525 Header Leak
 

I am about to switch my stock CMI headers to Stellings, but I want to be sure I understand the problem with the CMI headers leaking before I order the Stellings. Right now I am not having any problems with the headers and everything is working perfectly, but I am looking at this swap simply as a preventative or precautionary measure.

From what I understand, the problem with the CMI headers is a design flaw and a issue with the thickness of the water jacket that causes them to leak with age. Am I correct in my understanding that the Stellings headers do not have this problem? If I change to the Stellings headers, will I have to worry about this potential problem any longer?

Oh yea, the engines are Merc 525EFIs with 200 hours.

As always, thanks for the help.

It is my understanding that CMI built some of the headers for the Merc 525's to a weak spec. Is it practical for CMI to rework/upgrade these headers in a way that give these headers extended life?

Thanks for the link. It says quite a bit about the CMI headers leaking, but there is only one mention of replacing them with Stellings. Is anybody running the Stellings headers. Will they have the same problem?

Talk to Old School, he has Stellings on his, I think they are 5-6 years old. My buddy went through 6 sets of CMI's and now a set of big tubes on his new (used) boat have a leak (80 hours), he is ordering Stellings.

IMHO, CMI, Stellings etc. are stainless and after some time they will all leak.

The new CMI's are anealed (heat treated) which might help but good luck in whatever you do!

Here is what I've been told: The 525efi heads are "specific" bolt pattern only for the header bolt pattern. Therefore, ONLY the Mercury Racing dealer CMI headers will fit the bolt pattern. CMI can't even sell you a set directly. Stellings I hear won't bolt up. Kind of like Microsoft cornering the market right? Just what I've been told. Don't shoot the messenger.

no problem , i'd go eickert or sm...

thought heads are edelbrock?

I am not sure how they work but I am having drains put in mine so when they sit the water doesn't pool @ the block.