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Curious obout header issues

Old 01-27-2014, 10:56 PM
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Eddie Young alerted me to the Merc bulletin (sterndrive no. 2010-1) specifying modifications to the older CMI headers. Spoke with CMI rep last week and he confirmed this mod. Involves blocking off the lower bypass (distribution tube to tailpipe) and enlarging an upper restricter. Forces more water through the headers. You can buy parts from merc, but CMI rep says you can buy parts much cheaper from ACE hardware and then just drill restrictor to larger size. I have seen the open drains installed on the back of the distribution tube on some older posts. Looks like a good way to keep water from sitting, but would result in less water to the headers, negating the Merc/CMI modification. I pulled my 2004 CMI's last weekend and pressure tested with garden hose. No leaks. I will do the water flow mods. May start draining the blue plugs after use to avoid water sitting in pipes in the event that they do eventually crack.
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Old 01-28-2014, 06:10 AM
  #12  
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For the drain tube they only need to be 1/8" so its not goimg to affect water flow while running.
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Old 01-28-2014, 06:39 AM
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Originally Posted by bajamann
Eddie Young alerted me to the Merc bulletin (sterndrive no. 2010-1) specifying modifications to the older CMI headers. Spoke with CMI rep last week and he confirmed this mod. Involves blocking off the lower bypass (distribution tube to tailpipe) and enlarging an upper restricter. Forces more water through the headers. You can buy parts from merc, but CMI rep says you can buy parts much cheaper from ACE hardware and then just drill restrictor to larger size. I have seen the open drains installed on the back of the distribution tube on some older posts. Looks like a good way to keep water from sitting, but would result in less water to the headers, negating the Merc/CMI modification. I pulled my 2004 CMI's last weekend and pressure tested with garden hose. No leaks. I will do the water flow mods. May start draining the blue plugs after use to avoid water sitting in pipes in the event that they do eventually crack.
Yes, you definitely want to do this service bulletin to get more water to the headers. You don't really need to drill the restrictor bushings; you can just remove them. As far as draining the headers, I installed a draining system on my headers that has a bushing on one side connected to a hose that then connects into a tee on the other side that is connected to a ball valve (see picture). After I flush the motor, I let the headers cool off a bit and then open the ball valve draining both headers in one shot.
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Old 01-28-2014, 09:17 AM
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HyFive- I like that set up. It maintains water pressure to the headers and allows for quick draining. Does this drain straight to the bilge or does it drain through hull? Do you have two or four headers hooked to the ball valve.
Panther- the merc bulletin is calling for increasing the water flow to the headers. Seems like the open drain would decrease pressure slightly rather than increase it.Havent decided how to approach this fix yet, but I would hate to crack a weld.
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Old 01-28-2014, 09:58 AM
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Originally Posted by bajamann
HyFive- I like that set up. It maintains water pressure to the headers and allows for quick draining. Does this drain straight to the bilge or does it drain through hull? Do you have two or four headers hooked to the ball valve.
Panther- the merc bulletin is calling for increasing the water flow to the headers. Seems like the open drain would decrease pressure slightly rather than increase it.Havent decided how to approach this fix yet, but I would hate to crack a weld.
It drains to the bilge. The boat is always out of the water with the drain plugs out by the time I'm opening the valves and its fresh water coming out, so I saw no need for another thru-hull fitting. Two headers hooked up to one valve (ie: one setup per motor). One header has a drain hose that runs to the other side with a tee and the ball valve (like you see in the picture) The setup is as follows:

- on the inboard header: 3/4" to 3/8" NPT reducing bushing (goes into distribution tube) , 3/8" MPT x -06 AN 90* elbow, -06 AN hose end to 3/8" ID marine fuel hose, the hose from this end runs to the tee on the outboard header (see below).

- on the outboard header: this is what you see in the picture... ie: custom made tee with 3/4" run, -06 AN leg, 1/2" run, going into a 1/2" SS ball valve, going into a 1/2" to -08 AN male straight adaptor, -08 hose end into 1/2" ID marine fuel hose run down to lowest part of bilge. The hose from the other header connects to the -06 leg of the tee with a -06 hose end.

Open the valve and whoosh.... takes about 20 seconds to drain both headers..

As for Panther's suggestion, I have seen this approach as well and it's perfectly fine as long you use smaller drain lines like 1/8" MPT; under running conditions, the smaller lines will not bleed off the water pressure enough to matter so this is totally fine but then you do need thru-hull dumps because you don't want to fill your bilge while running. The down side of this setup is that you have to have more holes in the transom and the headers will drain as soon as you shut the engine off and the pressure drops. The upside is you shut the key and don't have to do anything.

Personally, I like the headers to cool off a bit before draining them and would prefer not to have more holes in my boat but I know some real professional engine guys that install it exactly the way Panter described and its fine too.

I got all of my parts for this setup from Teague so if you decide to go this route, talk to Eric there and just tell him you want the same header drain setup as "Neil H. with the 47 Fountain" and he will hook you right up...

Last edited by HyFive578; 01-28-2014 at 10:05 AM.
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Old 01-28-2014, 10:07 AM
  #16  
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The easiest and most trouble free way is to simply run a 1/8" hose from the rear of the header water manifold out to the transom down near the water line. When you shut the engine down it simply drains the header slowly and you don't have to worry about forgetting to drain it.

Installing a 1/8" hose would not affect the volume of water to the header.
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Old 01-28-2014, 10:52 AM
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If you look at the transom of my boat, right next to the trim tabs, you will see the header drains. When the engines are running, you don't even see a drop of water come out from them. As soon as you shut them off, water dribbles out for a couple of minutes and "Ta-Da!" no water left sitting in the headers. You can see the running shot, I am getting plenty of water flow through the headers. I have been running this set up for 5 years.
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Old 01-28-2014, 11:33 AM
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Not gonna re-type all of this. http://www.offshoreonly.com/forums/g...options-3.html

But ALL capsulated, or water jacketed headers WILL leak. YOu hear about the 525's most since 525's sold more than 600's etc. If you look at the data, (and I had attorneys involved with this) the % of failure is about the same no matter what motor you got. Merc. CMI or after market CMI will leak the same. It's planned obsolescence. IF they would make it right. (IE gov, specked headers sold by CMI) there would be no need for "aftermarket" stuff and the warranty limits. Early CMI had no "cool color" both inner and other tube were welded to the flange, better design, but more costly and harder to make. Once CMI sold, (Merc decided not to buy.) their stuff got worse. Now you got the typ. US business mentality. Blame it on the other guy. Merc. blames it on CMI, CMI blames it on Merc, and Corsa or other "captain's call product" so the liability passed on, the boat owner sends the $. CMI has 3 problem issues. Cool color area, collector box, and back wash. Merc. with their reversion issues .. no help Gen X, with the "dropped down collector area to avoid or at least help back was and reversion came after I had long discussions with Merc racing and CMI. and about to take legal action. Gen X' came out. Now the water flow VS pressure. Discussed this with Merc. and CMI to death. Soon CMI. via Livorsy came out with a gizmo to check water flow inline with the headers. CMI was kind.. LMAO they offered me a set at cost for my "input". I bought a set of water flow tester at Mcmaster and Car for about 25% of the cost. CMI could go to heII. Do the things I suggest and you can "extend" your troubles, for a while. My CMI's leaked with in 6 Mo. of being new. CMI "fixed it". a few welds, Merc. put some $ toward a valve job. After doing all to "avoid" leaks and cracks, my headers did not leak for 5 years. I do leak downs and comp test often due to reversion and back wash. They are there, but testing often will help you avoid catastrophic $. I just did a leak down a few weeks ago. I'm good, but I have all the "header fixes" in place. A little trouble some opening my drain valves after flush etc. and wait for a while for a "cool" down period, but it's worth it. The constant drain design, I'm not a believer, but it's convenient for sure.
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Old 01-28-2014, 12:58 PM
  #19  
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Originally Posted by Tom A.
If you look at the transom of my boat, right next to the trim tabs, you will see the header drains. When the engines are running, you don't even see a drop of water come out from them. As soon as you shut them off, water dribbles out for a couple of minutes and "Ta-Da!" no water left sitting in the headers. You can see the running shot, I am getting plenty of water flow through the headers. I have been running this set up for 5 years.
Wallah, it's like magic, right Tom!?! ;-)

John T. from Shore Motorsports recommended that to me sometime back in the late 1990's and he's welded and fixed just about all of em! It's a shame that a lot of guys are now seeing the issues present day with the 525's but this isn't a new issue unfortunately.
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