Drain Plugs on Mercruiser 3.0L - Why the plug by the elbow?

Summett

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This may be a dumb question, but what's the purpose of the drain plug on top of manifold by the exhaust elbow?<br /><br />If the water is drained out the two lower side plugs and you winterize by filling thru the hoses by the thermostat, then what's the purpose of that 3rd plug? <br /><br />Just curious!
 

Don S

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Re: Drain Plugs on Mercruiser 3.0L - Why the plug by the elbow?

Some engines have a closed cooling system and the manifold runs in antifreeze not raw water. Then, you have to drain the elbow because it's still raw water cooled. They don't make seperate types of elbows for raw and closed cooling systems.
 

Bondo

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Re: Drain Plugs on Mercruiser 3.0L - Why the plug by the elbow?

You've mentioned 3 different plugs in the Manifold on a 3.0l,................<br /><br />And,........ Not a Single 1 of them is the Drain.............<br /><br />The Drain is on the Bottom, just aft of center,... It's either a 1/8" Pipe thread, or possibly 1/4" Pipe thread,..........<br /><br />Your looking at CorePlugs,+ Ports that Might be used in Different Applications..................... ;)
 

Don S

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Re: Drain Plugs on Mercruiser 3.0L - Why the plug by the elbow?

Bondo, there IS a 1/4" pipe plug near the base of most risers on about all Merc inline engines with the square or rectangular shaped risers. It's for draining when you have a closed cooling system.
 

Bondo

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Re: Drain Plugs on Mercruiser 3.0L - Why the plug by the elbow?

If the water is drained out the two lower side plugs
Not Doubting Your Word at All Don,....... I'd have to walk out to the Shop to Look,........ :D <br /><br />In Summett's post,..... I read the above,.....<br />And, Knowing that there's the 2 coreplugs that are sometimes threaded,+ there's I think, a water port up by the riser/elbow,.......<br />It sounds to Me,.......<br />That Summett, Still Hasn't gotten his fingers Onto the Actual Drain.................. :rolleyes: That's All,.............
 

Summett

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Re: Drain Plugs on Mercruiser 3.0L - Why the plug by the elbow?

I may not have type the queston very well, but I knew where the drain plugs were (both of them). :) Just didn't know what the 3rd (on the top by the exhuast elbow was ever for).<br /><br />Don cleared it up though, and thanks for the concern though Bondo. Happy Thanksgiving!
 
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