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Copper water pipe used for

E

elgineddie

Contributing Member
"Hello team,
Looking for some

"Hello team,
Looking for someone who really knows their stuff to tell me what this is (see pix). I have a 1998 5.0L and there is a flexible but stiff copper water pipe plumbed from the top of the intake manifold and goes to the starboard exhaust manifold. It's got a rubbery plastic shield running the length.
My SELOC manual doesn't show anything like this and my local marina just stared at me. There has got to be an expert who can shed light.

http://users.foxvalley.net/~spizzirri/h2o.jpg"
http://users.foxvalley.net/~spizzirri/h2o2.jpg""
 
"I would call Mercruiser on th

"I would call Mercruiser on this one. If it stays cool while running, and I suspect that it does, it would probably be for making sure the air/fuel charge stays cool, also. Cold air expands more than hot air and that yields more power."
 
"Actually, I should have state

"Actually, I should have stated that the tube itself gets and stay hot as sin. The engine runs perfectly within its normal operating temp. In fact, the only reason I'm wondering (aside from it not being mentioned in my manual) is because it pumps seriously hot water directly into my starboard exhaust manifold which makes it almost hot to the touch where the port exhaust manifold is cool to the touch.

-Ed"
 
it doesn't pump hot water

it doesn't pump hot water into the exhaust manifold. it runs hot exhaust gasses to the intake.
 
"Ahhhhhh, exhaust gasses. Now

"Ahhhhhh, exhaust gasses. Now it's clear! Thanks Scott!

OK, so you've cleared that up for me but now I gotta still find out why my starboard exhaust riser is hot while the port riser is cool.

Thanks again!
Ed"
 
That would be exhaust gas reci

That would be exhaust gas recirc for emissions considerations I believe.
Sounds like the water flow to your starboard riser may be restricted somehow. You should maybe pull the hose and check the water outflow at idle against the other side. Do this after she is fully warmed up so the t'stat is open.
Rod
 
"The 5.0L is a GM smallblock.

"The 5.0L is a GM smallblock. that means that the passages for the exhaust recirc should be cast into the block. There would be no reason to add an external pipe. Also, there doesn't appear to be an EGR valve in the line anywhere. Maybe part of an intake manifold preheat system that would send exhaust up through the egr ports and back out to the exhaust system through that hose? I've never seen it on a marine engine, but that doesn't mean it doesn't exist! I'll go with Jim N, may be best to contact mfr.

Dan"
 
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