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Hi Ken,

In general, the pencil zincs on heat exchangers are located on the bottom of the cylinder. I've attached a link to a photo of a Mercruiser 7.4 that has a yellow exchanger on it - - the zinc is seen on the lower left. Click the link below:

http://bpi.ebasicpower.com/mm5/merchant.mvc?Screen=PROD&Store_Code=eBasicPower&Product_Code=SANMC-323&Category_Code=MER8H-IB

Hope this helps,

Captain Craig Bliss

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Hi Ken

As Craig suggests the zinc seems to be located on the left bottom side of the heat exchanger as you face the engine from the front (belt) end.

Remember to turn off your seacock before you remove it. Have the new one ready and a bucket to catch the water that drains out when you remove the old one. On my engine I have this on a 60 day maintenance cycle, it's well worth keeping a close eye on the zinc to figure out how often you need to change it.

Best regards,

Captain Ian Fagg