Notices

496HO vs 525

Old 05-28-2014, 04:59 PM
  #21  
Forum Regulator
VIP Member
iTrader: (1)
 
Sydwayz's Avatar
 
Join Date: May 2001
Location: Worldwide
Posts: 23,811
Received 1,172 Likes on 511 Posts
Default

Originally Posted by imartin
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.....
Long story short:
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.
Sydwayz is offline  
Old 05-28-2014, 05:01 PM
  #22  
Registered
 
Join Date: Apr 2013
Location: Lagrange ky
Posts: 309
Likes: 0
Received 0 Likes on 0 Posts
Default

They leak water internally and it winds up in the cylinder.
beaver 3 is offline  
Old 05-28-2014, 06:55 PM
  #23  
Gold Member
Gold Member
 
Dave M's Avatar
 
Join Date: Oct 2000
Location: Hollywood, MD, USA
Posts: 5,651
Received 122 Likes on 77 Posts
Default

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.
Dave M is offline  
Old 05-29-2014, 12:19 PM
  #24  
Registered
 
Join Date: Jan 2005
Location: Katy, TX
Posts: 611
Received 15 Likes on 10 Posts
Default

Originally Posted by beaver 3
They leak water internally and it winds up in the cylinder.
yikes! Was that a problem in 2007? Purely freshwater use.
imartin is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.