Curious obout header issues
 

I've noticed that there has been a lot of complaining about the CMI headers used by Merc for their 525's. I have a couple of questions:

What is the actual problem?

Does the problem also exist with the 575's, 600's and 700's?

Sounds like there can be significant damage caused; how bad can it get?

Is this something that happens with all CMI headers on Merc products or even on the custom engines?

What does Merc do to solve the problems?

There are plenty of other header manufacturers out there; is this a CMI problem of a casting problem with the heads used by Merc? For example, does this happen with Stelling?

Bottom line:
CMI spec'd a header for the 525EFI for the OEM package.
Mercury didn't like it. They wanted something different. (read: cheaper)

CMI made the headers that Mercury wanted, per Mercury's factory specs.
They did not hold up over time, usually just long enough for factory warranty to expire.

CMI got the bad name/reputation; but not their fault.

CMI's 525EFI headers, that you buy directly from them do NOT have this problem. They are of a different design, spec, and quality. (read: better)

Staggered boats are most easily affected, specifically the forward engine which allows more movement of the tailpipes and headers; allowing the welds to crack; and leaks to take place.
HOWEVER, many, many side/side boats have been affected too.

Also I believe for the most part the years when the problematic headers were produced were in the 03-06 range?

you can destroy an engine if water gets in a cylinder and you hydro lock it...

Sydwayz has it pretty much covered.. Inferior metal alloy used on earlier model 525 headers caused cracking in the welds, causing water ingestion into the engine.

Does the problem also exist with the 575's, 600's and 700's?...

>>> It occurs on 525EFI's, 600SCi's and 700 SCi's as they all use the same header.

Sounds like there can be significant damage caused; how bad can it get?

>>> If they leak and not caught, best case scenario is stuck valve, worst case scenario is hydrolock the motor and say goodbye...

Is this something that happens with all CMI headers on Merc products or even on the custom engines?

>>> This really only is relevant to the MERC spec CMI header; CMI headers that are purchased from them directly are not the same spec. Pre-2004 Merc/CMI headers were the worst.. 2004 - 2008 better but still prone to leaks, post 2008, the spec was changed/improved.

What does Merc do to solve the problems?

>>> Not much...

There are plenty of other header manufacturers out there; is this a CMI problem of a casting problem with the heads used by Merc? For example, does this happen with Stelling?

>>> Has nothing to do with the heads; it's the metal that was used. Not a lot of reports of failure with Hardin Marine or Stellings. I was under the impression that Stellings is out of business.

Thank you guys. I'm always amazed with companies who tout their products as the best, put inferior products out for public consumption and ignore the problems that their pizz-poor decisions cause.

If you can switch to stainless marine cast manifolds I would, they make the same power and never leak. All tubed headers will leak at some point, just a design issue.

It's not specifically a CMI thing, its a header thing... All headers will leak, just some take longer than others.

For what it's worth I am running CMI's manufactured in 92.

Yes to all the 525 Merc spec stuff mentioned above.

With all headers, they should be pressure tested regularly to check for leaks.
Also, I have added header drains which help prevent water laying in them and possibly leaking in while sitting.

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.

For the drain tube they only need to be 1/8" so its not goimg to affect water flow while running.

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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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...

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.

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.

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.

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.