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Merc 525 efi head corrosion

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Merc 525 efi head corrosion

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Old 07-15-2019, 02:00 PM
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Default Merc 525 efi head corrosion

Hello,

have a merc racing 525 efi that I had some corrosion get in between the exhaust manifold and the head and caused an exhaust leak which then led to us finding out that salt has been getting in between slowly and ate the head pretty badly. Sooooo now I知 looking to buy a pair of complete heads. I知 kinda trying to save as much money as Possible since I was quoted a little over 15k from my mechanic because he said I need new heads and 2 new manifolds as well.

Can some of you please give me some insight as to what my options are? Do I need to go with merc heads or is there as aftermarket option that I can look for as far as heads that are same as a merc head I have 2 motors but trying to get away with only doing one Not time for me to upgrade both yet

thabks in advance
Anthony
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Old 07-15-2019, 02:09 PM
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The heads are aluminum Edlebrock and your "manifold" should be a stainless CMI header if stock. Pics of the corrosion would be helpful in terms of whether or not it could be repaired.
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Old 07-15-2019, 03:50 PM
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They haven't made that head in a long time, Id try some of the marine builders see if they have a set laying around. it has a proprietary ( none standard BBC ) bold pattern on the exhaust ports.
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Old 07-15-2019, 05:55 PM
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Bam still shows the OEM head as available, 2100+ as an assembly. It does have a specific exhaust header bolt pattern, so an aftermarket head, many available and some better no doubt. will not accommodate your factory CMI sweeper exhaust. There are redrill plates available to make the std chev bolt pattern header fit the OEM heads, perhaps ther are kits to make the Merc Racing / CMI headders fit an aftermarket set of heads.

Might spend a few to look up a real talented machine shop just to have them take a look see, maybe there is a fix to the problem, I have seen guys have some problems fixed on some of the old 500 carb motor manifolds with some success. I live in an area where we have a local machine shop with a very talented owner, he has made me some real nice parts in the past and I just handed him another little project this morning.
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Old 07-15-2019, 06:54 PM
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Originally Posted by Knot 4 Me View Post
The heads are aluminum Edlebrock and your "manifold" should be a stainless CMI header if stock. Pics of the corrosion would be helpful in terms of whether or not it could be repaired.
so your saying that edlebrock makes the exact heads that fit on my motor? I知 pretty sure my headers are cmi. I知 trying to get this fixed as cheap as possible because I知 gonna trade my boat in for a center console with outboards soon

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Old 07-15-2019, 07:19 PM
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Edelbrock made the original heads for Mercury
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Old 07-15-2019, 10:20 PM
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People drill the 525EFI exhaust holes for standard BBC exhaust hole locations. If your heads are not repairable I would see about drilling/tapping holes for the 525EFI exhaust pattern to the Edelbrock heads. If putting these bolt holes on them is possible I would get the Eddy marine hard anodized castings to stave off (longer) the destructive corrosion in future,
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Old 08-01-2019, 07:01 PM
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Originally Posted by SB View Post
People drill the 525EFI exhaust holes for standard BBC exhaust hole locations. If your heads are not repairable I would see about drilling/tapping holes for the 525EFI exhaust pattern to the Edelbrock heads. If putting these bolt holes on them is possible I would get the Eddy marine hard anodized castings to stave off (longer) the destructive corrosion in future,
What is your casting number for your 525 cylinder head?
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Old 08-02-2019, 10:35 AM
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Originally Posted by Anthony0704 View Post

so your saying that edlebrock makes the exact heads that fit on my motor? I知 pretty sure my headers are cmi. I知 trying to get this fixed as cheap as possible because I知 gonna trade my boat in for a center console with outboards soon

hopefully whoever your trading your boat to doesn稚 read this haha
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Old 08-02-2019, 11:36 AM
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Dart makes an aftermarket 525 EFI replacement head. $2700 per pair.

https://www.cpperformance.com/p-1662...-w-valves.aspx
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