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496 HO Question - What are these and how should they be adjusted?

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496 HO Question - What are these and how should they be adjusted?

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Old 09-27-2016, 12:00 PM
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Default 496 HO Question - What are these and how should they be adjusted?

Valves are located under exhaust manifolds on both sides.
With both closed motor codes low water pressure.
With both open motor overheats to 200 degrees
No issues with heat or pressure before having heads worked on.
Nobody seems to know how they were before being removed and reinstalled.
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Old 09-28-2016, 12:24 AM
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Just to help verify the clarity, Is that two photos merged into almost one photo of the port and starboard side exhaust?

What exhaust system (brand) do you believe to have installed as that don't appear stock Mercruiser 496 MPI. What year?

Do you happen to have a clear overall photo of the exhaust?
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Old 09-28-2016, 09:53 AM
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Looks like Dana marine exhaust. I would call them and inquire.
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Old 09-28-2016, 11:17 AM
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those are Dana exhaust manifolds The same poster asked in another thread - I can open the pics as they are very small ---- my best answers are - possible customer install for draining and or flushing purposes or for winterization draining. 100 % not a stock app nor install from Mercruiser.

Other guess could be to make sure after engine shut down that heat soaked cooling water does not drain back down in the cool fuel area causing fuel to boil away - Vapor lock issues / no restart.
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Old 09-28-2016, 09:02 PM
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If they are Dana's, the valves are closed unless you are draining the water from the engine via the air drains.
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Old 09-28-2016, 09:06 PM
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http://www.marineindustrieswest.com/...96_Install.pdf

Last page of the instructions, in bold letters, it points out the valves are to be closed when running.
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Old 09-28-2016, 09:19 PM
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Originally Posted by donzi matt View Post
http://www.marineindustrieswest.com/...96_Install.pdf

Last page of the instructions, in bold letters, it points out the valves are to be closed when running.
But they arent hooked up conventionally. Usually they are plumbed as a 90 so when they are open they drain. But they have them plumbed as a tee. Unless the blue hose goes to the bilge I dont understand why they are set up like that. Follow the blue lines. Where do they go?

FWIW the little black handle is at 90 degrees on mine. I see no reason why they would or should be straight - that is open. They should be closed.

Also, is water coming out the tails?
Seems like you have a plumbing issue.
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Old 09-28-2016, 10:27 PM
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They are Dana manifolds
Mercury guys here say closed.
Mechanics say they were open when I brought it in.
Both open or closed does not work.
If I open starboard side and close port side it runs at 170 with good pressure.
Maybe over thinking this but I would like to know this is where it should be adjusted.
They do not drain into bilge. They are attached to pick up and exhaust.
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Old 09-28-2016, 10:31 PM
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Water flows out both sides equally.
I did post this in general forum with no results.
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Old 09-28-2016, 10:34 PM
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Motor is 2006
Adrenaline installed motor. Don't know who did manifolds.
Must be someone who has seen this before.
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