Exhaust Headers / 525 Mercury Racing Engines
12-29-2010 | 01:18 PM
#111
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Joined: Dec 2000
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From: Bell Canyon, CA
Correct. The plug is replaced with a fitting and a tube runs to the through hull. The tubes are small enough to not effect the water flow through the exhaust and will always drain the pipes after every run or start up. How many people actually drain their exhaust after every run. This is a low cost insurance that water is never sitting in the headers.
Had it for two seasons now.
Had it for two seasons now.
12-29-2010 | 02:16 PM
#112
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Here is an interesting article on the importance of flushing with fresh water thoroughly.....
http://www.dieselduck.ca/machine/04%.../corrosion.htm
Pulled from the above link.
Some divers meticulously rinse their equipment off with fresh water after diving in salt water, and others don’t. I haven’t seen any problems with my equipment if I forget to rinse it off once in a while. Does this rinsing really do any good?
Yes. The chlorides in salt water cause the stainless steel and aluminum alloys that your equipment is made from to pit or to corrode in crevices where oxygen access is limited (and where, by the way, you can’t see it happen until it’s too late). When you take your equipment out of the water, oxygen can usually get to all of the crevice areas, which stops any crevice corrosion. However, if a crevice is very deep, trapped saltwater might cause corrosion to continue. Corrosion in these deep crevices will be stopped by a fresh water rinse. Because your equipment is made from a lot of different metals, galvanic corrosion can also be a problem as long as the different metals are covered with salt water. The lower conductivity of fresh water reduces the amount of galvanic corrosion that can occur. Finally, the salt deposits that form when seawater evaporates are not only ugly, but also hygroscopic, that is, they absorb moisture from the air. Salt deposits absorb enough moisture for the surface to become wet when the relative humidity exceeds 50-75 percent. Your equipment will start to corrode when it is sitting in the shed and you think it is dry. This is the same reason why cars in the northeast corrode more than they do in the south. Road salts form a layer on the car that causes the car to corrode every time the relative humidity goes over 50 percent, even sitting in the garage. So, rinse your equipment. Take good care of it, your life depends on it. And while you’re at it, take your car to the car wash after you’ve driven it on salty roads and it will last longer too.
http://www.dieselduck.ca/machine/04%.../corrosion.htm
Pulled from the above link.
Some divers meticulously rinse their equipment off with fresh water after diving in salt water, and others don’t. I haven’t seen any problems with my equipment if I forget to rinse it off once in a while. Does this rinsing really do any good?
Yes. The chlorides in salt water cause the stainless steel and aluminum alloys that your equipment is made from to pit or to corrode in crevices where oxygen access is limited (and where, by the way, you can’t see it happen until it’s too late). When you take your equipment out of the water, oxygen can usually get to all of the crevice areas, which stops any crevice corrosion. However, if a crevice is very deep, trapped saltwater might cause corrosion to continue. Corrosion in these deep crevices will be stopped by a fresh water rinse. Because your equipment is made from a lot of different metals, galvanic corrosion can also be a problem as long as the different metals are covered with salt water. The lower conductivity of fresh water reduces the amount of galvanic corrosion that can occur. Finally, the salt deposits that form when seawater evaporates are not only ugly, but also hygroscopic, that is, they absorb moisture from the air. Salt deposits absorb enough moisture for the surface to become wet when the relative humidity exceeds 50-75 percent. Your equipment will start to corrode when it is sitting in the shed and you think it is dry. This is the same reason why cars in the northeast corrode more than they do in the south. Road salts form a layer on the car that causes the car to corrode every time the relative humidity goes over 50 percent, even sitting in the garage. So, rinse your equipment. Take good care of it, your life depends on it. And while you’re at it, take your car to the car wash after you’ve driven it on salty roads and it will last longer too.
12-29-2010 | 02:33 PM
#113
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Joined: Sep 2008
Posts: 1,200
Likes: 1
From: LOTO
Correct. The plug is replaced with a fitting and a tube runs to the through hull. The tubes are small enough to not effect the water flow through the exhaust and will always drain the pipes after every run or start up. How many people actually drain their exhaust after every run. This is a low cost insurance that water is never sitting in the headers.
Had it for two seasons now.
Had it for two seasons now.
12-29-2010 | 03:19 PM
#114
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Joined: Nov 2010
Posts: 20
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Running a header with out or with low water VOLUME is bad news, as it causes excessive expansion and contraction with in the header.....something typically has to give and will crack.
12-29-2010 | 03:35 PM
#115
Platinum Member
Joined: Nov 2002
Posts: 4,288
Likes: 87
From: New Jersey
I have the same volume and pressure coming out the exhaust as I did before the drains were installed and have had NO temperature increase in the exhaust or pipes. I pull the boat after each run or at max. after a weekend and the motors get a thorough fresh water flush.
The picture below shows no significant water coming out the tubes, plenty of water out the tailpipes, and no steam.
The idea of leaving water sitting in the pipes to me makes no sense if you can get it out. Besides the corrosion factor, let's say you do have a weld failure or crack, if there is no water sitting in the tubes, there is no water to drain back into the cylinders.
Most damage occurs from the motors sitting for awhile, the water slowly seeping into a port. Go to start it up and Boom!
The only drawback I have found is you do get little stains from the water dribbling down the transom. Nothing a little Spray-Nine can't fix.
The picture below shows no significant water coming out the tubes, plenty of water out the tailpipes, and no steam.
The idea of leaving water sitting in the pipes to me makes no sense if you can get it out. Besides the corrosion factor, let's say you do have a weld failure or crack, if there is no water sitting in the tubes, there is no water to drain back into the cylinders.
Most damage occurs from the motors sitting for awhile, the water slowly seeping into a port. Go to start it up and Boom!
The only drawback I have found is you do get little stains from the water dribbling down the transom. Nothing a little Spray-Nine can't fix.
Last edited by Tom A.; 12-29-2010 at 03:47 PM.
12-29-2010 | 03:40 PM
#116
Platinum Member
Joined: Apr 2005
Posts: 2,150
Likes: 15
From: Northport N.Y.
Last year i fixed 3 sets of cmi headers for a friend they all leaked in the collector area were the 4 pipes meet. Headers are from 2005 it cost him a engine after it sat all winter. I have a set of stellings on my apache only hade to weld 1 tube so far these are also from 2005.
12-29-2010 | 05:03 PM
#117
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Joined: Jan 2009
Posts: 69
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Correct. The plug is replaced with a fitting and a tube runs to the through hull. The tubes are small enough to not effect the water flow through the exhaust and will always drain the pipes after every run or start up. How many people actually drain their exhaust after every run. This is a low cost insurance that water is never sitting in the headers.
Had it for two seasons now.
Had it for two seasons now.
12-29-2010 | 05:09 PM
#118
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Joined: Jan 2009
Posts: 69
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Last year i fixed 3 sets of cmi headers for a friend they all leaked in the collector area were the 4 pipes meet. Headers are from 2005 it cost him a engine after it sat all winter. I have a set of stellings on my apache only hade to weld 1 tube so far these are also from 2005.
12-29-2010 | 05:14 PM
#119
Platinum Member
Joined: Apr 2005
Posts: 2,150
Likes: 15
From: Northport N.Y.
Tig welded the inside with a very small torch around the star pretty hard to do also back purge the water side of the header with gas.
12-29-2010 | 05:40 PM
#120
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Joined: Jan 2009
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Damn, you're pretty good at TIG welding. I don't know how much room you have to get to the inside with only 4 tubes, I have 5 tubes to deal with, but I don't have a torch small enough to get in there. Where did you get this very small torch you have? Is it a Miller?
