My guess would be the drain setup is attached to the water rail where the rear blue plastic drain plug would have resided.

Custom Marine is located in Neenah, WI.

Typically testing is with in a couple of days, based on age most are repairable, salt water applications where the headers are overheated have a less chance of a solid repair.
Cost is $150 area on average per header which includes a light clean up, plus transit.

:coolcowboy:

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.

So the CMI headres sold under the CMI name and not Mercury Racing name did not have the same issues?

I have a set of CMI E-Top's from around 2006 do these have issues? I'm running antifreeze in mine.

No they all do.

So CMI used the same spec. knowing that they were too thin and the not heat treated?

cast aluminum manifolds
 

Has anyone looked into the cast aluminum Keith Eickert long tube manifolds. Reliability should be far better than any welded manifold?

Makes sense not to leave water sitting in there.

What about over the winter? I ran AF w/corrosion protectors through the motor. Should i leave the AF in there? Or drain it?