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Drained Manifold Condition?


SeattleScott's Avatar
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Join Date: Oct 2006
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11-04-06, 10:57 AM   #1  
Drained Manifold Condition?

Hello Fellow Boaters,

I recently drained the manifolds. The drained water from the port side was slightly yellow (seawater/rust) and the plug had some heavy rust scale built up on the inside. The starboard manifold had a slightly green tinged water with a cloudy substance in suspension. The cloudy stuff settled quickly to the bottom of the jug. Do you think the cloudy stuff could be hose deterioration? The green tinge indicative of an antifreeze leak? I have a 95' volvo-penta 5.7L engine with a duoprop sterndrive. Thank you for your input. SeattleScott

 
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thezster's Avatar
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Join Date: Aug 2005
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11-04-06, 11:58 AM   #2  
Is this a closed system?? I'm assuming it is if you put antifreeze in the cooling system - though they are extremely rare in pleasure boats.... plus the fact you mention seawater in the manifold, which is indicative of an open system....

 
SeattleScott's Avatar
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11-05-06, 11:57 AM   #3  
I have a tubular radiator in front of the engine just above the seawater pump. It has an overflow reservoir with green antifreeze. The seawater pump is also connect via hose to one end of it. Is this called a half system with both antifreeze and seawater flowing through the radiator and manifolds? BoatMech recently told me that I shouldn't be too concerned about the manifold drain water color due to metals leaching out during standing time. If I don't know the age of the manifolds/risers should I consider removing the riser for inspection? Thanks from Seattle Scott

 
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11-05-06, 01:08 PM   #4  
Okay... the seawater cools the radiator as well as the exhaust manifolds.... so you'll find seawater in the exhaust manifolds - and freshwater/antifreeze in the engine block. I wouldn't worry about the color of the exhaust manifold water - it's seawater after all - and various things can cause various colors/sediments.

Inspecting the manifolds/risers is almost impossible as all the deterioration happens "inside" where you can't see much. However - if you spend a lot of time in saltwater - you probably should take them apart and see what you can see. You'll get an idea of the inner condition by the port conditions. Typically, with average use, an exhaust manifold lasts about 7 - 10 years in a salty environment - some more, some less... I've got 1800 hours on my current boat - with only freshwater use - and the manifolds/risers are still in excellent condition.

 
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