525EFI CMI Port Header Hot
03-05-2013, 09:05 PM
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525EFI CMI Port Header Hot
Hello, I have a 2005 29 Fountain with the stock Mercury Racing 525EFI engine and CMI headers. Boat has approx 200 hours. First 75 hours in salt water, remaining hours all fresh water. I recently started the boat to warm it. After about ten minutes of running at idle I noticed the port header was very hot to touch, but the starboard header was cool to the touch. Anyone else experience this? Is this normal or something I should be concerned about? If it’s a problem, any ideas what the fix might be? Thanks in advance.
03-05-2013, 10:26 PM
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I had same issue on a 502 efi with closed cooling system. I noticed the port side exhaust had poor water flow, are experiencing this also? I believe 525's are closed cooling too. I Pulled the end caps off the heat exchanger and found sea weed inside. Cleaned it out and it was fine.
03-07-2013, 10:12 AM
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Header may be leaking
If you have excess oil temp also, after the thermostat opens you got a crack or pin hole in the cmi header. I have had this issue twice...find the pin holes and weld them up. CMI told me to cap it off pressurize to 65 lbs submerge in water and wha-la leak showed right up. $20 to weld up or $5,000 for new ones....
