What part is leaking water on Mercruiser 350 Mag MPI 5.7 L

nickjb

Recruit
Joined
Jul 2, 2023
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2
We have a 2012 265 Crownline with a Mercruiser 350 Mag MPI 5.7 L engine. One year ago we had the risers and manifolds replaced. At the start of this summer I noticed water trickling from a component below the alternator. When I start the boat it begins to spray from what looks like a corroded bolt. Wide shot attached, with a closer picture below the alternator. What is this part and is the bolt (or whatever the piece is that is spraying the water) replaceable? Can you help me understand what the piece is?

Thanks
Nick
Lavallette, NJ
 

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nickjb

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Joined
Jul 2, 2023
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That's the cool fuel module
Its a drain plug (item 7) which is used to drain system for winterization. Merc does not sell plug seperately. I would remove it and see if you can find something like to replace with.

https://www.mercruiserparts.com/bam/subassembly/31757/15045/60
You rock! It was corroded over but when I cleaned it I could see the blue plastic leftover from the plug. Had to drill it out and the got a replacement. All good now. Thank you for the quick response!
 

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pursuit2460

Petty Officer 2nd Class
Joined
Aug 24, 2004
Messages
189
I bought aftermarket plugs from Amazon. They work in a pinch but I don’t care for the way they fit. Hardin marine make a SS that’s identical to the OEM. They work perfect. Or buy the OEM, Mercury does sell them separate.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,570
1/2-13 bolt 1/2" long and an O-ring

Can use a 1/2-13 x 3/4 with a few washers under the head and the O-ring in a pinch
 

drewm3i

Petty Officer 1st Class
Joined
Dec 31, 1969
Messages
288
These plugs are such a pain in the butt...they're basically single or double use.
 
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