Cobra water flow

Had a good outing on the lake today. The boat ran fine, heated up to 165 170 and no higher regardless of speed. I have a leaking valve cover and have found several wires with crumbling insulation, but all in all I'm pleased.
 
Scott Danforth

Scott Danforth

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Re: OMC Cobra water flow

I would still pull the manifold and risers apart and inspect. if the boat has been in salt water (most likely) the rust flakes you found are from either the riser or manifolds. and if the corrosion is severe enough they leak water into your motor and hydrolock it.
 
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