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Originally Posted by imartin
(Post 4129006)
Whats the header issue on the 525? At the gasket? Im looking at a pair of 2007's with 96 hours on them......I want to move up from 496HO to 525, but all this reading is making me nervous.....
The main issue is with the Mercury spec'd headers on the 525EFIs. CMI submitted their header for the OEM package. Mercury wanted something different. (read: cheaper) CMI built what Mercury asked for. Mercury 525EFIs are now know for leaky header issues. especially (but NOT exclusively) to boats with staggered engines, as the forward mounted engine allows for more tailpipe & header vibration. The vibrations over time cause the cracks. |
They leak water internally and it winds up in the cylinder.
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I have a 2005 525EFI. I just replaced the CMI's with Stainless Marine at 230 hrs mainly to be proactive.
The shop that did the work pressure tested the CMI's and said they DID NOT leak. Maybe I was lucky? I did the Merc service bulletin that eliminates the bypass hoses between the distribution rail and the tails. Also, I always drained them when not in use. They where run in a mix of fresh and salt. |
Originally Posted by beaver 3
(Post 4129011)
They leak water internally and it winds up in the cylinder.
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