Well Guys:

I am going to jump into the fray here and let you know what I believe is pretty close to the real story on Mercury Racing Spec CMI sporttube header systems built between 2001 and 2006 on the Merc Racing HP525 and 600sci engines and the Merc Racing HP500efi (e-top equipped stainless headers produced between 2000 and 2002.
From what I have been told and gleened to find out . Merc Racing specified to CMI what material (stainless spec) and what after weld heat treat procedures CMI was to use after the header was welded. (COST CONTOL) very good bean counter definition for make it cost less to us the manufacturer user! The cracking that shows up on most HP500efi, HP525efi and 600sci engines during this period stems from the brinelling of the weld area from welding which basically makes the welds and the surrounding stainless material more brittle and prone to cracking under stress, heat and vibration. The method of welding, the actual welding rod and stainless tube used and the use of or non-use of heat treating after the welding will affect the how the possibility of cracking is controlled and how prevelent it will be.
There is another issue that also amplified this cracking in certain hulls and boats and that was the use of staggered engine setups where the longer tailpipes and larger extended weights and their flexing caused by widely spaced supports and length issues would flex the header to greater extremes and also cause cracking of the welds and tubes at welds. This has happened on a lot of Fountain built boats and some others from some other builders.
Mercury like any big corporation has management performance incentive job sustaining and pay packages that would be and would have been seriously affected for management if they openly addmitted they had thru their specifications created a large and expensive warranty and damage issue. So what do most managers and corporations do in this type of situation. they go MUM, make it a no talk issue, patch the bleeding wounds wherever they can and hope that time and changes will make the problem disappear with the minimum of financial loss back to those who made the BONEHEAD decision to take the risk of an inferior product. With time when it actually fails will hopefully transfer to the buyer as much as possible thru warranty time lapse and careful "Damage Control"!

I am sure they have now changed the specs and have CMI hopefully building a less prone to failure product, but my suggestion to those who have the problem out of any chance for warranty repair or re-imbursement, replace the headers with CMI's GEN-X new replacement header at about $6-$7K per set and don't take the risk of trying to correct the old Merc Racing headers that fall in this group cuase you ain't gonna fix the problem permanantly and you put the expensive repaired engine at risk all over again!
It is my belief that the new headers CMI builds for all the Merc Racing Engines, their own CMI offerings for both Sporttube, E-Top and Big Tube sets are not manaufactured under this specification and are a much more reliable as possible for any stainless tubular header can be.

Also don't kid yourself, even though the Stainless Marine manifold systems are excellent products, they are not going to supply as much power and torque on NA efi or carbed engines as a good set of equal length long tube headers because they can not scavange and breathe as well as well designed tubular headers or manifolds.
When you get to the blower motors the Stainless Marine HI-Torque big tube tuned risers manifold headers can make as much power as most of the best tubular header sets and I am know there are many offshore racers and users who have seen that both on the dyno and in the boats so equipped.

Bottom line here, if you were or are un-luckey enough to own and run a performance boat equipped with these problem headers and you have no warranty recourse I am sorry to say it looks like you "Up the Creek With No Paddle"
Hopefully the percentage of failures will remain fairly small and you will catch the leaks before they damage or destroy you nice engine package. I am glad we did not build or market these products, they would destroy most medium and small producers in quick order.
Just some more wood for the fire!

Beat Regards,
Ray @ Raylar

+1

The SM setup is thinner externally so when it leaks, it goes out first, so you have a chance to fix it before really damaging anything. My brother had a couple sets of them go bad because he was in 'hot' water at his house... the electricity in it ate through everything, leaving the boat in the water for only an hour or two would leave that white film on all the metals.

Also... word is that Merc wanted Stainless Marine to build their stuff, but @ the prices that Merc wanted SM couldn't build a quality product so they turned them down.

This is a real bummer. I'm considering a '05 boat with a 525. I would be going slightly over what I was wanting to spend as it is. But, the boat is very clean and turn-key. The prospect of having to shell out 5K+ more to replace the headers might be a deal breaker.

Approx what percentage of 525's are having issues?

At how many hours is this issue typically showing up?

Dave,
Same here, looking at a 07 boat with 2x 525's W/ 22 hours?! This boat has full warranty, (Dealer demo) so is it a true statement that if under the 1 year warranty period, I lose a motor to a CMI header leak, that Merc. WILL NOT Cover it under warranty?
This could be a deal breaker for me also........
Dean

+2

In doing my pre-shopping for a purchase next year, I had decided that HP525's would be the preferred engine package over the 496HO's. I figured that if I was going to spend the money the HP525's would not be much more in the grand scheme of things.

Now this thread comes along and I think well, it's back to the 496HO's. Then there's a post or two about 496HO's being problem children too.

WTF? Over?

Maybe I should just go back to Ducati's and BMW and Aprillia motorcycles 'cause you guys are scarring the bejesus outta me.

FWIW though....I'm glad you guys are so candid. Thanks.

Tom

I ended up buying a boat w a 525. It has the "redesigned" version of the headers. I'm just going to be sure to keep an eye on things and hope for the best.

I had a 496HO is my last ride and it was pretty good to me. Around 230 hours with minimal issues.

Hi Tom as RAY of Raylar said in a pr thread there have been a few problems with the 496 but when you look at the big picture % wise no more so than any other engines from merc i cant find the thread that i am on about but Ray explains things much better than me . as for the cmi ex that just sucks regards paul

Dave,
What year is your new boat/525?
Thanks,
Dean

The boat is titled as a 2006, it was commissioned Sept. 2005, so, the motor is an 2005.

Take a look at this thread, I posted a pic that identifies them as the redesigned version.

http://www.offshoreonly.com/forums/g...5-headers.html

Dave,
Thanks for the pics, is this the "Cool Collar" design?
Dean